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1. JOYS+: The link between the ice and gas of complex organic molecules: Comparing JWST and ALMA data of two low-mass protostars.

Author

Chen, Y., Rocha, W. R. M., van Dishoeck, E. F., van Gelder, M. L., Nazari, P., Slavicinska, K., Francis, L., Tabone, B., Ressler, M. E., Klaassen, P. D., Beuther, H., Boogert, A. C. A., Gieser, C., Kavanagh, P. J., Perotti, G., Le Gouellec, V. J. M., Majumdar, L., Güdel, M., and Henning, Th.

Subjects
THERMAL equilibrium, LOW mass stars, STAR formation, SPACE telescopes, INFRARED spectra, PROTOSTARS
Abstract

Context. A rich inventory of complex organic molecules (COMs) has been observed in high abundances in the gas phase toward Class 0 protostars. It has been suggested that these molecules are formed in ices and sublimate in the warm inner envelope close to the protostar. However, only the most abundant COM, methanol (CH3OH), had been firmly detected in ices before the era of the James Webb Space Telescope (JWST). Now, it is possible to detect the interstellar ices of other COMs and constrain their ice column densities quantitatively. Aims. We aim to determine the column densities of several oxygen-bearing COMs (O-COMs) in both gas and ice for two low-mass protostellar sources, NGC 1333 IRAS 2A (hereafter IRAS 2A) and B1-c, as case studies in our JWST Observations of Young proto-Stars (JOYS+) program. By comparing the column density ratios with respect to CH3OH between both phases measured in the same sources, we can probe the evolution of COMs from ice to gas in the early stages of star formation. Methods. The column densities of COMs in gas and ice were derived by fitting the spectra observed by the Atacama Large Millimeter/submillimeter Array (ALMA) and the JWST/Mid-InfraRed Instrument-Medium Resolution Spectroscopy (MIRI-MRS), respectively. The gas-phase emission lines were fit using local thermal equilibrium models, and the ice absorption bands were fit by matching the infrared spectra measured in laboratories. The column density ratios of four O-COMs (CH3CHO, C2H5OH, CH3OCH3, and CH3OCHO) with respect to CH3OH were compared between ice and gas in IRAS 2A and B1-c. Results. We were able to fit the fingerprint range of COM ices between 6.8 and 8.8 μm in the JWST/MIRI-MRS spectra of B1-c using similar components to the ones recently used for NGC 1333 IRAS 2A. We claim detection of CH4, OCN−, HCOO−, HCOOH, CH3CHO, C2H5OH, CH3OCH3, CH3OCHO, and CH3COCH3 in B1-c, and upper limits have been estimated for SO2, CH3COOH, and CH3CN. The total abundance of O-COM ices is constrained to be 15% with respect to H2O ice, 80% of which is dominated by CH3OH. The comparison of O-COM ratios with respect to CH3OH between ice and gas shows two different cases. On the one hand, the column density ratios of CH3OCHO and CH3OCH3 match well between the two phases, which may be attributed to a direct inheritance from ice to gas or strong chemical links with CH3OH. On the other hand, the ice ratios of CH3CHO and C2H5OH with respect to CH3OH are higher than the gas ratios by 1–2 orders of magnitude. This difference can be explained by gas-phase reprocessing following sublimation, or different spatial distributions of COMs in the envelope, which is an observational effect resulting from ALMA and JWST tracing different components in a protostellar system. Conclusions. The firm detection of COM ices other than CH3OH is reported in another well-studied low-mass protostar, B1-c, following the recent detection in NGC 1333 IRAS 2A. The column density ratios of four O-COMs with respect to CH3OH show both similarities and differences between gas and ice. Although the straightforward explanations would be the direct inheritance from ice to gas and the gas-phase reprocessing, respectively, other possibilities such as different spatial distributions of molecules cannot be excluded. [ABSTRACT FROM AUTHOR]

Published
2024
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2. A JWST inventory of protoplanetary disk ices

Author

Sturm, J. A., primary, McClure, M. K., additional, Beck, T. L., additional, Harsono, D., additional, Bergner, J. B., additional, Dartois, E., additional, Boogert, A. C. A., additional, Chiar, J. E., additional, Cordiner, M. A., additional, Drozdovskaya, M. N., additional, Ioppolo, S., additional, Law, C. J., additional, Linnartz, H., additional, Lis, D. C., additional, Melnick, G. J., additional, McGuire, B. A., additional, Noble, J. A., additional, Öberg, K. I., additional, Palumbo, M. E., additional, Pendleton, Y. J., additional, Perotti, G., additional, Pontoppidan, K. M., additional, Qasim, D., additional, Rocha, W. R. M., additional, Terada, H., additional, Urso, R. G., additional, and van Dishoeck, E. F., additional

Published
2023
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6. Ammonia, carbon dioxide, and the non-detection of the 2152 cm−1 CO band

Author

Jiao He, Giulia Perotti, Shahnewaz M. Emtiaz, Francis E. Toriello, Adwin Boogert, Thomas Henning, and Gianfranco Vidali

Subjects
Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

CO is one of the most abundant ice components on interstellar dust grains. When it is mixed with amorphous solid water (ASW) or located on its surface, an absorption band of CO at 2152 cm$^{-1}$ is always present in laboratory measurements. This spectral feature is attributed to the interaction of CO with dangling-OH bonds (dOH) in ASW. However, this band is absent in observational spectra of interstellar ices. This raises the question whether CO forms a relatively pure layer on top of ASW or is in close contact with ASW, but not via dangling bonds. We aim to determine whether the incorporation of NH$_3$ or CO$_2$ into ASW blocks the dOH and therefore reduces the 2152 cm$^{-1}$ band. We performed laboratory experiments to simulate the layered structure of the ice mantle, that is, we grew CO ice on top of 1) pure ASW, 2) NH$_3$:H$_2$O=10:100 mixed ice, and 3) CO$_2$:H$_2$O=20:100 mixed ice. Infrared spectra were measured to quantify the strength of the 2152 cm$^{-1}$ band. In addition, a second set of experiments were performed to determine how the incorporation of NH$_3$ into ASW affects the dOH band. We found that annealing the ice reduces the 2152 cm$^{-1}$ band and that NH$_3$ blocks the dOH on ASW surface and therefore reduces the 2152 cm$^{-1}$ band more effectively than CO$_2$. We suggest that this difference between NH$_3$ and CO$_2$ can be ascribed to the polarity of the guest molecule (NH$_3$ is a polar species, whereas CO$_2$ is apolar). The polarity implies that the formation of an H-bond between the N atom of ammonia and the dOH is a barrier-less reaction. We also determined the pore surface area of the ice mixtures as a function of the annealing temperature, and found that the nondetection of 2152 cm$^{-1}$ band does not necessarily exclude the possibility of a porous ice mantle., Comment: 10 pages, 10 figures

Published
2022
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8. Complex organic molecules in low-mass protostars on Solar System scales

Author

Nazari, P., primary, van Gelder, M. L., additional, van Dishoeck, E. F., additional, Tabone, B., additional, van ’t Hoff, M. L. R., additional, Ligterink, N. F. W., additional, Beuther, H., additional, Boogert, A. C. A., additional, Caratti o Garatti, A., additional, Klaassen, P. D., additional, Linnartz, H., additional, Taquet, V., additional, and Tychoniec, Ł., additional

Published
2021
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9. Complex organic molecules in low-mass protostars on Solar System scales

Author

van Gelder, M. L., primary, Tabone, B., additional, Tychoniec, Ł., additional, van Dishoeck, E. F., additional, Beuther, H., additional, Boogert, A. C. A., additional, Caratti o Garatti, A., additional, Klaassen, P. D., additional, Linnartz, H., additional, Müller, H. S. P., additional, and Taquet, V., additional

Published
2020
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10. Infrared spectra of complex organic molecules in astronomically relevant ice mixtures

Author

M. G. Rachid, D. de Boe, Gleb Fedoseev, A. C. A. Boogert, Harold Linnartz, and N. Brunken

Subjects
LABORATORIES, Astrochemistry, Methods: laboratory: molecular, Infrared, Analytical chemistry, Techniques: spectroscopic, Infrared spectroscopy, Context (language use), Astrophysics, Spectral line, MOLECULES, chemistry.chemical_compound, DEFORMATION, Fourier transform infrared spectroscopy, Physics, ASTROCHEMISTRY, AMMONIA, SPECTRA'S, FOURIER TRANSFORM INFRARED SPECTROSCOPY, Molecular data, Methylamine, COMPLEX ORGANIC MOLECULES, SPECTROSCOPIC [TECHNIQUES], ICE, Astronomy and Astrophysics, MOLECULAR DATA, Methods: laboratory: solid state, ISM: molecules, Amorphous solid, chemistry, Space and Planetary Science, MOLECULES [ISM], REFRACTIVE INDEX, LABORATORY: MOLECULAR [METHODS], LABORATORY: SOLID STATE [METHODS], LABORATORY [METHODS]
Abstract

Context. In the near future, high spatial and spectral infrared (IR) data of star-forming regions obtained by the James Webb Space Telescope may reveal new solid-state features of various species, including more intriguing classes of chemical compounds. The identification of complex organic molecules (COMs) in the upcoming data will only be possible when laboratory IR ice spectra of these species under astronomically relevant conditions are available for comparison. For this purpose, systematic series of laboratory measurements are performed, providing high-resolution IR spectra of COMs. Here, spectra of pure methylamine (CH3NH2) and methylamine-containing ices are discussed. Aims. The work is aimed at characterizing the mid-IR (500–4000 cm−1, 20–2.5 μm) spectra of methylamine in pure and mixed ices to provide accurate spectroscopic data of vibrational bands that are most suited to trace this species in interstellar ices. Methods. Fourier transform infrared spectroscopy is used to record spectra of CH3NH2 in the pure form and mixed with H2O, CH4, and NH3, for temperatures ranging from 15 to 160 K. The IR spectra in combination with HeNe laser (632.8 nm) interference data of pure CH3NH2 ice was used to derive the IR band strengths of methylamine in pure and mixed ices. Results. The refractive index of amorphous methylamine ice at 15 K was determined as being 1.30 ± 0.01. Accurate spectroscopic information and band strength values are systematically presented for a large set of methylamine-containing ices and different temperatures. Selected bands are characterized and their use as methylamine tracers is discussed. The selected bands include the following: the CH3 antisymmetric stretch band at 2881.3 cm−1 (3.471 μm), the CH3 symmetric stretch band at 2791.9 cm−1 (3.582 μm), the CH3 antisymmetric deformation bands, at 1455.0 and 1478.6 cm−1 (6.873 and 6.761 μm), the CH3 symmetric deformation band at 1420.3 cm−1 (7.042 μm), and the CH3 rock at 1159.2 cm−1 (8.621 μm). Using the laboratory data recorded in this work and ground-based spectra of ices toward YSOs (Young Stellar Objects), upper-limits for the methylamine ice abundances are derived. In some of these YSOs, the methylamine abundance is less than 4% relative to H2O.

Published
2021
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14. Stringent upper limit of CH4 on Mars based on SOFIA/EXES observations

Author

Aoki, S., primary, Richter, M.J., additional, DeWitt, C., additional, Boogert, A., additional, Encrenaz, T., additional, Sagawa, H., additional, Nakagawa, H., additional, Vandaele, A. C., additional, Giuranna, M., additional, Greathouse, T. K., additional, Fouchet, T., additional, Geminale, A., additional, Sindoni, G., additional, McKelvey, M., additional, Case, M., additional, and Kasaba, Y., additional

Published
2018
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16. Infrared spectroscopy of HCOOH in interstellar ice analogues

Author

Harold Linnartz, Guido W. Fuchs, Suzanne E. Bisschop, E. F. van Dishoeck, and Adwin Boogert

Subjects
Physics, Interstellar ice, Astrophysics (astro-ph), Ultra-high vacuum, Analytical chemistry, FOS: Physical sciences, Infrared spectroscopy, Astronomy and Astrophysics, Context (language use), Astrophysics, Spectral line, Matrix (chemical analysis), Full width at half maximum, Space and Planetary Science, Low Mass
Abstract

Context: HCOOH is one of the more common species in interstellar ices with abundances of 1-5% with respect to solid H2O. Aims: This study aims at characterizing the HCOOH spectral features in astrophysically relevant ice mixtures in order to interpret astronomical data. Methods: The ices are grown under high vacuum conditions and spectra are recorded in transmission using a Fourier transform infrared spectrometer. Pure HCOOH ices deposited at 15 K and 145 K are studied, as well as binary and tertiary mixtures containing H2O, CO, CO2 and CH3OH. The mixture concentrations are varied from 50:50% to ~10:90% for HCOOH:H2O. Binary mixtures of HCOOH:X and tertiary mixtures of HCOOH:H2O:X with X = CO, CO2, and CH3OH, are studied for concentrations of ~10:90% and ~7:67:26%, respectively. Results: Pure HCOOH ice spectra show broad bands which split around 120 K due to the conversion of a dimer to a chain-structure. Broad single component bands are found for mixtures with H2O. Additional spectral components are present in mixtures with CO, CO2 and CH3OH. The resulting peak position, full width at half maximum and band strength depend strongly on ice structure, temperature, matrix constituents and the HCOOH concentration. Comparison of the solid HCOOH 5.9, 7.2, and 8.1 micron features with astronomical data toward the low mass source HH 46 and high mass source W 33A shows that spectra of binary mixtures do not reproduce the observed ice features. However, our tertiary mixtures especially with CH3OH match the astronomical data very well. Thus interstellar HCOOH is most likely present in tertiary or more complex mixtures with H2O, CH3OH and potentially also CO or CO2, providing constraints on its formation., 11 pages, 10 figures, accepted by A&A

Published
2007
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17. C2D Spitzer-IRS spectra of disks around T Tauri stars

Author

Ruud Visser, J. C. Augereau, Geoffrey A. Blake, Fred Lahuis, Jacqueline E. Kessler-Silacci, Adwin Boogert, E. F. van Dishoeck, Bruno Merín, J. M. Brown, C. P. Dullemond, Neal J. Evans, Klaus Pontoppidan, Vincent Geers, Laboratoire d'Astrophysique de Grenoble (LAOG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
stars : pre-main sequence, 010504 meteorology & atmospheric sciences, INFRARED-EMISSION, Continuum (design consultancy), MU-M, Astrophysics, circumstellar matter, 01 natural sciences, Spectral line, POLYCYCLIC AROMATIC-HYDROCARBONS, ISM : molecules, RADIATIVE-TRANSFER, Spitzer Space Telescope, planetary systems : protoplanetary disks, CIRCUMSTELLAR DISKS, 0103 physical sciences, Radiative transfer, 010303 astronomy & astrophysics, HERBIG AE/BE STARS, 0105 earth and related environmental sciences, Line (formation), Physics, astrochemistry, FORMING REGION, Astronomy and Astrophysics, TRANSIENTLY HEATED PARTICLES, T Tauri star, Wavelength, Stars, 13. Climate action, Space and Planetary Science, MAIN-SEQUENCE STARS, INTERSTELLAR DUST
Abstract

International audience; Aims.We search for Polycyclic Aromatic Hydrocarbon (PAH) features towards young low-mass (T Tauri) stars and compare them with surveys of intermediate mass (Herbig Ae/Be) stars. The presence and strength of the PAH features are interpreted with disk radiative transfer models exploring the PAH feature dependence on the incident UV radiation, PAH abundance and disk parameters. Methods: .Spitzer Space Telescope 5-35 μm spectra of 54 pre-main sequence stars with disks were obtained, consisting of 38 T Tauri, 7 Herbig Ae/Be and 9 stars with unknown spectral type. Results: .Compact PAH emission is detected towards at least 8 sources of which 5 are Herbig Ae/Be stars. The 11.2 μm PAH feature is detected in all of these sources, as is the 6.2 μm PAH feature for the 4 sources for which short wavelength data are available. However, the 7.7 and 8.6 μm features appear strongly in only 1 of these 4 sources. Based on the 11.2 μm feature, PAH emission is observed towards at least 3 T Tauri stars, with 14 tentative detections, resulting in a lower limit to the PAH detection rate of 8%. The lowest mass source with PAH emission in our sample is T Cha with a spectral type G8. All 4 sources in our sample with evidence for dust holes in their inner disk show PAH emission, increasing the feature/continuum ratio. Typical 11.2 μm line intensities are an order of magnitude lower than those observed for the more massive Herbig Ae/Be stars. Measured line fluxes indicate PAH abundances that are factors of 10-100 lower than standard interstellar values. Conversely, PAH features from disks exposed to stars with T_eff≤ 4200 K without enhanced UV are predicted to be below the current detection limit, even for high PAH abundances. Disk modeling shows that the 6.2 and 11.2 μm features are the best PAH tracers for T Tauri stars, whereas the 7.7 and 8.6 μm bands have low feature over continuum ratios due to the strongly rising silicate emission.

Published
2006
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18. Extension of the HCOOH and CO2 solid-state reaction network during the CO freeze-out stage: inclusion of H2CO.

Author

Qasim, D., Lamberts, T., He, J., Chuang, K.-J., Fedoseev, G., Ioppolo, S., Boogert, A. C. A., and Linnartz, H.

Subjects
PHOSPHORS, INFRARED absorption, ICE cores, INFRARED spectroscopy, MASS spectrometry, BRANCHING ratios
Abstract

Context. Formic acid (HCOOH) and carbon dioxide (CO2) are simple species that have been detected in the interstellar medium. The solid-state formation pathways of these species under experimental conditions relevant to prestellar cores are primarily based off of weak infrared transitions of the HOCO complex and usually pertain to the H2O-rich ice phase, and therefore more experimental data are desired. Aims. Here, we present a new and additional solid-state reaction pathway that can form HCOOH and CO2 ice at 10 K "non-energetically" in the laboratory under conditions related to the "heavy" CO freeze-out stage in dense interstellar clouds, i.e., by the hydrogenation of an H2CO:O2 ice mixture. This pathway is used to piece together the HCOOH and CO2 formation routes when H2CO or CO reacts with H and OH radicals. Methods. Temperature programmed desorption – quadrupole mass spectrometry (TPD-QMS) is used to confirm the formation and pathways of newly synthesized ice species as well as to provide information on relative molecular abundances. Reflection absorption infrared spectroscopy (RAIRS) is additionally employed to characterize reaction products and determine relative molecular abundances. Results. We find that for the conditions investigated in conjunction with theoretical results from the literature, H + HOCO and HCO + OH lead to the formation of HCOOH ice in our experiments. Which reaction is more dominant can be determined if the H + HOCO branching ratio is more constrained by computational simulations, as the HCOOH:CO2 abundance ratio is experimentally measured to be around 1.8:1. H + HOCO is more likely than OH + CO (without HOCO formation) to form CO2. Isotope experiments presented here further validate that H + HOCO is the dominant route for HCOOH ice formation in a CO-rich CO:O2 ice mixture that is hydrogenated. These data will help in the search and positive identification of HCOOH ice in prestellar cores. [ABSTRACT FROM AUTHOR]

Published
2019
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19. Stringent upper limit of CH4 on Mars based on SOFIA/EXES observations

Author

Matthew J. Richter, M. Case, Hiromu Nakagawa, C. DeWitt, Adwin Boogert, Giuseppe Sindoni, Thomas K. Greathouse, Marco Giuranna, Yasumasa Kasaba, Hideo Sagawa, Thérèse Encrenaz, Ann Carine Vandaele, Shohei Aoki, M. McKelvey, A. Geminale, Thierry Fouchet, University of California [Davis] (UC Davis), University of California, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Center for Mathematical Sciences, The University of Aizu, National Agriculture and Food Research Organization, Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Istituto Nazionale di Astrofisica (INAF), Southwest Research Institute [San Antonio] (SwRI), Tohoku University [Sendai], Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and National Agriculture and Food Research Organization (NARO)

Subjects
[PHYS]Physics [physics], Martian, Physics, 010504 meteorology & atmospheric sciences, Stratospheric Observatory for Infrared Astronomy, Northern Hemisphere, Astronomy and Astrophysics, Atmosphere of Mars, Mars Exploration Program, Effects of high altitude on humans, 01 natural sciences, Astrobiology, Atmosphere, 13. Climate action, Space and Planetary Science, 0103 physical sciences, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Spectrograph, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

Discovery of CH4 in the Martian atmosphere has led to much discussion since it could be a signature of biological and/or geological activities on Mars. However, the presence of CH4 and its temporal and spatial variations are still under discussion because of the large uncertainties embedded in the previous observations. We performed sensitive measurements of Martian CH4 by using the Echelon-Cross-Echelle Spectrograph (EXES) onboard the Stratospheric Observatory for Infrared Astronomy (SOFIA) on 16 March 2016, which corresponds to summer (Ls = 123.2∘) in the northern hemisphere on Mars. The high altitude of SOFIA (~13.7 km) enables us to significantly reduce the effects of terrestrial atmosphere. Thanks to this, SOFIA/EXES improves our chances of detecting Martian CH4 lines because it reduces the impact of telluric CH4 on Martian CH4, and allows us to use CH4 lines in the 7.5 μm band which has less contamination. However, our results show no unambiguous detection of Martian CH4. The Martian disk was spatially resolved into 3 × 3 areas, and the upper limits on the CH4 volume mixing ratio range from 1 to 9 ppb across the Martian atmosphere, which is significantly less than detections in several other studies. These results emphasize that release of CH4 on Mars is sporadic and/or localized if the process is present.

Published
2018
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20. Bands of solid CO$_\mathsf{2}$ in the 2-3μm spectrum of S 140:IRS1

Author

Pascale Ehrenfreund, W. A. Schutte, A. C. A. Boogert, Aggm Tielens, and Jacqueline V. Keane

Subjects
Physics, Line-of-sight, Space and Planetary Science, Infrared spectroscopy, Particle, Protostar, Astronomy and Astrophysics, Astrophysics, Absorption (chemistry), Spectrum (topology), Spectral line
Abstract

We investigate the 2-3 µm ISO-SWS spectrum of the luminous protostellar object S 140:IRS1. Two narrow absorption features are detected at 2.70 and 2.77 μm, which are well fitted with laboratory spectra of the ν_1 + ν_3 and the 2ν_2 + ν_3 combination modes of solid . The ice in this line of sight must have been subjected to significant heating, in agreement with previously studied CO_2 bands. A combined laboratory fit to all CO2 bands detected toward S 140:IRS1 shows, among others, the need for particle shape calculations for the CO_2 stretch mode. Finally, we discuss the absence of features of isolated H_2O and dangling OH groups in the spectrum of S 140:IRS1.

Published
2001
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21. Herschel observations of EXtra-Ordinary Sources (HEXOS): detecting spiral arm clouds by CH absorption lines

Author

Qin, S. L., Lis, D. C., Phillips, T. G., Bell, T. A., Blake, G. A., Emprechtinger, M., Lord, S. D., Zmuidzinas, J., Boogert, A., Karpov, A., and Kooi, J.

Subjects
Astrophysics::Galaxy Astrophysics
Abstract

We have observed CH absorption lines (J = 3/2, N = 1 ← J = 1/2, N = 1) against the continuum source Sgr B2(M) using the Herschel/HIFI instrument. With the high spectral resolution and wide velocity coverage provided by HIFI, 31 CH absorption features with different radial velocities and line widths are detected and identified. The narrower line width and lower column density clouds show “spiral arm” cloud characteristics, while the absorption component with the broadest line width and highest column density corresponds to the gas from the Sgr B2 envelope. The observations show that each “spiral arm” harbors multiple velocity components, indicating that the clouds are not uniform and that they have internal structure. This line-of-sight through almost the entire Galaxy offers unique possibilities to study the basic chemistry of simple molecules in diffuse clouds, as a variety of different cloud classes are sampled simultaneously. We find that the linear relationship between CH and H_2 column densities found at lower A_V by UV observations does not continue into the range of higher visual extinction. There, the curve flattens, which probably means that CH is depleted in the denser cores of these clouds.

Published
2010

22. Ortho-to-para ratio of interstellar heavy water [Letter]

Author

Vastel, C., Ceccarelli, C., Caux, E., Coutens, A., Cernicharo, J., Bottinelli, S., Demyk, K., Faure, A., Wiesenfeld, L., Scribano, Y., Bacmann, A., Hily-Blant, P., Maret, S., Walters, A., Bergin, E. A., Blake, G. A., Castets, A., Crimier, N., Dominik, C., Encrenaz, P., Gerin, M., Hennebelle, P., Kahane, C., Klotz, A., Melnick, G., Pagani, L., Parise, Berengere, Schilke, P., Wakelam, V., Baudry, A., Bell, T., Benedettini, M., Boogert, A., Cabrit, S., Caselli, P., Codella, C., Comito, C., Falgarone, E., Fuente, A., Goldsmith, P. F., Helmich, F., Henning, T., Herbst, E., Jacq, T., Kama, M., Langer, W., Lefloch, B., Lis, D., Lord, S., Lorenzani, A., Neufeld, D., Nisini, B., Pacheco, S., Pearson, J., Phillips, T., Salez, M., Saraceno, P., Schuster, K., Tielens, X., van der Tak, F., van der Wiel, M. H. D., Viti, S., Wyrowski, F., Yorke, H., Cais, P., Krieg, J. M., Olberg, M., and Ravera, L.

Subjects
QB
Abstract

Context. Despite the low elemental deuterium abundance in the Galaxy, enhanced molecular D/H ratios have been found in the environments of low-mass star-forming regions, and in particular the Class 0 protostar IRAS 16293-2422.\ud Aims. The CHESS (Chemical HErschel Surveys of Star forming regions) key program aims to study the molecular complexity of the interstellar medium. The high sensitivity and spectral resolution of the Herschel/HIFI instrument provide a unique opportunity to observe the fundamental 1- transition of the ortho-D2O molecule, which is inaccessible from the ground, and determine the ortho-to-para D2O ratio.\ud Methods. We detected the fundamental transition of the ortho-D2O molecule at 607.35 GHz towards IRAS 16293-2422. The line is seen in absorption with a line opacity of 0.62 ± 0.11 (1σ). From the previous ground-based observations of the fundamental 1 – 1 transition of para-D2O seen in absorption at 316.80 GHz, we estimate a line opacity of 0.26 ± 0.05 (1σ).\ud Results. We show that the observed absorption is caused by the cold gas in the envelope of the protostar. Using these new observations, we estimate for the first time the ortho-to-para D2O ratio to be lower than 2.6 at a 3σ level of uncertainty, which should be compared with the thermal equilibrium value of 2:1.

Published
2010

23. Herschel/HIFI measurements of the ortho/para ratio in water towards Sagittarius B2(M) and W31C

Author

Lis, D. C., Phillips, T. G., Bell, T. A., Emprechtinger, M., Blake, G. A., Monje, R., Zmuidzinas, J., Lord, S. D., Morris, P., Boogert, A., Karpov, A., and Kooi, J.

Abstract

We present Herschel/HIFI observations of the fundamental rotational transitions of ortho- and para-H_(2)^(16)O and H_(2)^(18)O in absorption towards Sagittarius B2(M) and W31C. The ortho/para ratio in water in the foreground clouds on the line of sight towards these bright continuum sources is generally consistent with the statistical high-temperature ratio of 3, within the observational uncertainties. However, somewhat unexpectedly, we derive a low ortho/para ratio of 2.35 ± 0.35, corresponding to a spin temperature of ~27 K, towards Sagittarius B2(M) at velocities of the expanding molecular ring. Water molecules in this region appear to have formed with, or relaxed to, an ortho/para ratio close to the value corresponding to the local temperature of the gas and dust.

Published
2010

24. Herschel spectral surveys of star-forming regions: Overview of the 555–636 GHz range

Author

Ceccarelli, C., Boogert, A., Lis, D., Bell, T., Blake, G. A., Lord, S., and Phillips, T. G.

Abstract

High resolution line spectra of star-forming regions are mines of information: they provide unique clues to reconstruct the chemical, dynamical, and physical structure of the observed source. We present the first results from the Herschel key project “Chemical HErschel Surveys of Star forming regions”, CHESS. We report and discuss observations towards five CHESS targets, one outflow shock spot and four protostars with luminosities bewteen 20 and 2 × 10^(5) L_☉: L1157-B1, IRAS 16293-2422, OMC2-FIR4, AFGL 2591, and NGC 6334I. The observations were obtained with the heterodyne spectrometer HIFI on board Herschel, with a spectral resolution of 1 MHz. They cover the frequency range 555–636 GHz, a range largely unexplored before the launch of the Herschel satellite. A comparison of the five spectra highlights spectacular differences in the five sources, for example in the density of methanol lines, or the presence/absence of lines from S-bearing molecules or deuterated species. We discuss how these differences can be attributed to the different star-forming mass or evolutionary status.

Published
2010

25. Detection of OH+ and H2O+ towards Orion KL

Author

Maryvonne Gerin, G. A. Blake, J. Stutzki, Shanshan Yu, S. Wang, Paul Hartogh, D. Johnstone, Thomas F. Giesen, Goutam Chattopadhyay, M. Perault, José Cernicharo, Ryszard Szczerba, Rudolf Schieder, Fabien Daniel, S. D. Lord, Jonas Zmuidzinas, Rafael Bachiller, Nathan R. Crockett, Alexandre Karpov, Neal R. Erickson, William B. Latter, John Gill, N. Harada, C. Joblin, P. Zaal, Marie-Lise Dubernet, Erich Schlecht, David A. Neufeld, P. F. Goldsmith, J. A. Murphy, René Liseau, Eric Herbst, C. Comito, Neil Trappe, H. Gupta, E. A. Bergin, A. C. A. Boogert, D. C. Lis, J. R. Goicoechea, Michael Olberg, Jacob Kooi, Jean-Michel Krieg, Frank Maiwald, W. Baechtold, Laurent Pagani, H. W. Yorke, T. A. Bell, F. F. S. van der Tak, Peter Schilke, Martin Emprechtinger, Cecilia Ceccarelli, Volker Ossenkopf, Stephan Schlemmer, Bengt Larsson, Paul B. Rimmer, W. D. Langer, P. J. Encrenaz, R. H. Lin, S.-L. Qin, N. Honingh, J. C. Pearson, Pierrick Martin, M. Salez, S. Cabrit, Emmanuel Caux, Thomas G. Phillips, Karl M. Menten, Sébastien Maret, Rene Plume, Patrick W. Morris, M. C. Diez-Gonzalez, Jesús Martín-Pintado, L. Nordh, Lorene Samoska, R. Güsten, Holger S. P. Müller, Charlotte Vastel, E. Falgarone, Gary J. Melnick, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Ohio State university Departement of Physic, Colombus, Ohio State University [Columbus] (OSU), Ohio State university Departement of Astronomy, Colombus, Ohio State university Departement of Chemistry, Colombus, foreign laboratories (FL), CERN [Genève], Ohio State Univ, Dept Phys, Columbus, OH 43210 USA, Ohio State Univ, Dept Astron & Chem, Columbus, OH 43210 USA, Ohio State University Dept Chemistry, Department of Astronomy [Ann Arbor], University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University-Smithsonian Institution, Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Millimeter-Wave Electronics Laboratory [ETH Zürich] (MWE), Department of Information Technology and Electrical Engineering [Zürich] (D-ITET), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Laboratoire Optimisation de la Conception et Ingénierie de l'Environnement (LOCIE), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Centre d'étude spatiale des rayonnements (CESR), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), CNRS INSU, UMR 5187, F-31028 Toulouse 4, France, UMR 5187 Toulouse, Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Max Planck Institute for Radio Astronomy, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL), Laboratoire de Radioastronomie (LRA), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Cahill Center for Astronomy and Astrophysics, California Institute of Technology (CALTECH), Natl Res Council Canada, Herzberg Inst Astrophys, Victoria, BC V9E 2E7 Canada, Natl Res Council Canada, Herzberg Inst Astrophys, Victoria, Laboratoire de Modélisation Multi-échelles des Combustibles (LM2C), Service d'Etudes de Simulation du Comportement du combustibles (SESC), Département d'Etudes des Combustibles (DEC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Département d'Etudes des Combustibles (DEC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Max-Planck-Institut für Radioastronomie (MPIFR), Infrared Processing and Analysis Center (IPAC), Onsala Space Observatory, Chalmers University of Technology [Göteborg], Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), SRON Netherlands Institute for Space Research (SRON), Department of Physics and Astronomy [Calgary], University of Calgary, I. Physikalisches Institut [Köln], Universität zu Köln = University of Cologne, Laboratoire de Didactique André Revuz (LDAR (EA_4434)), Université d'Artois (UA)-Université Paris Diderot - Paris 7 (UPD7)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12), Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, A.M.Obukhov Institute of Atmospheric Physics (IAP), Russian Academy of Sciences [Moscow] (RAS), Harvard University [Cambridge]-Smithsonian Institution, Univ Toulouse UPS, Ctr Etud Spatiale Rayonnements, F-31062 Toulouse 9, France, Centre Etud Spatiale Rayonnements Toulouse, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), CALTECH, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA, CALTECH, Ctr Infrared Proc & Anal, Pasadena, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Universität zu Köln, Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Université Paris Diderot - Paris 7 (UPD7)-Université d'Artois (UA), Max-Planck-Institut für Sonnensystemforschung (MPS), Department of Physics [Columbus], Department of Astronomy [Columbus], Department chemistry and Biochemistry [Columbus], Department of Physics and Astronomy [Baltimore], Johns Hopkins University (JHU), Smithsonian Institution-Harvard University [Cambridge], Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Observatorio de Yebes, Instituto Geografico Nacional (IGN), Laboratoire de Physique Moleculaire pour l'Atmosphere et l'Astrophysique (LPMAA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich)-Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Ctr Astrobiol CSIC INTA, Lab Astrofis Mol, Madrid 28850, Spain, Ctr Astrobiol CSIC INTA, Lab Astrofis Mol, Madrid, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction de l'Energie Nucléaire (CEA-DEN), Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany, Univ Cologne, Inst Phys 1, and Astronomy

Subjects
[PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], HERSCHEL OBSERVATIONS, Analytical chemistry, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, LINE, Astrophysics, LASER MAGNETIC-RESONANCE, 7. Clean energy, 01 natural sciences, ISM: abundances, outflows, Ion, STAR-FORMATION, REGION, NEBULA, Ionization, 0103 physical sciences, Absorption (logic), 010306 general physics, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, Physics, SPECTROSCOPY, astrochemistry, Astronomy and Astrophysics, INTERSTELLAR H3O+, Astrophysics - Astrophysics of Galaxies, DIFFUSE CLOUDS, molecular processes, [PHYS.ASTR.GA]Physics [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], 13. Climate action, Space and Planetary Science, COMET-KOHOUTEK, Astrophysics of Galaxies (astro-ph.GA), stars: winds, submillimeter: ISM, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], Order of magnitude, line: identification
Abstract

We report observations of the reactive molecular ions OH$^+$, H$_2$O$^+$, and H$_3$O$^+$ towards Orion KL with Herschel/HIFI. All three $N=1-0$ fine-structure transitions of OH$^+$ at 909, 971, and 1033GHz and both fine-structure components of the doublet {\it ortho}-H$_2$O$^+$ $1_{11}-0_{00}$ transition at 1115 and 1139GHz were detected; an upper limit was obtained for H$_3$O$^+$. OH$^+$ and H$_2$O$^+$ are observed purely in absorption, showing a narrow component at the source velocity of 9 kms$^{-1}$, and a broad blueshifted absorption similar to that reported recently for HF and {\it para}-H$_{2}^{18}$O, and attributed to the low velocity outflow of Orion KL. We estimate column densities of OH$^+$ and H$_2$O$^+$ for the 9 km s$^{-1}$ component of $9 \pm 3 \times 10^{12}$cm$^{-2}$ and $7 \pm 2 \times 10^{12}$cm$^{-2}$, and those in the outflow of $1.9 \pm 0.7 \times 10^{13}$cm$^{-2}$ and $1.0 \pm 0.3 \times 10^{13}$cm$^{-2}$. Upper limits of $2.4\times 10^{12}$cm$^{-2}$ and $8.7\times 10^{12}$cm$^{-2}$ were derived for the column densities of {\it ortho} and {\it para}-H$_3$O$^+$ from transitions near 985 and 1657GHz. The column densities of the three ions are up to an order of magnitude lower than those obtained from recent observations of W31C and W49N. The comparatively low column densities may be explained by a higher gas density despite the assumption of a very high ionization rate., 5 pages, 1 figure. Accepted to and to be published in the Herschel HIFI special issue of A\&A Letters

Published
2010
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26. Nitrogen hydrides in the cold envelope of IRAS 16293-2422 [Letter]

Author

Hily-Blant, P., Maret, S., Bacmann, A., Bottinelli, S., Parise, Berengere, Caux, E., Faure, A., Bergin, E. A., Blake, G. A., Castets, A., Ceccarelli, C., Cernicharo, J., Coutens, A., Crimier, N., Demyk, K., Dominik, C., Gerin, M., Hennebelle, P., Henning, T., Kahane, C., Klotz, A., Melnick, G., Pagani, L., Schilke, P., Vastel, C., Wakelam, V., Walters, A., Baudry, A., Bell, T., Benedettini, M., Boogert, A., Cabrit, S., Caselli, P., Codella, C., Comito, C., Encrenaz, P., Falgarone, E., Fuente, A., Goldsmith, P. F., Helmich, F., Herbst, E., Jacq, T., Kama, M., Langer, W., Lefloch, B., Lis, D., Lord, S., Lorenzani, A., Neufeld, D., Nisini, B., Pacheco, S., Phillips, T., Salez, M., Saraceno, P., Schuster, K., Tielens, X., van der Tak, F., van der Wiel, M. H. D., Viti, S., Wyrowski, F., and Yorke, H.

Subjects
QB
Abstract

Nitrogen is the fifth most abundant element in the Universe, yet the gas-phase chemistry of N-bearing species remains poorly understood. Nitrogen hydrides are key molecules of nitrogen chemistry. Their abundance ratios place strong constraints on the production pathways and reaction rates of nitrogen-bearing molecules. We observed the class 0 protostar IRAS 16293-2422 with the heterodyne instrument HIFI, covering most of the frequency range from 0.48 to 1.78 THz at high spectral resolution. The hyperfine structure of the amidogen radical o-NH2 is resolved and seen in absorption against the continuum of the protostar. Several transitions of ammonia from 1.2 to 1.8 THz are also seen in absorption. These lines trace the low-density envelope of the protostar. Column densities and abundances are estimated for each hydride. We find that NH:NH2:NH3 ≈ 5:1:300. Dark clouds chemical models predict steady-state abundances of NH2 and NH3 in reasonable agreement with the present observations, whilst that of NH is underpredicted by more than one order of magnitude, even using updated kinetic rates. Additional modelling of the nitrogen gas-phase chemistry in dark-cloud conditions is necessary before having recourse to heterogen processes.

Published
2010

27. Polarisation observations of VY Canis Majoris H_2O 5_(32)–4_(41) 620.701 GHz maser emission with HIFI

Author

Harwit, M. and Boogert, A. C. A.

Subjects
Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

Context. Water vapour maser emission from evolved oxygen-rich stars remains poorly understood. Additional observations, including polarisation studies and simultaneous observation of different maser transitions may ultimately lead to greater insight. Aims. We have aimed to elucidate the nature and structure of the VY CMa water vapour masers in part by observationally testing a theoretical prediction of the relative strengths of the 620.701 GHz and the 22.235 GHz maser components of ortho H_2O. Methods. In its high-resolution mode (HRS) the Herschel Heterodyne Instrument for the Far Infrared (HIFI) offers a frequency resolution of 0.125 MHz, corresponding to a line-of-sight velocity of 0.06 km s^(-1), which we employed to obtain the strength and linear polarisation of maser spikes in the spectrum of VY CMa at 620.701 GHz. Simultaneous ground based observations of the 22.235 GHz maser with the Max-Planck-Institut für Radioastronomie 100-m telescope at Effelsberg, provided a ratio of 620.701 GHz to 22.235 GHz emission. Results. We report the first astronomical detection to date of H_2O maser emission at 620.701 GHz. In VY CMa both the 620.701 and the 22.235 GHz polarisation are weak. At 620.701 GHz the maser peaks are superposed on what appears to be a broad emission component, jointly ejected from the star. We observed the 620.701 GHz emission at two epochs 21 days apart, both to measure the potential direction of linearly polarised maser components and to obtain a measure of the longevity of these components. Although we do not detect significant polarisation levels in the core of the line, they rise up to approximately 6% in its wings.

Published
2010

28. Herschel/HIFI discovery of interstellar chloronium (H_2Cl^+)

Author

Lis, D. C., Bell, T. A., Phillips, T. G., Blake, G. A., Boogert, A., Emprechtinger, M., Zmuidzinas, J., and Lord, S. D.

Abstract

We report the first detection of chloronium, H_2Cl^+, in the interstellar medium, using the HIFI instrument aboard the Herschel Space Observatory. The 2_(12)−1_(01) lines of ortho-H^(35)_2 Cl^+ and ortho-H^(37)_2 Cl^+ are detected in absorption towards NGC 6334I, and the 1_(11)−0_(00) transition of para-H^(35)_2 Cl^+ is detected in absorption towards NGC 6334I and Sgr B2(S). The H_2Cl^+ column densities are compared to those of the chemically-related species HCl. The derived HCl/H_2Cl^+ column density ratios, ~1–10, are within the range predicted by models of diffuse and dense photon dominated regions (PDRs). However, the observed H_2Cl^+ column densities, in excess of 10^(13) cm^(−2), are significantly higher than the model predictions. Our observations demonstrate the outstanding spectroscopic capabilities of HIFI for detecting new interstellar molecules and providing key constraints for astrochemical models.

Published
2010

29. Herschel/HIFI discovery of interstellar chloronium (H2Cl+) [Letter]

Author

Lis, D. C., Pearson, J. C., Neufeld, D. A., Schilke, P., Mueller, H. S. P., Gupta, H., Bell, T. A., Comito, C., Phillips, T. G., Bergin, E. A., Ceccarelli, C., Goldsmith, P. F., Blake, G. A., Bacmann, A., Baudry, A., Benedettini, M., Benz, A., Black, J., Boogert, A., Bottinelli, S., Cabrit, S., Caselli, P., Castets, A., Caux, E., Cernicharo, J., Codella, C., Coutens, A., Crimier, N., Crockett, N. R., Daniel, F., Demyk, K., Dominic, C., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Fuente, A., Gerin, M., Giesen, T. F., Goicoechea, J. R., Helmich, F., Hennebelle, P., Henning, Th., Herbst, E., Hily-Blant, P., Hjalmarson, A., Hollenbach, D., Jack, T., Joblin, C., Johnstone, D., Kahane, C., Kama, M., Kaufman, M., Klotz, A., Langer, W. D., Larsson, B., Le Bourlot, J., Lefloch, B., Le Petit, F., Li, D., Liseau, R., Lord, S. D., Lorenzani, A., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Murphy, J. A., Nagy, Z., Nisini, B., Ossenkopf, V., Pacheco, S., Pagani, L., Parise, Berengere, Perault, M., Plume, R., Qin, S. -L., Roueff, E., Salez, M., Sandqvist, A., Saraceno, P., Schlemmer, S., Schuster, K., Snell, R., Stutzki, J., Tielens, A., Trappe, N., van der Tak, F. F. S., van der Wiel, M. H. D., van Dishoeck, E., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wang, S., Wyrowski, F., Yorke, H. W., Yu, S., Zmuidzinas, J., Delorme, Y., Desbat, J. -P., Guesten, R., Krieg, J. -M., and Delforge, B.

Subjects
QB
Abstract

We report the first detection of chloronium, H2Cl+, in the interstellar medium, using the HIFI instrument aboard the Herschel Space Observatory. The 212–101 lines of ortho-HCl+ and ortho-HCl+ are detected in absorption towards NGC 6334I, and the 111–000 transition of para-HCl+ is detected in absorption towards NGC 6334I and Sgr B2(S). The H2Cl+ column densities are compared to those of the chemically-related species HCl. The derived HCl/H2Cl+ column density ratios, ~1–10, are within the range predicted by models of diffuse and dense photon dominated regions (PDRs). However, the observed H2Cl+ column densities, in excess of 1013 cm-2, are significantly higher than the model predictions. Our observations demonstrate the outstanding spectroscopic capabilities of HIFI for detecting new interstellar molecules and providing key constraints for astrochemical models.

Published
2010

30. Herschel observations of EXtra-Ordinary Sources (HEXOS): Detection of hydrogen fluoride in absorption towards Orion KL

Author

Phillips, T. G., Lis, D. C., Bell, T. A., Emprechtinger, M., Blake, G. A., Latter, W. D., Lord, S. D., Morris, P., Zmuidzinas, J., Boogert, A., Karpov, A., and Kooi, J.

Abstract

We report a detection of the fundamental rotational transition of hydrogen fluoride in absorption towards Orion KL using Herschel/HIFI. After the removal of contaminating features associated with common molecules (“weeds”), the HF spectrum shows a P-Cygni profile, with weak redshifted emission and strong blue-shifted absorption, associated with the low-velocity molecular outflow. We derive an estimate of 2.9 × 10^(13) cm^(-2) for the HF column density responsible for the broad absorption component. Using our best estimate of the H_2 column density within the low-velocity molecular outflow, we obtain a lower limit of ~1.6 × 10^(-10) for the HF abundance relative to hydrogen nuclei, corresponding to ~0.6% of the solar abundance of fluorine. This value is close to that inferred from previous ISO observations of HF J = 2–1 absorption towards Sgr B2, but is in sharp contrast to the lower limit of 6 × 10^(-9) derived by Neufeld et al. for cold, foreground clouds on the line of sight towards G10.6-0.4.

Published
2010

31. Herschel/HIFI measurements of the ortho/para ratio in water towards Sagittarius B2(M) and W31C

Author

Benjamin Godard, Jonas Zmuidzinas, T. A. Bell, John H. Black, Frank Maiwald, Martin Emprechtinger, Maryvonne Gerin, C. Joblin, S. Wang, M. Perault, Patrick Hennebelle, Gary J. Melnick, Shanshan Yu, Peter Schilke, S. D. Lord, Paule Sonnentrucker, P. Hily-Blant, D. Johnstone, F. Boulanger, M. R. Schmidt, D. Teyssier, Raquel Monje, Alexandre Karpov, Jacob Kooi, Stephan Schlemmer, M. Salez, Peter G. Martin, David A. Neufeld, P. F. Goldsmith, Neil Trappe, M. De Luca, Karl M. Menten, Robert Kołos, F. F. S. van der Tak, Javier R. Goicoechea, Emmanuel Caux, Sébastien Maret, S.-L. Qin, Thomas R. Geballe, Cecile Gry, Neal R. Erickson, Rene Plume, Harold W. Yorke, Jesús Martín-Pintado, E. Falgarone, J. A. Murphy, Sylvie Cabrit, M. Kaźmierczak, Nathan R. Crockett, Eric Herbst, Jacek Krełowski, Charlotte Vastel, José Cernicharo, Holger S. P. Müller, P. Zaal, John C. Pearson, Carina M. Persson, Patrick W. Morris, Marie-Lise Dubernet, H. Gupta, P. J. Encrenaz, Rudolf Schieder, Fabien Daniel, Audrey Coutens, Adwin Boogert, Geoffrey A. Blake, Cecilia Ceccarelli, Edwin A. Bergin, J. Stutzki, Dariusz C. Lis, Thomas F. Giesen, Emmanuel Dartois, Bhaswati Mookerjea, Thomas G. Phillips, Laurent Pagani, Volker Ossenkopf, C. Comito, Centre d'étude spatiale des rayonnements (CESR), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Astronomy, and Faure, Alexandre

Subjects
Experimental Physics, FOS: Physical sciences, Astrophysics, 01 natural sciences, ISM: abundances, COLOGNE DATABASE, OXYGEN, 0103 physical sciences, ABSORPTION, Sagittarius B2, 010306 general physics, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, Physics, AMMONIA, CDMS, Line-of-sight, SPECTROSCOPY, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], astrochemistry, ASTRONOMY, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, ISM: molecules, molecular processes, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), MOLECULAR CLOUDS, VAPOR, submillimeter: ISM, SUBMILLIMETER
Abstract

We present Herschel/HIFI observations of the fundamental rotational transitions of ortho- and para-H$_2^{16}$O and H$_2^{18}$O in absorption towards Sagittarius~B2(M) and W31C. The ortho/para ratio in water in the foreground clouds on the line of sight towards these bright continuum sources is generally consistent with the statistical high-temperature ratio of 3, within the observational uncertainties. However, somewhat unexpectedly, we derive a low ortho/para ratio of $2.35 \pm 0.35$, corresponding to a spin temperature of $\sim$27~K, towards Sagittarius~B2(M) at velocities of the expanding molecular ring. Water molecules in this region appear to have formed with, or relaxed to, an ortho/para ratio close to the value corresponding to the local temperature of the gas and dust., Accepted for publication in A&A, HIFI Special Issue; 5 pages, 3 figures

Published
2010
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32. The Herschel-Heterodyne Instrument for the Far-Infrared (HIFI)

Author

Brian Jackson, B. Kopf, R. Bieber, R. Güsten, A. M. di Giorgio, J. A. Stern, Holger S. P. Müller, B. J. van Leeuwen, G. S. Liu, R. Orfei, Neal R. Erickson, R. Lai, B. Delforges, Wolfgang Wild, Christian Leinz, O. Coeur-Joly, J. Desbat, David Teyssier, S. D. Lord, Karl Jacobs, Bruce Bumble, Lorene Samoska, M. Rataj, R. H. Lin, Dominicus Kester, M. Salez, X. Tielens, Alexandre Karpov, Paolo Saraceno, K. Edwards, R. Huisman, A. Megej, K. F. Schuster, Michel Fich, L. Dubbeldam, Serguei Cherednichenko, H. Golstein, Christian Monstein, J. A. Murphy, C. van Baaren, Victor Belitsky, P. Planesas, E. Natale, Michael Olberg, Lorenzo Piazzo, T. Peacock, Martin Eggens, Emmanuel Caux, W. A. Hatch, Neil Trappe, Hubregt J. Visser, Herbert Zirath, Jaap Evers, S. Phillip-May, Alain Maestrini, Hamid Javadi, Jacob Kooi, Th. de Graauw, F. Schmülling, E. C. Honingh, C. McCoey, J. C. Pearson, W. Luinge, I. Lopez-Fernandez, W. M. Laauwen, M. Michalska, Bengt Larsson, S. Wulff, John Gill, René Liseau, Volker Ossenkopf, Colin Borys, B. Kruizenga, Rafael Teipen, C. Kramer, A. Cros, H. Goulooze, P. Cais, W. Nowosielski, Goutam Chattopadhyay, M. Stokroos, Rafael Bachiller, F. Zwart, C. Gal, Piotr Orleanski, J. Kawamura, H. Smit, O. Siebertz, H. Aarts, Francesco Nuzzolo, L. Meinsma, Jonas Zmuidzinas, R. Assendorp, D. A. Beintema, H. van de Stadt, Jesús Martín-Pintado, G. de Lange, Ryszard Szczerba, Erich Schlecht, R. Higgins, Christophe Risacher, Patrick W. Morris, H. Jacobs, Christopher Jarchow, Willem Jellema, Pieter Dieleman, Todd Gaier, B. Franke, J. Stutzki, Imran Mehdi, Th. Klein, Harald Franz Arno Merkel, T. Finn, M. Justen, P.R. Wesselius, M. Ciechanowicz, T. M. Klapwijk, Hans-Joachim Wunsch, C. Comito, P. Zaal, Erik L. Kollberg, C. Diez-Gonzalez, T. den Boggende, John Ward, Jian-Rong Gao, Pasquale Cerulli-Irelli, C. Kasemann, T. Kuhn, Frank Helmich, K. Wildeman, Henry G. LeDuc, L. Ravera, Frank Maiwald, Y. Delorme, D. Moratschke, F. Schlöder, J. M. Krieg, M. Olbrich, A. Marston, Juan Daniel Gallego, P.-P. Kooiman, E. Steinmetz, T. Gunsing, A. Naber, M. Melchior, Geert Keizer, M. Schultz, I. Peron, S. Gauffre, C. K. Wafelbakker, N. Whyborn, M. Krause, T. Tils, Alexander Loose, A. de Jonge, Pieter R. Roelfsema, Rudolf Schieder, M. Caris, S. Glenz, A. Barcia, W. Baechtold, Paul Hartogh, R. Shipman, Adwin Boogert, Arnold O. Benz, Thomas G. Phillips, California Institute of Technology (CALTECH), Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre d'étude spatiale des rayonnements (CESR), Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Université Sciences et Technologies - Bordeaux 1, Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology [Gothenburg, Sweden], Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Dept Pathol & Microbiol, Université de Montréal (UdeM)-Faculté de médecine vétérinaire, Leibniz Institute for Crystal Growth, Leibniz Institute, Technische Universität Darmstadt (TU Darmstadt), Instituto de RadioAstronomía Milimétrica (IRAM), Centre National de la Recherche Scientifique (CNRS), Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster (WWU), Institute of Molecular Medicine and Cell Research (ZBMZ), University of Freiburg [Freiburg], Onsala Space Observatory, Chalmers University of Technology [Göteborg], ESO, European Southern Observatory (ESO), Istituto di Fisica dello Spazio Interplanetario (IFSI), Consiglio Nazionale delle Ricerche (CNR), Max Planck Institute for Meteorology (MPI-M), Institut für Chemie und Dynamik der Geosphäre - Troposphäre (ICG-2), Forschungszentrum Jülich GmbH | Centre de recherche de Juliers, Helmholtz-Gemeinschaft = Helmholtz Association-Helmholtz-Gemeinschaft = Helmholtz Association, Herschel Science Center [Madrid], European Space Astronomy Centre (ESAC), European Space Agency (ESA)-European Space Agency (ESA), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Nice Sophia Antipolis (1965 - 2019) (UNS), École normale supérieure - Paris (ENS-PSL), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Technische Universität Darmstadt - Technical University of Darmstadt (TU Darmstadt), Westfälische Wilhelms-Universität Münster = University of Münster (WWU), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), TNO Industrie en Techniek, and Astronomy

Subjects
Experimental Physics, Local oscillator, Observatories, Orbits, general [Submillimeter], 01 natural sciences, 7. Clean energy, spectroscopic [Techniques], law.invention, Far infrared, Spectrographs, law, spectrographs [Instrumentation], 010303 astronomy & astrophysics, instrumentation: spectrographs, Physics, Spectrometers, submillimeter: general, Bolometers, Correlators, methods: observational, infrared: general, Heterodyne, Frequency band, Submillimeter: generals, Instantaneous phase, Radio spectrum, Optics, Mixers (machinery), 0103 physical sciences, Frequency bands, observational [Methods], 010306 general physics, Remote sensing, techniques: spectroscopic, Spectrometer, business.industry, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Bolometer, generals [Submillimeter], Astronomy and Astrophysics, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Launching, general [Infrared], Space and Planetary Science, Heterodyning, Instruments, business
Abstract

International audience; Aims: This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI) that was launched onboard ESA's Herschel Space Observatory in May 2009. Methods: The instrument is a set of 7 heterodyne receivers that are electronically tuneable, covering 480-1250 GHz with SIS mixers and the 1410-1910 GHz range with hot electron bolometer (HEB) mixers. The local oscillator (LO) subsystem comprises a Ka-band synthesizer followed by 14 chains of frequency multipliers and 2 chains for each frequency band. A pair of auto-correlators and a pair of acousto-optical spectrometers process the two IF signals from the dual-polarization, single-pixel front-ends to provide instantaneous frequency coverage of 2 × 4 GHz, with a set of resolutions (125 kHz to 1 MHz) that are better than 0.1 km s-1. Results: After a successful qualification and a pre-launch TB/TV test program, the flight instrument is now in-orbit and completed successfully the commissioning and performance verification phase. The in-orbit performance of the receivers matches the pre-launch sensitivities. We also report on the in-orbit performance of the receivers and some first results of HIFI's operations. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

Published
2010
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33. Detection of OH+ and H2O+ towards Orion KL

Author

Gupta, H., Rimmer, P., Pearson, J.C., Yu, S., Herbst, E., Harada, N., Bergin, E.A., Neufeld, D.A., Melnick, G.J., Bachiller, R., Bells, T.A., Blake, G.A., Caux, E., Ceccarelli, C., Cernicharo, J., Chattopadhyay, G., Comito, C., Cabrit, S., Crockett, N.R., Daniel, F., Falgarone, E., Diez-Gonzalez, M.C., Dubernet, M.-L., Erickson, N., Emprechtinger, M., Encrenaz, P., Gerin, M., Gill, J.J., Giesen, T.F., Goicoechea, J.R., Goldsmith, P.F., Joblin, C., Johnstone, D., Langer, W.D., Larsson, B., Latter, W.B., Lin, R.J., Lis, D.C., Liseau, R., Lord, S.D., Maiwald, F.W., Maret, S., Martin, P.G., Martin-Pintado, J., Menten, K.M., Morris, P., Muller, H.S.P., Murphy, J.A., Nordh, L.H., Olberg, M., Ossenkopf, V., Pagani, L., Perault, M., Phillips , T.G., Plume, R., Qin, S.-L., Salez, M., Samoska, L.A., Schilke, P., Schlecht, E., Schlemmer, S., Szczerba, R., Stutzki, J., Trappe, N., van der Tak, F.F.S., Vastel, C., Wang, S., Yorke, H.W., Zmuidzinas, J., Boogert, A., Gusten, R., Hartogh, P., Honigh, N., Karpov, A., Kooi, J., Krieg, J.-M., Schieder, R., and Zaal, P.

Subjects
Experimental Physics
Abstract

We report observations of the reactive molecular ions OH+, H2O+, and H3O+ towards Orion KL with Herschel/HIFI. All three N = 1−0 finestructure transitions of OH+ at 909, 971, and 1033 GHz and both fine-structure components of the doublet ortho-H2O+ 111−000 transition at 1115 and 1139 GHz were detected; an upper limit was obtained for H3O+. OH+ and H2O+ are observed purely in absorption, showing a narrow component at the source velocity of 9 km s−1, and a broad blueshifted absorption similar to that reported recently for HF and para-H18 2 O, and attributed to the low velocity outflow of Orion KL.We estimate column densities of OH+ and H2O+ for the 9 kms−1 component of 9±3×1012 cm−2 and 7±2×1012 cm−2, and those in the outflow of 1.9±0.7×1013 cm−2 and 1.0±0.3×1013 cm−2. Upper limits of 2.4×1012 cm−2 and 8.7×1012 cm−2 were derived for the column densities of ortho and para-H3O+ from transitions near 985 and 1657 GHz. The column densities of the three ions are up to an order of magnitude lower than those obtained from recent observations ofW31C and W49N. The comparatively low column densities may be explained by a higher gas density despite the assumption of a very high ionization rate.

Published
2010

34. C2D Spitzer-IRS spectra of disks around T Tauri stars

Author

Geers, V. C., Augereau, J.-C., Pontoppidan, K. M., Dullemond, C. P., Visser, R., Kessler-Silacci, J. E., Evans, N. J., II, van Dishoeck, E. F., Blake, G. A., Boogert, A. C. A., Brown, J. M., Lahuis, F., and Merín, B.

Abstract

Aims. We search for Polycyclic Aromatic Hydrocarbon (PAH) features towards young low-mass (T Tauri) stars and compare them with surveys of intermediate mass (Herbig Ae/Be) stars. The presence and strength of the PAH features are interpreted with disk radiative transfer models exploring the PAH feature dependence on the incident UV radiation, PAH abundance and disk parameters. Methods. Spitzer Space Telescope 5-35 µm spectra of 54 pre-main sequence stars with disks were obtained, consisting of 38 T Tauri, 7 Herbig Ae/Be and 9 stars with unknown spectral type. Results. Compact PAH emission is detected towards at least 8 sources of which 5 are Herbig Ae/Be stars. The 11.2 µm PAH feature is detected in all of these sources, as is the 6.2 µm PAH feature for the 4 sources for which short wavelength data are available. However, the 7.7 and 8.6 µm features appear strongly in only 1 of these 4 sources. Based on the 11.2 µm feature, PAH emission is observed towards at least 3 T Tauri stars, with 14 tentative detections, resulting in a lower limit to the PAH detection rate of 8%. The lowest mass source with PAH emission in our sample is T Cha with a spectral type G8. All 4 sources in our sample with evidence for dust holes in their inner disk show PAH emission, increasing the feature/continuum ratio. Typical 11.2 µm line intensities are an order of magnitude lower than those observed for the more massive Herbig Ae/Be stars. Measured line fluxes indicate PAH abundances that are factors of 10-100 lower than standard interstellar values. Conversely, PAH features from disks exposed to stars with T_(eff) ≤ 4200 K without enhanced UV are predicted to be below the current detection limit, even for high PAH abundances. Disk modeling shows that the 6.2 and 11.2 µm features are the best PAH tracers for T Tauri stars, whereas the 7.7 and 8.6 µm bands have low feature over continuum ratios due to the strongly rising silicate emission.

Published
2006

35. Stringent upper limit of CH4 on Mars based on SOFIA/EXES observations.

Author

Aoki, S., Richter, M. J., DeWitt, C., Boogert, A., Encrenaz, T., Sagawa, H., Nakagawa, H., Vandaele, A. C., Giuranna, M., Greathouse, T. K., Fouchet, T., Geminale, A., Sindoni, G., McKelvey, M., Case, M., and Kasaba, Y.

Abstract

Discovery of CH4 in the Martian atmosphere has led to much discussion since it could be a signature of biological and/or geological activities on Mars. However, the presence of CH4 and its temporal and spatial variations are still under discussion because of the large uncertainties embedded in the previous observations. We performed sensitive measurements of Martian CH4 by using the EchelonCross-Echelle Spectrograph (EXES) onboard the Stratospheric Observatory for Infrared Astronomy (SOFIA) on 16 March 2016, which corresponds to summer (Ls = 123.2 ◦ ) in the northern hemisphere on Mars. The high altitude of SOFIA (∼13.7 km) enables us to significantly reduce the effects of terrestrial atmosphere. Thanks to this, SOFIA/EXES improves our chances of detecting Martian CH4 lines because it reduces the impact of telluric CH4 on Martian CH4, and allows us to use CH4 lines in the 7.5 µm band which has less contamination. However, our results show no unambiguous detection of Martian CH4. The Martian disk was spatially resolved into 3 × 3 areas, and the upper limits on the CH4 volume mixing ratio range from 1 to 9 ppb across the Martian atmosphere, which is significantly less than detections in several other studies. These results emphasize that release of CH4 on Mars is sporadic and/or localized if the process is present. [ABSTRACT FROM AUTHOR]

Published
2018
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36. The puzzling detection of D_2CO in the molecular cloud L1689N

Author

Emmanuel Caux, Cecilia Ceccarelli, Alain Castets, Aggm Tielens, Charlotte Vastel, A. C. A. Boogert, and Laurent Loinard

Subjects
Physics, Space and Planetary Science, Molecular cloud, Ophiuchus, Molecule, Cold storage, Astronomy and Astrophysics, Astrophysics, Gas phase
Abstract

We present new observations of the D_2CO emission towards the small cloud L1689N in the ρ Ophiuchus complex. We surveyed five positions, three being a cut across a shock site and two probing the quiescent gas of the molecular cloud. We detected D_2CO emission in the first three positions. The measured [D_2CO] /[ H2CO] is about 3%, whereas it is ≤2% in the quiescent gas. We discuss the implications of these new observations, which suggest that the bulk of the D_2CO molecules is stored in grain mantles, and removed from the cold storage by the shock at the interface between the outflowing and quiescent gas. We review the predictions of the published models proposed to explain the observed high deuteration of formaldehyde. They fall in two basic schemes: gas phase and grain surface chemistry. None of the reviewed models is able to account for the observed [D_2CO] /[H_2CO] abundance ratio. A common characteristics shared by the models is apparently that all underestimate the atomic [D]/[H] ratio in the accreting gas.

Published
2002

37. Bands of solid CO_2 in the 2-3 µm spectrum of S 140:IRS1

Author

Keane, J. V., Boogert, A. C. A., Tielens, A. G. G. M., Ehrenfreund, P., and Schutte, W. A.

Abstract

We investigate the 2-3 µm ISO-SWS spectrum of the luminous protostellar object S 140:IRS1. Two narrow absorption features are detected at 2.70 and 2.77 μm, which are well fitted with laboratory spectra of the ν_1 + ν_3 and the 2ν_2 + ν_3 combination modes of solid . The ice in this line of sight must have been subjected to significant heating, in agreement with previously studied CO_2 bands. A combined laboratory fit to all CO2 bands detected toward S 140:IRS1 shows, among others, the need for particle shape calculations for the CO_2 stretch mode. Finally, we discuss the absence of features of isolated H_2O and dangling OH groups in the spectrum of S 140:IRS1.

Published
2001

38. Ice absorption features in the 5-8 μm region toward embedded protostars

Author

Douglas C. B. Whittet, Alexander G. G. M. Tielens, Adwin Boogert, W. A. Schutte, Jacqueline V. Keane, and Astronomy

Subjects
infrared : ISM, Infrared, Extinction (astronomy), Infrared spectroscopy, Astrophysics, H2O ICE, Spectral line, INFRARED-SPECTROSCOPY, ISM : molecules, MICRON SPECTRA, TIME-DEPENDENT CHEMISTRY, Absorption (electromagnetic radiation), Physics, MONOCEROS R2/IRS-3, DENSE MOLECULAR CLOUDS, Spectrometer, extinction, stars : formation, Astronomy and Astrophysics, MU-M ABSORPTION, ISM : abundances, Wavelength, SOLID-STATE, Space and Planetary Science, Absorption band, ISM : dust, extinction, ISM : dust, ORGANIC-MOLECULES, ISO-SWS OBSERVATIONS
Abstract

We have obtained 5-8 mum spectra towards 10 embedded protostars using the Short Wavelength Spectrometer on board the Infrared Space Observatory (ISO-SWS) with the aim of studying the composition of interstellar ices. The spectra are dominated by absorption bands at 6.0 mum and 6.85 mum. The observed peak positions, widths and relative intensities of these bands vary dramatically along the different lines of sight. On the basis of comparison with laboratory spectra, the bulk of the 6.0 mum absorption band is assigned to amorphous H2O ice. Additional absorption, in this band, is seen toward 5 sources on the short wavelength wing, near 5.8 mum, and the long wavelength side near 6.2 mum. We attribute the short wavelength absorption to a combination of formic acid (HCOOH) and formaldehyde (H2CO), while the long wavelength absorption has been assigned to the C-C stretching mode of aromatic structures. From an analysis of the 6.85 mum band, we conclude that this band is composed of two components: a volatile component centered near 6.75 mum and a more refractory component at 6.95 mum. From a comparison with various temperature tracers of the thermal history of interstellar ices, we conclude that the two 6.85 mum components are related through thermal processing. We explore several possible carriers of the 6.85 mum absorption band, but no satisfactory identification can be made at present. Finally, we discuss the possible implications for the origin and evolution of interstellar ices that arise from these new results.

Published
2001

39. Bands of solid CO_2 in the 2-3 mu m spectrum of S 140:IRS1

Author

Keane, J V, Boogert, A C A, Tielens, A G G M, Ehrenfreund, P, Schutte, W A, and Astronomy

Subjects
ISM : molecules, CARBON-DIOXIDE, ANALOGS, INTERSTELLAR ICES, CLOUDS, PROTOSTARS, MIXTURES, H2O, ISM : abundances, stars : S 140 : IRS1, infrared : stars, INFRARED-SPECTROSCOPY
Abstract

We investigate the 2-3 mum ISO-SWS spectrum of the luminous protostellar object S 140:IRS1. Two narrow absorption features are detected at 2.70 and 2.77 mum, which are well fitted with laboratory spectra of the nu (1) + nu (3) and the 2 nu (2) + nu (3) combination modes of solid CO2. The ice in this line of sight must have been subjected to significant heating, in agreement with previously studied CO2 bands. A combined laboratory fit to all CO2 bands detected toward S 140:IRS1 shows, among others, the need for particle shape calculations for the CO2 stretch mode. Finally, we discuss the absence of features of isolated H2O and dangling OH groups in the spectrum of S 140:IRS1.

Published
2001

40. Polarisation observations of VY Canis Majoris H2O 5 32-441 620.701 GHz maser emission with HIFI

Author

Astrophysics, Afd Astrophysics begr 1/1/17, Harwit, M., Houde, M., Sonnentrucker, P., Boogert, A. C. A., Cernicharo, J., De Beck, E., Decin, L., Henkel, C., Higgins, R. D., Jellema, W., Kraus, A., McCoey, C., Melnick, G. J., Menten, K. M., Risacher, C., Teyssier, D., Vaillancourt, J. E., Alcolea, J., Bujarrabal, V., Dominik, C., Justtanont, K., de Koter, A., Marston, A.P., Olofsson, H., Planesas, P., Schmidt, M., Schöier, F. L., Szczerba, R., Waters, L.B.F.M., Astrophysics, Afd Astrophysics begr 1/1/17, Harwit, M., Houde, M., Sonnentrucker, P., Boogert, A. C. A., Cernicharo, J., De Beck, E., Decin, L., Henkel, C., Higgins, R. D., Jellema, W., Kraus, A., McCoey, C., Melnick, G. J., Menten, K. M., Risacher, C., Teyssier, D., Vaillancourt, J. E., Alcolea, J., Bujarrabal, V., Dominik, C., Justtanont, K., de Koter, A., Marston, A.P., Olofsson, H., Planesas, P., Schmidt, M., Schöier, F. L., Szczerba, R., and Waters, L.B.F.M.

Published
2010

41. Herschel observations of EXtra-Ordinary Sources (HEXOS): detecting spiral arm clouds by CH absorption lines

Author

Qin, S.-L., Schilke, P., Comito, C., Moller, T., Rolff, R., Muller, H.S.P., Belloche, A., Menten, K.M., Lis, D.C., Phillips , T.G., Bergin, E.A., Bell, T.A., Crockett, N.R., Blake, G.A., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Daniel, F., Dubernet, M.-L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T.F., Goicoechea, J.R., Goldsmith, P.F., Gupta, H., Herbst, E., Joblin, C., Johnstone, D., Langer, W.D., Lord, S.D., Maret, S., Martin, P.G., Melnick, G.J., Morris, P., Murphy, J.Anthony, Neufeld, D.A., Ossenkopf, V., Pagani, L., Pearson, J.C., Perault, M., Plume, R., Salez, M., Schlemmer, S., Stutzki, J., Trappe, Neil, van der Tak, F.F.S., Vastel, C., Wang, S., Yorke, H.W., Yu, S., Zmuidzinas, J., Boogert, A., Gusten, R., Hartogh, P., Honingh, E., Karpov, A., Kooi, J., Krieg, J.-M., Schieder, R., Diez-Gonzalez, M.C., Bachiller, R., Martin-Pintado, J., Baechtold, W., Olberg, M., Nordh, L.H., Gill, J.L., Chattopadhyay, G., Qin, S.-L., Schilke, P., Comito, C., Moller, T., Rolff, R., Muller, H.S.P., Belloche, A., Menten, K.M., Lis, D.C., Phillips , T.G., Bergin, E.A., Bell, T.A., Crockett, N.R., Blake, G.A., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Daniel, F., Dubernet, M.-L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T.F., Goicoechea, J.R., Goldsmith, P.F., Gupta, H., Herbst, E., Joblin, C., Johnstone, D., Langer, W.D., Lord, S.D., Maret, S., Martin, P.G., Melnick, G.J., Morris, P., Murphy, J.Anthony, Neufeld, D.A., Ossenkopf, V., Pagani, L., Pearson, J.C., Perault, M., Plume, R., Salez, M., Schlemmer, S., Stutzki, J., Trappe, Neil, van der Tak, F.F.S., Vastel, C., Wang, S., Yorke, H.W., Yu, S., Zmuidzinas, J., Boogert, A., Gusten, R., Hartogh, P., Honingh, E., Karpov, A., Kooi, J., Krieg, J.-M., Schieder, R., Diez-Gonzalez, M.C., Bachiller, R., Martin-Pintado, J., Baechtold, W., Olberg, M., Nordh, L.H., Gill, J.L., and Chattopadhyay, G.

Abstract

We have observed CH absorption lines (J = 3/2, N = 1 ← J = 1/2, N = 1) against the continuum source Sgr B2(M) using the Herschel/HIFI instrument. With the high spectral resolution and wide velocity coverage provided by HIFI, 31 CH absorption features with different radial velocities and line widths are detected and identified. The narrower line width and lower column density clouds show “spiral arm” cloud characteristics, while the absorption component with the broadest line width and highest column density corresponds to the gas from the Sgr B2 envelope. The observations show that each “spiral arm” harbors multiple velocity components, indicating that the clouds are not uniform and that they have internal structure. This line-of-sight through almost the entire Galaxy offers unique possibilities to study the basic chemistry of simple molecules in diffuse clouds, as a variety of different cloud classes are sampled simultaneously. We find that the linear relationship between CH and H2 column densities found at lower AV by UV observations does not continue into the range of higher visual extinction. There, the curve flattens, which probably means that CH is depleted in the denser cores of these clouds.

Published
2010

42. Herschel/HIFI measurements of the ortho/para ratio in water towards Sagittarius B2(M) and W31C

Author

Lis, D.C., Phillips, T.G., Goldsmith, P.F., Neufeld, D.A., Herbst, E., Comito, C., Schilke, P., Muller, H.S.P., Bergin, E.A., Gerin, M., Bell, T.A., Emprechtinger, M., Black, J., Blake, G.A., Boulanger, F., Caux, E., Ceccarelli, C., Cernicharo, J., Coutens, A., Crockett, N.R., Daniel, F., Dartois, E., De Luca, M., Dubernet, M.-L., Encrenaz, P., Falgarone, E., Geballe, T.R., Godard, B., Giesen, T.F., Goicoechea, J.R., Gry, C., Gupta, H., Hennebelle, P., Hily-Blant, P., Kolos, R., Krelowski, J., Joblin, C., Johnstone, D., Kazmierczak, M., Lord, S.D., Maret, S., Martin, P.G., Martin-Pintado, J., Melnick, G.J., Menten, K.M., Monjel, R., Mookerjea, B., Morris, P., Murphy, J.Anthony, Ossenkopf, V., Pearson, J.C., Perault, M., Persson, C., Plume, R., Qin, S.-L., Salez, M., Schlemmer, S., Schmidt, M., Sonnentrucker, P., Stutzki, J., Teyssier, D., Trappe, Neil, van der Tak, F.F.S., Vastel, C., Wang, S., Yorke, H.W., Yu, S., Zmuidzinas, J., Boogert, A., Erickson, N., Karpov, A., Kooi, J., Maiwald, F.W., Schieder, R., Zaal, P., Lis, D.C., Phillips, T.G., Goldsmith, P.F., Neufeld, D.A., Herbst, E., Comito, C., Schilke, P., Muller, H.S.P., Bergin, E.A., Gerin, M., Bell, T.A., Emprechtinger, M., Black, J., Blake, G.A., Boulanger, F., Caux, E., Ceccarelli, C., Cernicharo, J., Coutens, A., Crockett, N.R., Daniel, F., Dartois, E., De Luca, M., Dubernet, M.-L., Encrenaz, P., Falgarone, E., Geballe, T.R., Godard, B., Giesen, T.F., Goicoechea, J.R., Gry, C., Gupta, H., Hennebelle, P., Hily-Blant, P., Kolos, R., Krelowski, J., Joblin, C., Johnstone, D., Kazmierczak, M., Lord, S.D., Maret, S., Martin, P.G., Martin-Pintado, J., Melnick, G.J., Menten, K.M., Monjel, R., Mookerjea, B., Morris, P., Murphy, J.Anthony, Ossenkopf, V., Pearson, J.C., Perault, M., Persson, C., Plume, R., Qin, S.-L., Salez, M., Schlemmer, S., Schmidt, M., Sonnentrucker, P., Stutzki, J., Teyssier, D., Trappe, Neil, van der Tak, F.F.S., Vastel, C., Wang, S., Yorke, H.W., Yu, S., Zmuidzinas, J., Boogert, A., Erickson, N., Karpov, A., Kooi, J., Maiwald, F.W., Schieder, R., and Zaal, P.

Abstract

We present Herschel/HIFI observations of the fundamental rotational transitions of ortho- and para-H16 2 O and H18 2 O in absorption towards Sagittarius B2(M) and W31C. The ortho/para ratio in water in the foreground clouds on the line of sight towards these bright continuum sources is generally consistent with the statistical high-temperature ratio of 3, within the observational uncertainties. However, somewhat unexpectedly, we derive a low ortho/para ratio of 2.35±0.35, corresponding to a spin temperature of ∼27 K, towards Sagittarius B2(M) at velocities of the expanding molecular ring. Water molecules in this region appear to have formed with, or relaxed to, an ortho/para ratio close to the value corresponding to the local temperature of the gas and dust.

Published
2010

43. Herschel/HIFI discovery of interstellar chloronium (H2Cl+)

Author

Lis, D.C., Pearson, J.C., Neufeld, D.A., Schilke, P., Muller, H.S.P., Gupta, H., Bell, T.A., Comito, C., Phillips , T.G., Bergin, E.A., Ceccarelli, C., Goldsmith, P.F., Blake, G.A., Bacmann, A., Baudry, A., Benedettini, M., Benz, A.O., Black, J., Boogert, A., Bottinelli, S., Cabrit, S., Caselli, P., Castets, A., Caux, E., Cernicharo, J., Codella, C., Coutens, A., Crimier, N., Crockett, N.R., Daniel, F., Demyk, K., Dominic, C., Dubernet, M.-L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Fuente, A., Gerin, M., Giesen, T.F., Goicoechea, J.R., Helmich, F., Hennebelle, P., Henning, Th., Herbst, E., Hily-Blant, P., Hjalmarson, A., Hollenbach, D., Jack, T., Joblin, C., Johnstone, D., Kahane, C., Kama, M., Kaufman, M., Klotz, A., Langer, W.D., Larsson, B., Le Bourlot, J., Lefloch, B., Le Petit, F., Li, D., Liseau, R., Lord, S.D., Lorenzani, A., Maret, S., Martin, P.G., Melnick, G.J., Menten, K.M., Morris, P., Murphy, J.Anthony, Nagy, Z., Nisini, B., Ossenkopf, V., Pacheco, S., Pagani, L., Parise, B., Perault, M., Plume, R., Qin, S.-L., Roueff, E., Salez, M., Sandqvist, A., Saraceno, P., Schlemmer, S., Schuster, K., Snell, R., Stutzki, J., Tielens, A., Trappe, Neil, van der Tak, F.F.S., van der Wiel, M., van Dishoeck, E.F., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wang, S., Wyrowski, F., Yorke, H.W., Yu, S., Zmuidzinas, J., Delorme, Y., Desbat, J.-P., Gustens, R., Krieg, J.-M., Delforge, B., Lis, D.C., Pearson, J.C., Neufeld, D.A., Schilke, P., Muller, H.S.P., Gupta, H., Bell, T.A., Comito, C., Phillips , T.G., Bergin, E.A., Ceccarelli, C., Goldsmith, P.F., Blake, G.A., Bacmann, A., Baudry, A., Benedettini, M., Benz, A.O., Black, J., Boogert, A., Bottinelli, S., Cabrit, S., Caselli, P., Castets, A., Caux, E., Cernicharo, J., Codella, C., Coutens, A., Crimier, N., Crockett, N.R., Daniel, F., Demyk, K., Dominic, C., Dubernet, M.-L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Fuente, A., Gerin, M., Giesen, T.F., Goicoechea, J.R., Helmich, F., Hennebelle, P., Henning, Th., Herbst, E., Hily-Blant, P., Hjalmarson, A., Hollenbach, D., Jack, T., Joblin, C., Johnstone, D., Kahane, C., Kama, M., Kaufman, M., Klotz, A., Langer, W.D., Larsson, B., Le Bourlot, J., Lefloch, B., Le Petit, F., Li, D., Liseau, R., Lord, S.D., Lorenzani, A., Maret, S., Martin, P.G., Melnick, G.J., Menten, K.M., Morris, P., Murphy, J.Anthony, Nagy, Z., Nisini, B., Ossenkopf, V., Pacheco, S., Pagani, L., Parise, B., Perault, M., Plume, R., Qin, S.-L., Roueff, E., Salez, M., Sandqvist, A., Saraceno, P., Schlemmer, S., Schuster, K., Snell, R., Stutzki, J., Tielens, A., Trappe, Neil, van der Tak, F.F.S., van der Wiel, M., van Dishoeck, E.F., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wang, S., Wyrowski, F., Yorke, H.W., Yu, S., Zmuidzinas, J., Delorme, Y., Desbat, J.-P., Gustens, R., Krieg, J.-M., and Delforge, B.

Abstract

We report the first detection of chloronium, H2Cl+, in the interstellar medium, using the HIFI instrument aboard the Herschel Space Observatory. The 212−101 lines of ortho-H35 2 Cl+ and ortho-H37 2 Cl+ are detected in absorption towards NGC 6334I, and the 111−000 transition of para-H35 2 Cl+ is detected in absorption towards NGC 6334I and Sgr B2(S). The H2Cl+ column densities are compared to those of the chemically-related species HCl. The derived HCl/H2Cl+ column density ratios, ∼1–10, are within the range predicted by models of diffuse and dense photon dominated regions (PDRs). However, the observed H2Cl+ column densities, in excess of 1013 cm−2, are significantly higher than the model predictions. Our observations demonstrate the outstanding spectroscopic capabilities of HIFI for detecting new interstellar molecules and providing key constraints for astrochemical models.

Published
2010

44. Herschel observations of ortho- and para-oxidaniumyl (H2O+) in spiral arm clouds toward Sagittarius B2(M)

Author

Schilke, P., Comito, C., Muller, H.S.P., Bergin, E.A., Herbst, E., Lis, D.C., Neufeld, D.A., Phillips , T.G., Bell, T.A., Blake, G.A., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Crockett, N.R., Daniel, F., Dubernet, M.-L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T.F., Goicoechea, J.R., Goldsmith, P.F., Gupta, H., Joblin, C., Johnstone, D., Langer, W.D., Latter, W.B., Lord, S.D., Maret, S., Martin, P.G., Melnick, G.J., Menten, K.M., Morris, P., Murphy, J.Anthony, Ossenkopf, V., Pagini, L., Pearson, J.C., Perault, M., Plume, R., Qin, S.-L., Salez, M., Schlemmer, S., Stutzki, J., Trappe, Neil, van der Tak, F.F.S., Vastel, C., Wang, S., Yorke, H.W., Yu, S., Erickson, N., Maiwald, F.W., Kooi, J., Karpov, A., Zmuidzinas, J., Boogert, A., Schieder, R., Zaal, P., Schilke, P., Comito, C., Muller, H.S.P., Bergin, E.A., Herbst, E., Lis, D.C., Neufeld, D.A., Phillips , T.G., Bell, T.A., Blake, G.A., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Crockett, N.R., Daniel, F., Dubernet, M.-L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T.F., Goicoechea, J.R., Goldsmith, P.F., Gupta, H., Joblin, C., Johnstone, D., Langer, W.D., Latter, W.B., Lord, S.D., Maret, S., Martin, P.G., Melnick, G.J., Menten, K.M., Morris, P., Murphy, J.Anthony, Ossenkopf, V., Pagini, L., Pearson, J.C., Perault, M., Plume, R., Qin, S.-L., Salez, M., Schlemmer, S., Stutzki, J., Trappe, Neil, van der Tak, F.F.S., Vastel, C., Wang, S., Yorke, H.W., Yu, S., Erickson, N., Maiwald, F.W., Kooi, J., Karpov, A., Zmuidzinas, J., Boogert, A., Schieder, R., and Zaal, P.

Abstract

H2O+ has been observed in its ortho- and para- states toward the massive star forming core Sgr B2(M), located close to the Galactic center. The observations show absorption in all spiral arm clouds between the Sun and Sgr B2. The average o/p ratio of H2O+ in most velocity intervals is 4.8, which corresponds to a nuclear spin temperature of 21 K. The relationship of this spin temperature to the formation temperature and current physical temperature of the gas hosting H2O+ is discussed, but no firm conclusion is reached. In the velocity interval 0–60 km s−1, an ortho/para ratio of below unity is found, but if this is due to an artifact of contamination by other species or real is not clear.

Published
2010

45. Herschel observations of EXtra-Ordinary Sources (HEXOS): The Terahertz spectrum of Orion KL seen at high spectral resolution

Author

Crockett, N.R., Bergin, E.A., Wang, S., Lis, D.C., Bell, T.A., Blake, G.A., Boogert, A., Bumble, B., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Comito, C., Daniel, F., Dubernet, M.-L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T.F., Goicoechea, J.R., Goldsmith, P.F., Gupta, H., Gusten, R., Hartogh, P., Helmich, F., Herbst, E., Honingh, E., Joblin, C., Johnstone, D., Karpov, A., Kawamura, J., Kooi, J., Krieg, J.-M., Langer, W., Latter, W.B., Lord, S.D., Maret, S., Martin, P.G., Melnick, G.J., Menten, K.M., Morris, P., Muller, H.S.P., Murphy, J.Anthony, Neufeld, D.A., Ossenkopf, V., Pearson, J.C., Perault, M., Phillips , T.G., Plume, R., Qin, S.-L., Roelfsema, P.R., Schieder, R., Schilke, P., Schlemmer, S., Stutzki, J., van der Tak, F.F.S., Tielens, A., Trappe, Neil, Vastel, C., Yorke, H.W., Yu, S., Zmuidzinas, J., Crockett, N.R., Bergin, E.A., Wang, S., Lis, D.C., Bell, T.A., Blake, G.A., Boogert, A., Bumble, B., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Comito, C., Daniel, F., Dubernet, M.-L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T.F., Goicoechea, J.R., Goldsmith, P.F., Gupta, H., Gusten, R., Hartogh, P., Helmich, F., Herbst, E., Honingh, E., Joblin, C., Johnstone, D., Karpov, A., Kawamura, J., Kooi, J., Krieg, J.-M., Langer, W., Latter, W.B., Lord, S.D., Maret, S., Martin, P.G., Melnick, G.J., Menten, K.M., Morris, P., Muller, H.S.P., Murphy, J.Anthony, Neufeld, D.A., Ossenkopf, V., Pearson, J.C., Perault, M., Phillips , T.G., Plume, R., Qin, S.-L., Roelfsema, P.R., Schieder, R., Schilke, P., Schlemmer, S., Stutzki, J., van der Tak, F.F.S., Tielens, A., Trappe, Neil, Vastel, C., Yorke, H.W., Yu, S., and Zmuidzinas, J.

Abstract

We present the first high spectral resolution observations of Orion KL in the frequency ranges 1573.4–1702.8 GHz (band 6b) and 1788.4–1906.8 GHz (band 7b) obtained using the HIFI instrument on board the Herschel Space Observatory. We characterize the main emission lines found in the spectrum, which primarily arise from a range of components associated with Orion KL including the hot core, but also see widespread emission from components associated with molecular outflows traced by H2O, SO2, and OH. We find that the density of observed emission lines is significantly diminished in these bands compared to lower frequency Herschel/HIFI bands.

Published
2010

46. The Herschel-Heterodyne Instrument for the Far-Infrared (HIFI)

Author

de Graauw, Th., Helmich, F.P., Phillips , T.G., Stutzki, J., Caux, E., Whyborn, N.D., Dieleman, P., Roelfsema, P.R., Aarts, H., Assendorp, R., Bachiller, R., Baechtold, W., Barcia, A., Beintema, D.A., Belitsky, V., Benz, A.O., Bieber, R., Boogert, A., Borys, C., Bumble, B., Cais, P., Caris, M., Cerulli-Irelli, P., Chattopadhyay, G., Cherednichenko, S., Ciechanowicz, M., Coeur-Joly, O., Comito, C., Cros, A., de Jonge, A., de Lange, G., Delforges, B., Delorme, Y., den Boggende, T., Desbat, J.-M., Diez-Gonzalez, C., Di Giorgio, A.M., Dubbeldam, L., Edwards, K., Eggens, M., Erickson, N., Evers, J., Fich, M., Finn, T., Franke, B., Gaier, T., Gal, C., Gao, J.R., Gallego, J.-D., Gauffre, S., Gill, J.J., Glenz, S., Golstein, H., Goulooze, H., Gunsing, T., Gusten, R., Hartogh, P., Hatch, W.A., Higgins, R., Honingh, E.C., Huisman, R., Jackson, B.D., Jacobs, H., Jacobs, K., Jarchow, C., Javadi, H., Jellema, W., Justen, M., Karpov, A., Kasemann, C., Kawamura, J., Keizer, G., Kester, D., Klapwijk, T.M., Klein, Th., Kollberg, E., Kooi, J., Kooiman, P.-P., Kopf, B., Krause, M., Krieg, J.-M., Kramer, C., Kruizenga, B., Kuhn, T., Laauwen, W., Lai, R., Larsson, B., Leduc, H.G., Leinz, C., Lin, R.H., Liseau, R., Liu, G.S., Loose, A., Lopez-Fernandez, I., Lord, S., Luinge, W., Marston, A., Martin-Pintado, J., Maestrini, A., Maiwald, F.W., McCoey, C., Mehdi, I., Megej, A., Melchior, M., Meinsma, L., Merkel, H., Michalska, M., Monstein, C., Moratschke, D., Morris, P., Muller, H., Murphy, J.Anthony, Naber, A., Natale, E., Nowosielski, W., Nuzzolo, F., Olberg, M., Olbrich, M., Orfei, R., Orleanski, P., Ossenkopf, V., Peacock, T., Pearson, J.C., Peron, I., Phillip-May, S., Piazzo, L., Planesas, P., Rataj, M., Ravera, L., Risacher, C., Salez, M., Samoska, L.A., Saraceno, P., Schieder, R., Schlecht, E., Schloder, F., Schmulling, F., Schultz, M., Schuster, K., Siebertz, O., Smit, H., Szczerba, R., Shipman, R., Steinmetz, E., Stern, J.A., Stokroos, M., Teipen, R., Teyssier, D., Tils, T., Trappe, Neil, van Baaren, C., van Leeuwen, B.-J., van de Stadt, H., Visser, H., Wildeman, K.J., Wafelbakker, C.K., Ward, J.S., Wesselius, P., Wild, W., Wulff, S., Wunsch, H.-J., Tielens, X., Zaal, P., Zirath, H., Zmuidzinas, J., Zwart, F., de Graauw, Th., Helmich, F.P., Phillips , T.G., Stutzki, J., Caux, E., Whyborn, N.D., Dieleman, P., Roelfsema, P.R., Aarts, H., Assendorp, R., Bachiller, R., Baechtold, W., Barcia, A., Beintema, D.A., Belitsky, V., Benz, A.O., Bieber, R., Boogert, A., Borys, C., Bumble, B., Cais, P., Caris, M., Cerulli-Irelli, P., Chattopadhyay, G., Cherednichenko, S., Ciechanowicz, M., Coeur-Joly, O., Comito, C., Cros, A., de Jonge, A., de Lange, G., Delforges, B., Delorme, Y., den Boggende, T., Desbat, J.-M., Diez-Gonzalez, C., Di Giorgio, A.M., Dubbeldam, L., Edwards, K., Eggens, M., Erickson, N., Evers, J., Fich, M., Finn, T., Franke, B., Gaier, T., Gal, C., Gao, J.R., Gallego, J.-D., Gauffre, S., Gill, J.J., Glenz, S., Golstein, H., Goulooze, H., Gunsing, T., Gusten, R., Hartogh, P., Hatch, W.A., Higgins, R., Honingh, E.C., Huisman, R., Jackson, B.D., Jacobs, H., Jacobs, K., Jarchow, C., Javadi, H., Jellema, W., Justen, M., Karpov, A., Kasemann, C., Kawamura, J., Keizer, G., Kester, D., Klapwijk, T.M., Klein, Th., Kollberg, E., Kooi, J., Kooiman, P.-P., Kopf, B., Krause, M., Krieg, J.-M., Kramer, C., Kruizenga, B., Kuhn, T., Laauwen, W., Lai, R., Larsson, B., Leduc, H.G., Leinz, C., Lin, R.H., Liseau, R., Liu, G.S., Loose, A., Lopez-Fernandez, I., Lord, S., Luinge, W., Marston, A., Martin-Pintado, J., Maestrini, A., Maiwald, F.W., McCoey, C., Mehdi, I., Megej, A., Melchior, M., Meinsma, L., Merkel, H., Michalska, M., Monstein, C., Moratschke, D., Morris, P., Muller, H., Murphy, J.Anthony, Naber, A., Natale, E., Nowosielski, W., Nuzzolo, F., Olberg, M., Olbrich, M., Orfei, R., Orleanski, P., Ossenkopf, V., Peacock, T., Pearson, J.C., Peron, I., Phillip-May, S., Piazzo, L., Planesas, P., Rataj, M., Ravera, L., Risacher, C., Salez, M., Samoska, L.A., Saraceno, P., Schieder, R., Schlecht, E., Schloder, F., Schmulling, F., Schultz, M., Schuster, K., Siebertz, O., Smit, H., Szczerba, R., Shipman, R., Steinmetz, E., Stern, J.A., Stokroos, M., Teipen, R., Teyssier, D., Tils, T., Trappe, Neil, van Baaren, C., van Leeuwen, B.-J., van de Stadt, H., Visser, H., Wildeman, K.J., Wafelbakker, C.K., Ward, J.S., Wesselius, P., Wild, W., Wulff, S., Wunsch, H.-J., Tielens, X., Zaal, P., Zirath, H., Zmuidzinas, J., and Zwart, F.

Abstract

Aims. This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI) that was launched onboard ESA’s Herschel Space Observatory in May 2009. Methods. The instrument is a set of 7 heterodyne receivers that are electronically tuneable, covering 480−1250 GHz with SIS mixers and the 1410−1910 GHz range with hot electron bolometer (HEB) mixers. The local oscillator (LO) subsystem comprises a Ka-band synthesizer followed by 14 chains of frequency multipliers and 2 chains for each frequency band. A pair of auto-correlators and a pair of acousto-optical spectrometers process the two IF signals from the dual-polarization, single-pixel front-ends to provide instantaneous frequency coverage of 2 × 4 GHz, with a set of resolutions (125 kHz to 1 MHz) that are better than 0.1 kms−1. Results. After a successful qualification and a pre-launch TB/TV test program, the flight instrument is now in-orbit and completed successfully the commissioning and performance verification phase. The in-orbit performance of the receivers matches the pre-launch sensitivities. We also report on the in-orbit performance of the receivers and some first results of HIFI’s operations.

Published
2010

47. Herschel observations of EXtra-Ordinary Sources (HEXOS): Detection of hydrogen fluoride in absorption towards Orion KL

Author

Phillips , T.G., Bergin, E.A., Lis, D.C., Neufeld, D.A., Bell, T.A., Wang, S., Crockett, N.R., Emprechtinger, M., Blake, G.A., Caux, E., Ceccarelli, C., Cernicharo, J., Comito, C., Daniel, F., Dubernet, M.-L., Encrenaz, P., Gerin, M., Giesen, T.F., Goicoechea, J.R., Goldsmith, P.F., Herbst, E., Joblin, C., Johnstone, D., Langer, W.D., Latter, W.D., Lord, S.D., Maret, S., Martin, P.G., Melnick, G.J., Menten, K.M., Morris, P., Muller, H.S.P., Murphy, J.Anthony, Ossenkopf, V., Pearson, J.C., Perault, M., Plume, R., Qin, S.-L., Schilke, P., Schlemmer, S., Stutzki, J., Trappe, Neil, van der Tak, F.F.S., Vastel, C., Yorke, H.W., Yu, S., Zmuidzinas, J., Boogert, A., Gusten, R., Hartogh, P., Honingh, N., Kooi, J., Karpov, A., Krieg, J.-M., Schieder, R., Phillips , T.G., Bergin, E.A., Lis, D.C., Neufeld, D.A., Bell, T.A., Wang, S., Crockett, N.R., Emprechtinger, M., Blake, G.A., Caux, E., Ceccarelli, C., Cernicharo, J., Comito, C., Daniel, F., Dubernet, M.-L., Encrenaz, P., Gerin, M., Giesen, T.F., Goicoechea, J.R., Goldsmith, P.F., Herbst, E., Joblin, C., Johnstone, D., Langer, W.D., Latter, W.D., Lord, S.D., Maret, S., Martin, P.G., Melnick, G.J., Menten, K.M., Morris, P., Muller, H.S.P., Murphy, J.Anthony, Ossenkopf, V., Pearson, J.C., Perault, M., Plume, R., Qin, S.-L., Schilke, P., Schlemmer, S., Stutzki, J., Trappe, Neil, van der Tak, F.F.S., Vastel, C., Yorke, H.W., Yu, S., Zmuidzinas, J., Boogert, A., Gusten, R., Hartogh, P., Honingh, N., Kooi, J., Karpov, A., Krieg, J.-M., and Schieder, R.

Abstract

We report a detection of the fundamental rotational transition of hydrogen fluoride in absorption towards Orion KL using Herschel/HIFI. After the removal of contaminating features associated with common molecules (“weeds”), the HF spectrum shows a P-Cygni profile, with weak redshifted emission and strong blue-shifted absorption, associated with the low-velocity molecular outflow. We derive an estimate of 2.9 × 1013 cm−2 for the HF column density responsible for the broad absorption component. Using our best estimate of the H2 column density within the low-velocity molecular outflow, we obtain a lower limit of ∼1.6 × 10−10 for the HF abundance relative to hydrogen nuclei, corresponding to ∼0.6% of the solar abundance of fluorine. This value is close to that inferred from previous ISO observations of HF J = 2−1 absorption towards Sgr B2, but is in sharp contrast to the lower limit of 6 × 10−9 derived by Neufeld et al. for cold, foreground clouds on the line of sight towards G10.6-0.4.

Published
2010

48. Deuterated water in the solar-type protostars NGC 1333 IRAS 4A and IRAS 4B

Author

Coutens, A., primary, Vastel, C., additional, Cabrit, S., additional, Codella, C., additional, Kristensen, L. E., additional, Ceccarelli, C., additional, van Dishoeck, E. F., additional, Boogert, A. C. A., additional, Bottinelli, S., additional, Castets, A., additional, Caux, E., additional, Comito, C., additional, Demyk, K., additional, Herpin, F., additional, Lefloch, B., additional, McCoey, C., additional, Mottram, J. C., additional, Parise, B., additional, Taquet, V., additional, van der Tak, F. F. S., additional, Visser, R., additional, and Yıldız, U. A., additional

Published
2013
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49. In-orbit performance ofHerschel-HIFI

Author

Roelfsema, P. R., primary, Helmich, F. P., additional, Teyssier, D., additional, Ossenkopf, V., additional, Morris, P., additional, Olberg, M., additional, Shipman, R., additional, Risacher, C., additional, Akyilmaz, M., additional, Assendorp, R., additional, Avruch, I. M., additional, Beintema, D., additional, Biver, N., additional, Boogert, A., additional, Borys, C., additional, Braine, J., additional, Caris, M., additional, Caux, E., additional, Cernicharo, J., additional, Coeur-Joly, O., additional, Comito, C., additional, de Lange, G., additional, Delforge, B., additional, Dieleman, P., additional, Dubbeldam, L., additional, de Graauw, Th., additional, Edwards, K., additional, Fich, M., additional, Flederus, F., additional, Gal, C., additional, di Giorgio, A., additional, Herpin, F., additional, Higgins, D. R., additional, Hoac, A., additional, Huisman, R., additional, Jarchow, C., additional, Jellema, W., additional, de Jonge, A., additional, Kester, D., additional, Klein, T., additional, Kooi, J., additional, Kramer, C., additional, Laauwen, W., additional, Larsson, B., additional, Leinz, C., additional, Lord, S., additional, Lorenzani, A., additional, Luinge, W., additional, Marston, A., additional, Martín-Pintado, J., additional, McCoey, C., additional, Melchior, M., additional, Michalska, M., additional, Moreno, R., additional, Müller, H., additional, Nowosielski, W., additional, Okada, Y., additional, Orleański, P., additional, Phillips, T. G., additional, Pearson, J., additional, Rabois, D., additional, Ravera, L., additional, Rector, J., additional, Rengel, M., additional, Sagawa, H., additional, Salomons, W., additional, Sánchez-Suárez, E., additional, Schieder, R., additional, Schlöder, F., additional, Schmülling, F., additional, Soldati, M., additional, Stutzki, J., additional, Thomas, B., additional, Tielens, A. G. G. M., additional, Vastel, C., additional, Wildeman, K., additional, Xie, Q., additional, Xilouris, M., additional, Wafelbakker, C., additional, Whyborn, N., additional, Zaal, P., additional, Bell, T., additional, Bjerkeli, P., additional, de Beck, E., additional, Cavalié, T., additional, Crockett, N. R., additional, Hily-Blant, P., additional, Kama, M., additional, Kaminski, T., additional, Leflóch, B., additional, Lombaert, R., additional, De Luca, M., additional, Makai, Z., additional, Marseille, M., additional, Nagy, Z., additional, Pacheco, S., additional, van der Wiel, M. H. D., additional, Wang, S., additional, and Yıldız, U., additional

Published
2011
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