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1. Evidence for Surprising Heavy Nitrogen Isotopic Enrichment in Comet 46P/Wirtanen’s Hydrogen Cyanide

Author

M. A. Cordiner, K. Darnell, D. Bockelée-Morvan, N. X. Roth, N. Biver, S. N. Milam, S. B. Charnley, J. Boissier, B. P. Bonev, C. Qi, J. Crovisier, and A. J. Remijan

Subjects
Comets, Neutral coma gases, Comae, Small Solar System bodies, Astrochemistry, Cosmochemistry, Astronomy, QB1-991
Abstract

46P/Wirtanen is a Jupiter-family comet, probably originating from the solar system’s Kuiper Belt, that now resides on a 5.4 yr elliptical orbit. During its 2018 apparition, comet 46P passed unusually close to the Earth (within 0.08 au), presenting an outstanding opportunity for close-up observations of its inner coma. Here we present observations of HCN, H ^13 CN, and HC ^15 N emission from 46P using the Atacama Compact Array. The data were analyzed using the SUBLIME non-LTE radiative transfer code to derive ^12 C/ ^13 C and ^14 N/ ^15 N ratios. The HCN/H ^13 CN ratio is found to be consistent with a lack of significant ^13 C fractionation, whereas the HCN/HC ^15 N ratio of 68 ± 27 (using our most conservative 1 σ uncertainties), indicates a strong enhancement in ^15 N compared with the solar and terrestrial values. The observed ^14 N/ ^15 N ratio is also significantly lower than the values of ∼140 found in previous comets, implying a strong ^15 N enrichment in 46P’s HCN. This indicates that the nitrogen in Jupiter-family comets could reach larger isotopic enrichments than previously thought, with implications for the diversity of ^14 N/ ^15 N ratios imprinted into icy bodies at the birth of the solar system.

Published
2024
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2. Gas Sources from the Coma and Nucleus of Comet 46P/Wirtanen Observed Using ALMA

Author

M. A. Cordiner, N. X. Roth, S. N. Milam, G. L. Villanueva, D. Bockelée-Morvan, A. J. Remijan, S. B. Charnley, N. Biver, D. C. Lis, C. Qi, B. P. Bonev, J. Crovisier, and J. Boissier

Subjects
Short period comets, Comet volatiles, Interstellar molecules, Radio interferometry, Millimeter-wave spectroscopy, Molecular spectroscopy, Astrophysics, QB460-466
Abstract

Gas-phase molecules in cometary atmospheres (comae) originate primarily from (1) outgassing by the nucleus, (2) sublimation of icy grains in the near-nucleus coma, and (3) coma (photo)chemical processes. However, the majority of cometary gases observed at radio wavelengths have yet to be mapped, so their production/release mechanisms remain uncertain. Here we present observations of six molecular species toward comet 46P/Wirtanen, obtained using the Atacama Large Millimeter/submillimeter Array during the comet’s unusually close (∼0.1 au) approach to Earth in 2018 December. Interferometric maps of HCN, CH _3 OH, CH _3 CN, H _2 CO, CS, and HNC were obtained at an unprecedented sky-projected spatial resolution of up to 25 km, enabling the nucleus and coma sources of these molecules to be accurately quantified. The HCN, CH _3 OH, and CH _3 CN spatial distributions are consistent with production by direct outgassing from (or very close to) the nucleus, with a significant proportion of the observed CH _3 OH originating from sublimation of icy grains in the near-nucleus coma (at a scale length L _p = 36 ± 7 km). On the other hand, H _2 CO, CS, and HNC originate primarily from distributed coma sources (with L _p values in the range 550–16,000 km), the identities of which remain to be established. The HCN, CH _3 OH, and HNC abundances in 46P are consistent with the average values previously observed in comets, whereas the H _2 CO, CH _3 CN, and CS abundances are relatively low.

Published
2023
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3. The organic-rich surface of comet 67P/Churyumov-Gerasimenko as seen by VIRTIS/Rosetta

Author

F. Capaccioni, A. Coradini, G. Filacchione, S. Erard, G. Arnold, P. Drossart, M. C. De Sanctis, D. Bockelee-Morvan, M. T. Capria, F. Tosi, C. Leyrat, B. Schmitt, E. Quirico, P. Cerroni, V. Mennella, A. Raponi, M. Ciarniello, T. McCord, L. Moroz, E. Palomba, E. Ammannito, M. A. Barucci, G. Bellucci, J. Benkhoff, J. P. Bibring, A. Blanco, M. Blecka, R. Carlson, U. Carsenty, L. Colangeli, M. Combes, M. Combi, J. Crovisier, T. Encrenaz, C. Federico, U. Fink, S. Fonti, W. H. Ip, P. Irwin, R. Jaumann, E. Kuehrt, Y. Langevin, G. Magni, S. Mottola, V. Orofino, P. Palumbo, G. Piccioni, U. Schade, F. Taylor, D. Tiphene, G. P. Tozzi, P. Beck, N. Biver, L. Bonal, J.-Ph. Combe, D. Despan, E. Flamini, S. Fornasier, A. Frigeri, D. Grassi, M. Gudipati, A. Longobardo, K. Markus, F. Merlin, R. Orosei, G. Rinaldi, K. Stephan, M. Cartacci, A. Cicchetti, S. Giuppi, Y. Hello, F. Henry, S. Jacquinod, R. Noschese, G. Peter, R. Politi, J. M. Reess, and A. Semery

Published
2015
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4. Seasonal exposure of carbon dioxide ice on the nucleus of comet 67P/Churyumov-Gerasimenko

Author

Luigi Colangeli, Vito Mennella, Federico Tosi, M. Combes, D. Despan, Patrick G. J. Irwin, Andrea Cicchetti, Lydie Bonal, Bernard Schmitt, Nicolas Biver, M. Cartacci, Florence Henry, Th. Encrenaz, Romolo Politi, Michelangelo Formisano, M. A. Barucci, David Kappel, Eric Quirico, Mauro Ciarniello, Roberto Orosei, Ralf Jaumann, Andrea Longobardo, Katrin Stephan, E. Kuehrt, Fabrizio Capaccioni, Yves Langevin, Wing-Huen Ip, Gianrico Filacchione, Michael R. Combi, Gabriele Arnold, Ernesto Palomba, Giovanna Rinaldi, D. Tiphene, Y. Hello, Robert W. Carlson, Ulrich Schade, Gianfranco Magni, Alessandra Migliorini, G. P. Tozzi, Sonia Fornasier, J. Crovisier, Andrea Raponi, Pierre Beck, U. Fink, Pierre Drossart, Stefano Mottola, Enrico Flamini, M. C. De Sanctis, D. Bockelee-Morvan, Marcello Fulchignoni, Kathrin Markus, Giancarlo Bellucci, M. T. Capria, G. Peter, Davide Grassi, F. Merlin, Sergio Fonti, Costanzo Federico, Eleonora Ammannito, M. I. Blecka, Armando Blanco, Raffaella Noschese, Jean-Michel Reess, T. B. McCord, Alessandro Frigeri, C. Leyrat, Giuseppe Piccioni, Priscilla Cerroni, U. Carsenty, F. Mancarella, L. Moroz, Fredric W. Taylor, Jean-Pierre Bibring, Stéphane Erard, Johannes Benkhoff, S. Jacquinod, J. Ph. Combe, M. S. Gudipati, Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Istituto Nazionale di Astrofisica (INAF), Istituto di Astrofisica Spaziale e Fisica cosmica - Roma (IASF-Roma), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), 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 Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Istituto di Fisica dello Spazio Interplanetario (IFSI), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA), Polska Akademia Nauk = Polish Academy of Sciences (PAN), German Aerospace Center (DLR), INAF - Osservatorio Astronomico di Capodimonte (OAC), Department of Physics [Imperial College London], Imperial College London, Instituto de Estudos Avançados (IEAV), Institut, Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Dipartimento di Fisica, Università degli studi di Lecce, Institute of Space Science [Taiwan], National Central University [Taiwan] (NCU), Department of Physics [Oxford], University of Oxford, Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Department of Earth and Space Sciences [Seattle], University of Washington [Seattle], INAF - Osservatorio Astrofisico di Arcetri (OAA), Laboratoire de Sciences de la Terre, Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Alenia Aerospazio, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Department of Physics [Lecce], Università del Salento [Lecce], JDS Uniphase/Cronos, USA, JDS Uniphase/Cronos, IASI (IASI), Istituti di Ricovero e Cura a Carattere Scientifico (IRCCS), Consiglio Nazionale delle Ricerche (CNR), European Space Agency (ESA), University of Oxford [Oxford], Max-Planck-Institut für Sonnensystemforschung (MPS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), ITA, USA, GBR, FRA, DEU, TWN, and NLD

Subjects
[PHYS]Physics [physics], Multidisciplinary, 010504 meteorology & atmospheric sciences, Infrared, Atmospheric sciences, 01 natural sciences, Astrobiology, chemistry.chemical_compound, medicine.anatomical_structure, chemistry, 13. Climate action, Comet nucleus, Rosetta, 0103 physical sciences, Carbon dioxide, medicine, Environmental science, Surface layer, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Nucleus, Volatility (chemistry), ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

Rosetta observes sublimating surface icesComets are “dirty snowballs” made of ice and dust, but they are dark because the ice sublimates away, leaving some of the dust behind on the surface. The Rosetta spacecraft has provided a close-up view of the comet 67P/Churyumov-Gerasimenko as it passes through its closest point to the Sun (see the Perspective by Dello Russo). Filacchioneet al.detected the spectral signature of solid CO2(dry ice) in small patches on the surface of the nucleus as they emerged from local winter. By modeling how the CO2sublimates, they constrain the composition of comets and how ices generate the gaseous coma and tail. Fornasieret al.studied images of the comet and discovered bright patches on the surface where ice was exposed, which disappeared as the ice sublimated. They also saw frost emerging from receding shadows. The surface of the comet was noticeably less red just after local dawn, indicating that icy material is removed by sunlight during the local day.Science, this issue p.1563, p.1566; see also p.1536

Published
2016
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5. Present and Future Cometary Science with the IRAM Plateau de Bure Interferometer

Author

J. Crovisier, N. Biver, Emmanuel Lellouch, Dominique Bockelée-Morvan, R. Moreno, Jérémie Boissier, R. Neri, Institut de RadioAstronomie Millimétrique (IRAM), Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), 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 Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
Physics, geography, Plateau, geography.geographical_feature_category, Comet, Continuum (design consultancy), Northern Hemisphere, Plateau de Bure Interferometer, Astronomy, Astronomy and Astrophysics, Outgassing, Interferometry, Planetary science, Space and Planetary Science, Earth and Planetary Sciences (miscellaneous), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience; Interferometric observations are essential to probe the molecular emission in the inner cometary atmospheres and study the outgassing from the nucleus. Mapping the continuum emission can provide information about the dust and/or nucleus properties. We present here a summary of the observations of the dust and gas coma of comet 17P/Holmes and nuclear observations of 8P/Tuttle, both carried out with the IRAM interferometer at Plateau de Bure (PdBI) in 2007-2008. The observations of these two comets demonstrate the ability of the PdBI in terms of cometary science. In the near future, several improvements will be made (new receivers at 0.8 mm, a new wide-band correlator) allowing more frequent and more detailed studies of comets. On the long term, NOEMA, an expansion project, may add up to six antennas to the Plateau de Bure Interferometer, and increase the baseline lengths. Such an instrument would offer a complement to ALMA to track comets of the northern hemisphere with about half the sensitivity of ALMA for continuum studies.

Published
2009
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6. Physics and chemistry of comets: recent results from comets Hyakutake and Hale–Bopp Answers to old questions and new enigmas

Author

J. Crovisier

Subjects
Physics, Comet nucleus, Comet dust, Interstellar comet, Comet, Astronomical unit, Astronomy, Physical and Theoretical Chemistry, Astrobiology
Abstract

1996 and 1997 years were very prolific years for cometary studies. In March 1996, C/1996 B2 (Hyakutake), a medium-bright comet, passed at only 0.10 astronomical units (AU) from the Earth. On 1st April, 1997, C/1995 O1 (Hale–Bopp) passed at perihelion. This comet was 10 to 100 times brighter than comet Halley when compared at the same distance. It could be studied and monitored from its discovery in July 1995 as far as 7 AU from the Sun until its perihelion at 0.9 AU, where it was the object of extensive observations. It was thus possible to study these two exceptional comets with modern instrumentation covering the electromagnetic spectrum from radio to X-ray domains. Our knowledge of the composition and nature of comets has been transformed. New cometary molecules were observed, as well as isotopic species. New physical processes could be studied, owing to the large amounts of matter escaping from these objects, to the proximity of Earth allowing a detailed investigation of the region close to the nucleus (comet Hyakutake), or to the unusual physical conditions far from the Sun (comet Hale–Bopp). Selected results of these observations, relevant to the chemistry and physics of molecules and grains, are discussed. It is shown that whereas some old problems are now solved, new ones have emerged. The needs for laboratory data and theoretical work are pointed out.

Published
1998
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