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14 results on '"Polychroni, D."'

1. The GAPS program at TNG XLVII: The unusual formation history of V1298 Tau

Author

Turrini, D., Marzari, F., Polychroni, D., Claudi, R., Desidera, S., Mesa, D., Pinamonti, M., Sozzetti, A., Mascareño, A. Suárez, Damasso, M., Benatti, S., Malavolta, L., Micela, G., Zinzi, A., Béjar, V. J. S., Biazzo, K., Bignamini, A., Bonavita, M., Borsa, F., del Burgo, C., Chauvin, G., Delorme, P., Hernández, J. I. González, Gratton, R., Hagelberg, J., Janson, M., Langlois, M., Lanza, A. F., Lazzoni, C., Lodieu, N., Maggio, A., Mancini, L., Molinari, E., Molinaro, M., Murgas, F., and Nardiello, D.

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), Astrophysics - Solar and Stellar Astrophysics, FOS: Physical sciences, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics - Earth and Planetary Astrophysics
Abstract

Observational data from space and ground-based campaigns reveal that the 10-30 Ma old V1298 Tau star hosts a compact and massive system of four planets. Mass estimates for the two outer giant planets point to unexpectedly high densities for their young ages. We investigate the formation of these two outermost giant planets, V1298 Tau b and e, and the present dynamical state of V1298 Tau's global architecture to shed light on the history of this young and peculiar extrasolar system. We perform detailed N-body simulations to explore the link between the densities of V1298 Tau b and e and their migration and accretion of planetesimals within the native circumstellar disk. We combine N-body simulations and the normalized angular momentum deficit (NAMD) analysis to characterize V1298 Tau's dynamical state and connect it to the formation history of the system. We search for outer planetary companions to constrain V1298 Tau's architecture and the extension of its primordial circumstellar disk. The high densities of V1298 Tau b and e suggest they formed quite distant from their host star, likely beyond the CO$_2$ snowline. The higher nominal density of V1298 Tau e suggests it formed farther out than V1298 Tau b. The current architecture of V1298 Tau is not characterized by resonant chains. Planet-planet scattering with an outer giant planet is the most likely cause for the instability, but our search for outer companions using SPHERE and GAIA observations excludes only the presence of planets more massive than 2 M$_\textrm{J}$. The most plausible scenario for V1298 Tau's formation is that the system is formed by convergent migration and resonant trapping of planets born in a compact and plausibly massive disk. The migration of V1298 Tau b and e leaves in its wake a dynamically excited protoplanetary disk and creates the conditions for the resonant chain breaking by planet-planet scattering., Comment: 19 pages, 11 figures, 5 tables. Accepted for publication on Astronomy and Astrophysics

Published
2023
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5. The Switch for High-Mass Star Formation : A Herschel-based model for the origin of OB stars

Author

Rivera Ingraham, Alana, Marston, A., Polychroni, D., and Martin, P.

Subjects
Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

The Herschel Archive covers regions in a wide range of physical and star-forming conditions across the Galaxy with unprecedented sensitivity. Here we introduce the latests results from an ongoing large-scale project focused on investigating and characterising star formation in the most extreme conditions. In particular, we will present new evidence that suggests that high-mass star formation is initiated under very specific threshold conditions, distinguishing it from low-mass star formation. This evidence will be summarised and discussed in context with theoretical models and simulations.

Published
2017
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6. Properties of Hi-GAL clumps in the inner Galaxy]{The Hi-GAL compact source catalogue. I. The physical properties of the clumps in the inner Galaxy ($-71.0^{\circ}< \ell < 67.0^{\circ}$)

Author

Elia, D., Molinari, S., Schisano, E., Pestalozzi, M., Pezzuto, S., Merello, M., Noriega-Crespo, A., Moore, T. J. T., Russeil, D., Mottram, J. C., Paladini, R., Strafella, F., Benedettini, M., Bernard, J. P., Di Giorgio, A., Eden, D. J., Fukui, Y., Plume, R., Bally, J., Martin, P. G., Ragan, S. E., Jaffa, S. E., Motte, F., Olmi, L., Schneider, N., Testi, L., Wyrowski, F., Zavagno, A., Calzoletti, L., Faustini, F., Natoli, P., Palmerim, P., Piacentini, F., Piazzo, L., Pilbratt, G. L., Polychroni, D., Baldeschi, A., Beltr��n, M. T., Billot, N., Cambr��sy, L., Cesaroni, R., Garc��a-Lario, P., Hoare, M. G., Huang, M., Joncas, G., Liu, S. J., Maiolo, B. M. T., Marsh, K. A., Maruccia, Y., M��ge, P., Peretto, N., Rygl, K. L. J., Schilke, P., Thompson, M. A., Traficante, A., Umana, G., Veneziani, M., Ward-Thompson, D., Whitworth, A. P., Arab, H., Bandieramonte, M., Becciani, U., Brescia, M., Buemi, C., Bufano, F., Butora, R., Cavuoti, S., Costa, A., Fiorellino, E., Hajnal, A., Hayakawa, T., Kacsuk, P., Leto, P., Causi, G. Li, Marchili, N., Martinavarro-Armengol, S., Mercurio, A., Molinaro, M., Riccio, G., Sano, H., Sciacca, E., Tachihara, K., Torii, K., Trigilio, C., Vitello, F., and Yamamoto, H.

Subjects
Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

Hi-GAL is a large-scale survey of the Galactic plane, performed with Herschel in five infrared continuum bands between 70 and 500 $��$m. We present a band-merged catalogue of spatially matched sources and their properties derived from fits to the spectral energy distributions (SEDs) and heliocentric distances, based on the photometric catalogs presented in Molinari et al. (2016a), covering the portion of Galactic plane $-71.0^{\circ}< \ell < 67.0^{\circ}$. The band-merged catalogue contains 100922 sources with a regular SED, 24584 of which show a 70 $��$m counterpart and are thus considered proto-stellar, while the remainder are considered starless. Thanks to this huge number of sources, we are able to carry out a preliminary analysis of early stages of star formation, identifying the conditions that characterise different evolutionary phases on a statistically significant basis. We calculate surface densities to investigate the gravitational stability of clumps and their potential to form massive stars. We also explore evolutionary status metrics such as the dust temperature, luminosity and bolometric temperature, finding that these are higher in proto-stellar sources compared to pre-stellar ones. The surface density of sources follows an increasing trend as they evolve from pre-stellar to proto-stellar, but then it is found to decrease again in the majority of the most evolved clumps. Finally, we study the physical parameters of sources with respect to Galactic longitude and the association with spiral arms, finding only minor or no differences between the average evolutionary status of sources in the fourth and first Galactic quadrants, or between "on-arm" and "inter-arm" positions., Accepted by MNRAS

Published
2017
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7. Hi-GAL, the Herschel infrared Galactic Plane Survey: photometric maps and compact source catalogues. First data release for Inner Milky Way: +68��> l > -70��

Author

Molinari, S., Schisano, E., Elia, D., Pestalozzi, M., Traficante, A., Pezzuto, S., Swinyard, B. M., Noriega-Crespo, A., Bally, J., Moore, T. J. T., Plume, R., Zavagno, A., di Giorgio, A. M., Liu, S. J., Pilbratt, G. L., Mottram, J. C., Russeil, D., Piazzo, L., Veneziani, M., Benedettini, M., Calzoletti, L., Faustini, F., Natoli, P., Piacentini, F., Merello, M., Palmese, A., Del Grande, R., Polychroni, D., Rygl, K. L. J., Polenta, G., Barlow, M. J., Bernard, J. -P., Martin, P. G., Testi, L., Ali, B., Andr��, P., Beltr��n, M. T., Billot, N., Brunt, C., Carey, S., Cesaroni, R., Compi��gne, M., Eden, D., Fukui, Y., Garcia-Lario, P., Hoare, M. G., Huang, M., Joncas, G., Lim, T. L., Lord, S. D., Martinavarro-Armengol, S., Motte, F., Paladini, R., Paradis, D., Peretto, N., Robitaille, T., Schilke, P., Schneider, N., Schulz, B., Sibthorpe, B., Strafella, F., Thompson, M. A., Umana, G., Ward-Thompson, D., and Wyrowski, F.

Subjects
Astrophysics of Galaxies (astro-ph.GA), FOS: Physical sciences
Abstract

(Abridged) We present the first public release of high-quality data products (DR1) from Hi-GAL, the {\em Herschel} infrared Galactic Plane Survey. Hi-GAL is the keystone of a suite of continuum Galactic Plane surveys from the near-IR to the radio, and covers five wavebands at 70, 160, 250, 350 and 500 micron, encompassing the peak of the spectral energy distribution of cold dust for 8 < T < 50K. This first Hi-GAL data release covers the inner Milky Way in the longitude range 68�� > l > -70�� in a |b, Astronomy & Astrophysics, accepted

Published
2016
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8. CHIMPS: the CO/C O ( = 3 → 2) Heterodyne Inner Milky Way Plane Survey

Author

Rigby, A. J., Moore, T. J. T., Plume, R., Eden, D. J., Urquhart, J. S., Thompson, M. A., Mottram, J. C., Brunt, C. M., Butner, H. M., Dempsey, J. T., Gibson, S. J., Hatchell, J., Jenness, T., Kuno, N., Longmore, S. N., Morgan, L. K., Polychroni, D., Thomas, H., White, G. J., and Zhu, M.

Subjects
Physics, 010308 nuclear & particles physics, Star formation, Infrared, Milky Way, Resolution (electron density), Astronomy, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Galactic plane, 01 natural sciences, Spectral line, Space and Planetary Science, 0103 physical sciences, Angular resolution, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, James Clerk Maxwell Telescope
Abstract

We present the 13CO/C18O (J = 3 → 2) Heterodyne Inner Milky Way Plane Survey (CHIMPS) which has been carried out using the Heterodyne Array Receiver Program on the 15 m James Clerk Maxwell Telescope (JCMT) in Hawaii. The high-resolution spectral survey currently covers |b| ≤ 0$ $_{.}^{\circ}$$5 and 28deg≲l≲46deg 28deg≲l≲46deg , with an angular resolution of 15 arcsec in 0.5 km s−1 velocity channels. The spectra have a median rms of ∼0.6 K at this resolution, and for optically thin gas at an excitation temperature of 10 K, this sensitivity corresponds to column densities of NH2 ∼ 3 × 1020 cm−2 and NH2 ∼ 4 × 1021 cm−2 for 13CO and C18O, respectively. The molecular gas that CHIMPS traces is at higher column densities and is also more optically thin than in other publicly available CO surveys due to its rarer isotopologues, and thus more representative of the three-dimensional structure of the clouds. The critical density of the J = 3 → 2 transition of CO is ≳104 cm−3 at temperatures of ≤20 K, and so the higher density gas associated with star formation is well traced. These data complement other existing Galactic plane surveys, especially the JCMT Galactic Plane Survey which has similar spatial resolution and column density sensitivity, and the Herschel infrared Galactic Plane Survey. In this paper, we discuss the observations, data reduction and characteristics of the survey, presenting integrated-emission maps for the region covered. Position–velocity diagrams allow comparison with Galactic structure models of the Milky Way, and while we find good agreement with a particular four-arm model, there are some significant deviations.

Published
2015
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9. CHIMPS: the $^{13}$CO/C$^{18}$O (J=3-2) Heterodyne Inner Milky Way Plane Survey

Author

Rigby, AJ, Moore, TJT, Plume, R, Eden, DJ, Urquhart, JS, Thompson, MA, Mottram, JC, Brunt, CM, Butner, HM, Dempsey, JT, Gibson, SJ, Hatchell, J, Jenness, T, Kuno, N, Longmore, SN, Morgan, LK, Polychroni, D, Thomas, H, White, GJ, and Zhu, M

Subjects
Astrophysics of Galaxies (astro-ph.GA), FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, Astrophysics::Galaxy Astrophysics, QB
Abstract

We present the $^{13}$CO/C$^{18}$O (J=3-2) Heterodyne Inner Milky Way Plane Survey (CHIMPS) which has been carried out using the Heterodyne Array Receiver Program on the 15 m James Clerk Maxwell Telescope (JCMT) in Hawaii. The high-resolution spectral survey currently covers |b| < 0.5 deg and 28 < l < 46 deg, with an angular resolution of 15 arcsec in 0.5 km/s velocity channels. The spectra have a median rms of $\sim$ 0.6 K at this resolution, and for optically thin gas at an excitation temperature of 10 K, this sensitivity corresponds to column densities of $N_{\mathrm{H}_{2}} \sim 3 \times 10^{20}\,$cm$^{-2}$ and $N_{\mathrm{H}_{2}} \sim 4 \times 10^{21}\,$cm$^{-2}$ for $^{13}$CO and C$^{18}$O, respectively. The molecular gas that CHIMPS traces is at higher column densities and is also more optically thin than in other publicly available CO surveys due to its rarer isotopologues, and thus more representative of the three-dimensional structure of the clouds. The critical density of the J=3-2 transition of CO is $\gtrsim 10^{4}$ cm$^{-3}$ at temperatures of $\leq 20$ K, and so the higher density gas associated with star formation is well traced. These data complement other existing Galactic plane surveys, especially the JCMT Galactic Plane Survey which has similar spatial resolution and column density sensitivity, and the Herschel infrared Galactic Plane Survey. In this paper, we discuss the observations, data reduction and characteristics of the survey, presenting integrated emission maps for the region covered. Position-velocity diagrams allow comparison with Galactic structure models of the Milky Way, and while we find good agreement with a particular four arm model, there are some significant deviations., Accepted by MNRAS, 15 pages, 9 figures

Published
2015
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10. The first Hi-GAL observations of the outer Galaxy: a look to star formation in the third Galactic quadrant in the longitude range 216.5 < l < 225.5

Author

Elia, D., Molinari, S., Fukui, Y., Schisano, E., Olmi, L., Veneziani, M., Hayakawa, T., Pestalozzi, M., Schneider, N., Benedettini, M., Di Giorgio, A. M., Ikhenaode, D., Mizuno, A., Onishi, T., Pezzuto, S., Piazzo, L., Polychroni, D., Rygl, K. L. J., Yamamoto, H., and Maruccia, Y.

Subjects
Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

We present the first Herschel PACS and SPIRE photometric observations in a portion of the outer Galaxy ($216.5^{\circ} \lesssim \ell \lesssim 225.5^{\circ}$ and $-2^{\circ} \lesssim b \lesssim 0^{\circ}$) as a part of the Hi-GAL survey. The maps between 70 and 500 $��$m, the derived column density and temperature maps, and the compact source catalog are presented. NANTEN CO(1-0) line observations are used to derive cloud kinematics and distances, so that we can estimate distance-dependent physical parameters of the compact sources (cores and clumps) having a reliable spectral energy distribution, that we separate in 255 proto-stellar and 688 starless. Both typologies are found in association with all the distance components observed in the field, up to $\sim 5.8$ kpc, testifying the presence of star formation beyond the Perseus arm at these longitudes. Selecting the starless gravitationally bound sources we identify 590 pre-stellar candidates. Several sources of both proto- and pre-stellar nature are found to exceed the minimum requirement for being compatible with massive star formation, based on the mass-radius relation. For the pre-stellar sources belonging to the Local arm ($d\lesssim1.5$ kpc) we study the mass function, whose high-mass end shows a power-law $N(\log M) \propto M^{-1.0 \pm 0.2}$. Finally, we use a luminosity vs mass diagram to infer the evolutionary status of the sources, finding that most of the proto-stellar are in the early accretion phase (with some cases compatible with a Class I stage), while for pre-stellar sources, in general, accretion has not started yet., Accepted by ApJ

Published
2013
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11. On the shape of the mass-function of dense clumps in the Hi-GAL fields. I. SED determination and global properties of the mass-functions

Author

Olmi, L., Angles-Alcazar, D., Elia, D., Molinari, S., Montier, L., Pestalozzi, M., Pezzuto, S., Polychroni, D., Ristorcelli, I., Rodon, J., Schisano, E., Smith, M. D., Testi, L., and Thompson, M.

Subjects
Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, Astrophysics::Galaxy Astrophysics
Abstract

Stars form in dense, dusty clumps of molecular clouds, but little is known about their origin and evolution. In particular, the relationship between the mass distribution of these clumps (also known as the "clump mass function", or CMF) and the stellar initial mass function (IMF), is still poorly understood. In order to discern the "true" shape of the CMF and to better understand how the CMF may evolve toward the IMF, large samples of bona-fide pre- and proto-stellar clumps are required. The sensitive observations of the Herschel Space Observatory (HSO) are now allowing us to look at large clump populations in various clouds with different physical conditions. We analyse two fields in the Galactic plane mapped by HSO during its science demonstration phase, as part of the more complete and unbiased Herschel infrared GALactic Plane Survey (Hi-GAL). These fields undergo a source-extraction and flux-estimation pipeline, which allows us to obtain a sample with thousands of clumps. Starless and proto-stellar clumps are separated using both color and positional criteria to find those coincident with MIPS 24 micron sources. We describe the probability density functions of the power-law and lognormal models that are used to fit the CMFs, and we then find their best-fit parameters. For the lognormal model we apply several statistical techniques to the data and compare their results. The CMFs of the two SDP fields show very similar shapes, but very different mass scales. This similarity is confirmed by the values of the best-fit parameters of either the power-law or lognormal model. The power-law model leads to almost identical CMF slopes, whereas the lognormal model shows that the CMFs have similar widths. The similar CMF shape but different mass scale represents an evidence that the overall process of star formation in the two regions is very different., Comment: This article is composed of 14 pages, 5 figures and is based on Hi-GAL data. Submitted for publication to Astronomy & Astrophysics on 19 sept. 2012

Published
2012
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12. VizieR Online Data Catalog: JCMT Plane Survey: l=30° field (Moore+, 2015)

Author

Moore, T. J. T., Plume, R., Thompson, M. A., Parsons, H., Urquhart, J. S., Eden, D. J., Dempsey, J. T., Morgan, L. K., Thomas, H. S., Buckle, J., Brunt, C. M., Butner, H., Carretero, D., Chrysostomou, A., Devilliers, H. M., Fich, M., Hoare, M. G., Manser, G., Mottram, J. C., Natario, C., Olguin, F., Peretto, N., Polychroni, D., Redman, R. O., Rigby, A. J., Salji, C., Summers, L. J., Berry, D., Currie, M. J., Jenness, T., Pestalozzi, M., Traficante, A., Bastien, P., Difrancesco, J., Davis, C. J., Evans, A., Friberg, P., Fuller, G. A., Gibb, A. G., Gibson, S., Hill, T., Doug Johnstone, Joncas, G., Longmore, S. N., Lumsden, S. L., Martin, P. G., Nguyen Luong, Q., Pineda, J. E., Purcell, C., Richer, J. S., Schieven, G. H., Shipman, R., Spaans, M., Taylor, A. R., Viti, S., Weferling, B., White, G. J., and Zhu, M.

13. Clouds, filaments, and protostars: The Herschel Hi-GAL Milky Way

Author

J. A. Rodón, K. Ganga, M. Pomarès, Friedrich Wyrowski, Mika Juvela, F. Piacentini, Melvin Hoare, William T. Reach, Stefano Pezzuto, A. Roy, Jean-Paul Baluteau, Marc-Antoine Miville-Deschenes, Russell H. Taylor, Pierre Royer, Alessio Traficante, Peter Schilke, D. Paradis, Glenn J. White, Cara Battersby, Alberto Noriega-Crespo, Harriet Parsons, M. Veneziani, Dimitrios Stamatellos, Vincent Minier, Lorenzo Piazzo, Guy S. Stringfellow, Michael G. Burton, L. K. Morgan, Frederic Schuller, F. Faustini, P. Saraceno, S. D. Lord, Jason Glenn, E. Sturm, Michael D. Smith, G. Joncas, A. M. di Giorgio, D. Polychroni, L. Montier, D. J. Marshall, N. Billot, José Cernicharo, F. Boulanger, M. T. Beltrán, Paul Martin, Matthew Joseph Griffin, B. Swinyard, Guilaine Lagache, Serena Viti, Mathieu Compiegne, Derek Ward-Thompson, P. de Bernardis, Frédérique Motte, B. Sibthorpe, Sukanya Chakrabarti, Nicolas Flagey, Christopher M. Brunt, Maggie A. Thompson, Qizhou Zhang, J.-P. Bernard, Annie Zavagno, Jean-François Robitaille, L. Spinoglio, Marc Sauvage, D. Russeil, Paolo Natoli, A. Abergel, Babar Ali, Davide Elia, D. Ikhenaode, Gary A. Fuller, C. Joblin, G. de Gasperis, Eugenio Schisano, Pedro García-Lario, Jin-Zeng Li, Isabelle Ristorcelli, Sergio Molinari, Luca Calzoletti, M. R. Pestalozzi, Nicolas Peretto, Thomas P. Robitaille, Mikako Matsuura, Riccardo Cesaroni, Rene Plume, Jan Brand, Paul F. Goldsmith, Leonardo Testi, Joseph C. Mottram, H. W. Yorke, Cristina Popescu, Martin Cohen, M. Benedettini, M. J. Barlow, Antonio Chrysostomou, Paola Caselli, Luca Olmi, Maohai Huang, Massimo Marengo, R. Paladini, Fabrizio Massi, L. A. Wilcock, Grazia Umana, Francesco Strafella, Toby J. T. Moore, Benjamin L. Schulz, R. Vavrek, T. Mueller, John Bally, J. A. D. L. Blommaert, L. D. Anderson, C. Waelkens, T. L. Lim, Richard J. Tuffs, Sean Carey, Yasuo Fukui, J. Neves, Nicola Schneider, Jason M. Kirk, Silvia Masi, Pascal André, Howard A. Smith, Luca Valenziano, Sylvain Bontemps, Istituto di Fisica dello Spazio Interplanetario (IFSI), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), 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), 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), CITA, University of Toronto, European Southern Observatory (ESO), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Observatoire Astronomique de Marseille Provence (OAMP), Université de Provence - Aix-Marseille 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratory of Comparative Carcinogenesis (LABORATORY OF COMPARATIVE CARCINOGENESIS), National Cancer Institute [Bethesda] (NCI-NIH), National Institutes of Health [Bethesda] (NIH)-National Institutes of Health [Bethesda] (NIH), Laboratoire d'Informatique de Nantes Atlantique (LINA), Mines Nantes (Mines Nantes)-Université de Nantes (UN)-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), FORMATION STELLAIRE 2010, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (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)-Université de Bordeaux (UB), INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Centro de Investigaciones Biológicas (CSIC), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, APC - Cosmologie, AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-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)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-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), ISO Data Centre (ESA - Espagne), Agence Spatiale Européenne = European Space Agency (ESA), Herschel Science Centre (ESA Espagne), National Astronomical Observatories [Beijing] (NAOC), Chinese Academy of Sciences [Beijing] (CAS), STFC Rutherford Appleton Laboratory (RAL), Science and Technology Facilities Council (STFC), Universiti Brunei Darussalam, Biology Department, Universitii Brunei Darussalam, Università degli Studi di Roma Tor Vergata [Roma], University of Manchester [Manchester], Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Tenovus Centre for Cancer Research, Welsh School of Pharmacy, Antarctic Research a European Network for Astrophysics (ARENA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Inter University Accelerator Centre, Aruna Asaf Ali Marg, LEOSPHERE France, LEOSPHERE, Max-Planck-Institut für Radioastronomie (MPIFR), Laboratoire de Radioastronomie (LRA), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - 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P., Martin, P., Moore, T., Noriega Crespo, A., Plume, R., Testi, L., Zavagno, A., Abergel, A., Ali, B., Anderson, L., Andre, P., Baluteau, J. P., Battersby, C., Beltrán, M. T., Benedettini, M., Billot, N., Blommaert, J., Bontemps, S., Boulanger, F., Brand, J., Brunt, C., Burton, M., Calzoletti, L., Carey, S., Caselli, P., Cesaroni, R., Cernicharo, J., Chakrabarti, S., Chrysostomou, A., Cohen, M., Compiegne, M., de Bernardis, P., de Gasperis, G., di Giorgio, A. M., Elia, Davide Quintino, Faustini, F., Flagey, N., Fukui, Y., Fuller, G. A., Ganga, K., Garcia Lario, P., Glenn, J., Goldsmith, P. F., Griffin, M., Hoare, M., Huang, M., Ikhenaode, D., Joblin, C., Joncas, G., Juvela, M., Kirk, J. M., Lagache, G., Li, J. Z., Lim, T. L., Lord, S. D., Marengo, M., Marshall, D. J., Masi, S., Massi, F., Matsuura, M., Minier, V., Miville Deschênes, M. A., Montier, L. A., Morgan, L., Motte, F., Mottram, J. C., Müller, T. G., Natoli, P., Neves, J., Olmi, L., Paladini, R., Paradis, D., Parsons, H., Peretto, N., Pestalozzi, M., Pezzuto, S., Piacentini, F., Piazzo, L., Polychroni, D., Pomarès, M., Popescu, C. C., Reach, W. T., Ristorcelli, I., Robitaille, J. F., Robitaille, T., Rodón, J. A., Roy, A., Royer, P., Russeil, D., Saraceno, P., Sauvage, M., Schilke, P., Schisano, E., Schneider, N., Schuller, F., Schulz, B., Sibthorpe, B., Smith, H. A., Smith, M. D., Spinoglio, L., Stamatellos, D., Strafella, Francesco, Stringfellow, G. S., Sturm, E., Taylor, R., Thompson, M. A., Traficante, A., Tuffs, R. J., Umana, G., Valenziano, L., Vavrek, R., Veneziani, M., Viti, S., Waelkens, C., Ward Thompson, D., White, G., Wilcock, L. A., Wyrowski, F., Yorke, H. 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Subjects
010504 meteorology & atmospheric sciences, Field (physics), Milky Way, stars: formation, ISM: structure, ISM: clouds, Galaxy: general, FOS: Physical sciences, ism: structure, ism: clouds, galaxy: general, Astrophysics, 01 natural sciences, Protein filament, Settore FIS/05 - Astronomia e Astrofisica, 0103 physical sciences, Protostar, Infrared dark cloud, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy and Astrophysics, Galactic plane, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astrophysics - Astrophysics of Galaxies, Core (optical fiber), Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Magnetohydrodynamics
Abstract

We present the first results from the science demonstration phase for the Hi-GAL survey, the Herschel key-project that will map the inner Galactic Plane of the Milky Way in 5 bands. We outline our data reduction strategy and present some science highlights on the two observed 2{\deg} x 2{\deg} tiles approximately centered at l=30{\deg} and l=59{\deg}. The two regions are extremely rich in intense and highly structured extended emission which shows a widespread organization in filaments. Source SEDs can be built for hundreds of objects in the two fields, and physical parameters can be extracted, for a good fraction of them where the distance could be estimated. The compact sources (which we will call 'cores' in the following) are found for the most part to be associated with the filaments, and the relationship to the local beam-averaged column density of the filament itself shows that a core seems to appear when a threshold around A_V of about 1 is exceeded for the regions in the l=59{\deg} field; a A_V value between 5 and 10 is found for the l=30{\deg} field, likely due to the relatively larger distances of the sources. This outlines an exciting scenario where diffuse clouds first collapse into filaments, which later fragment to cores where the column density has reached a critical level. In spite of core L/M ratios being well in excess of a few for many sources, we find core surface densities between 0.03 and 0.5 g cm-2. Our results are in good agreement with recent MHD numerical simulations of filaments forming from large-scale converging flows., Comment: A&A, accepted

14. A Herschel study of YSO evolutionary stages and formation timelines in two fields of the Hi-GAL survey

Author

A. Di Giorgio, Stefano Pezzuto, John Bally, Alessio Traficante, M. R. Pestalozzi, Francesco Strafella, F. Piacentini, Sergio Molinari, L. Calzoletti, Mark Thompson, D. Polychroni, Daniel Anglés-Alcázar, E. Schisano, Thomas P. Robitaille, Davide Elia, Joseph C. Mottram, Milena Benedettini, Roberta Paladini, Guy S. Stringfellow, Paul Martin, Michael D. Smith, Jin-Zeng Li, Leonardo Testi, Luca Olmi, Cara Battersby, M. Veneziani, L. K. Morgan, F. Faustini, Paolo Natoli, Nicolas Billot, Frédérique Motte, Elia, Davide Quintino, Schisano, E., Molinari, S., Robitaille, T., Anglés Alcázar, D., Bally, J., Battersby, C., Benedettini, M., Billot, N., Calzoletti, L., di Giorgio, A. M., Faustini, F., Li, J. Z., Martin, P., Morgan, L., Motte, F., Mottram, J. C., Natoli, P., Olmi, L., Paladini, R., Piacentini, F., Pestalozzi, M., Pezzuto, S., Polychroni, D., Smith, M. D., Strafella, Francesco, Stringfellow, G. S., Testi, L., Thompson, M. A., Traficante, A., and Veneziani, M.

Subjects
Physics, stelle di pre-sequenza principale, Field (physics), Infrared, Star formation, FOS: Physical sciences, Astronomy and Astrophysics, stars: formation / stars: pre-main sequence, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Galactic plane, Astrophysics - Astrophysics of Galaxies, formazione stellare, Luminosity, Stars, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Spectral energy distribution, Astrophysics::Solar and Stellar Astrophysics, Main sequence, Astrophysics::Galaxy Astrophysics
Abstract

We present a first study of the star-forming compact dust condensations revealed by Herschel in the two 2 \times 2 \degr Galactic Plane fields centered at [l;b] = [30\degr; 0 \degr] and [l;b] = [59\degr; 0 \degr], respectively, and observed during the Science Demonstration Phase for the Herschel infrared Galactic Plane survey (Hi-GAL) Key-Project. Compact source catalogs extracted for the two fields in the five Hi-GAL bands (70, 160, 250, 350 and 500 $\mu$m) were merged based on simple criteria of positional association and spectral energy distribution (SED) consistency into a final catalog which contains only coherent SEDs with counterparts in at least three adjacent Herschel bands. These final source lists contain 528 entries for the l = 30\degr field, and 444 entries for the l = 59\degr field. The SED coverage has been augmented with ancillary data at 24 $\mu$m and 1.1 mm. SED modeling for the subset of 318 and 101 sources (in the two fields, respectively) for which the distance is known was carried out using both a structured star/disk/envelope radiative transfer model and a simple isothermal grey-body. Global parameters like mass, luminosity, temperature and dust properties have been estimated. The Lbol/Menv ratio spans four orders of magnitudes from values compatible with the pre-protostellar phase to embedded massive zero-age main sequence stars. Sources in the l = 59\degr field have on average lower L/M, possibly outlining an overall earlier evolutionary stage with respect to the sources in the l = 30\degr field. Many of these cores are actively forming high-mass stars, although the estimated core surface densities appear to be an order of magnitude below the 1 g cm$^{-2}$ critical threshold for high-mass star formation., Comment: To appear in A&A

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