Clouds, filaments and protostars: the Herschel Hi-GAL Milky Way

S. Molinari (1) , B. Swinyard , J. Bally , M. Barlow , J. P. Bernard (2, 3) , P. Martin (4) , T. Moore , A. Noriega-Crespo , R. Plume , L. Testi (5) , Annie Zavagno (6, 7) , A. Abergel (3) , B. Ali , L. Anderson (8) , P. André (9) , J. P. Baluteau , C. Battersby , M. T. Beltrán , M. Benedettini (10) , N. Billot , J. Blommaert , Sylvain Bontemps (11) , F. Boulanger (3) , J. Brand , C. Brunt , M. Burton , L. Calzoletti , S. Carey , P. Caselli (12) , R. Cesaroni (12) , J. Cernicharo (13) , S. Chakrabarti (14) , A. Chrysostomou , M. Cohen , M. Compiegne , P. de Bernardis , G. de Gasperis , A. M. Di Giorgio , D. Elia , F. Faustini , N. Flagey , Y. Fukui , G. A. Fuller , K. Ganga (15) , P. Garcia-Lario (16, 17) , J. Glenn , P. F. Goldsmith , M. J. Griffin , M. Hoare , M. Huang (18) , D. Ikhenaode , C. Joblin (2) , G. Joncas , M. Juvela , J. M. Kirk , Guilaine Lagache (3) , J. Z. Li (18) , T. L. Lim (19) , S. D. Lord , M. Marengo , D. J. Marshall (20) , S. Masi (21) , F. Massi , M. Matsuura (22) , V. Minier (14, 23) , M. A. Miville-Deschenes (3) , L. A. Montier , L. Morgan (24) , F. Motte (14, 23) , J. C. Mottram , T. G. Mueller , P. Natoli (21) , J. Neves , L. Olmi (25) , R. Paladini (2) , D. Paradis , H. Parsons , N. Peretto (23) , M. Pestalozzi , S. Pezzuto (1) , F. Piacentini (21) , L. Piazzo , D. Polychroni , M. Pomarès (7) , C. C. Popescu , W. T. Reach , I. Ristorcelli (2) , J. F. Robitaille , T. Robitaille , J. A. Rodón , A. Roy (26) , P. Royer (27) , D. Russeil (6) , P. Saraceno (1) , M. Sauvage (23) , P. Schilke (28) , E. Schisano , N. Schneider (23) , F. Schuller (28) , B. Schulz (29) , B. Sibthorpe (30) , H. A. Smith , M. D. Smith (31) , L. Spinoglio (25) , D. Stamatellos , F. Strafella , G. S. Stringfellow , E. Sturm , R. Taylor , M. A. Thompson , A. Traficante , R. J. Tuffs , G. Umana , L. Valenziano (25) , R. Vavrek , M. Veneziani (32, 21) , S. Viti (10) , C. Waelkens , D. Ward-Thompson (33) , G. White (19) , L. A. Wilcock , F. Wyrowski (28) , H. W. Yorke , Q. Zhang (34)

1 IFSI - Istituto di Fisica dello Spazio Interplanetario
2 CESR - Centre d'étude spatiale des rayonnements
3 IAS - Institut d'astrophysique spatiale
4 CITA
5 ESO - European Southern Observatory
6 LAM - Laboratoire d'Astrophysique de Marseille
7 OAMP - Observatoire Astronomique de Marseille Provence
8 LABORATORY OF COMPARATIVE CARCINOGENESIS - Laboratory of Comparative Carcinogenesis
9 LINA - Laboratoire d'Informatique de Nantes Atlantique
10 LAOG - Laboratoire d'Astrophysique de Grenoble
11 FORMATION STELLAIRE 2010
12 OAA - INAF - Osservatorio Astrofisico di Arcetri
13 CSIC - Centro de Investigaciones Biológicas
14 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
15 APC - Cosmologie
16 ESA - Espagne - ISO Data Centre
17 ESA Espagne - Herschel Science Centre
18 NAOC - National Astronomical Observatories [Beijing]
19 RAL - STFC Rutherford Appleton Laboratory
20 Universiti Brunei Darussalam
21 Università degli Studi di Roma Tor Vergata [Roma] = University of Rome Tor Vergata
22 University of Manchester [Manchester]
23 AIM (UMR7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation
24 Tenovus Centre for Cancer Research
25 ARENA - Antarctic Research a European Network for Astrophysics
26 Inter University Accelerator Centre
27 LEOSPHERE France
28 MPIFR - Max-Planck-Institut für Radioastronomie
29 LRA - Laboratoire de Radioastronomie
30 ROE - Royal Observatory Edinburgh
31 Atmospheric Sciences Division [Hampton]
32 APC (UMR_7164) - AstroParticule et Cosmologie
33 School of Physics and Astronomy [Cardiff]
34 Shanghai Inst Opt & Fine Mech

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.

Domaines: Astrophysique stellaire et solaire [astro-ph.SR]; Astrophysique stellaire et solaire [astro-ph.SR]

S. Molinari, B. Swinyard, J. Bally, M. Barlow, J. P. Bernard, et al.. Clouds, filaments and protostars: the Herschel Hi-GAL Milky Way. Astronomy and Astrophysics - A&A, 2010, 518, pp.L100. ⟨10.1051/0004-6361/201014659⟩. ⟨hal-00523128⟩