The physical properties of the dust in the RCW 120 HII region as seen by Herschel

L. D. Anderson (1) , Annie Zavagno (1, 2) , J. A. Rodon , D. Russeil (1) , A. Abergel (3) , P. Ade , P. Andre (4) , H. Arab , J. -P. Baluteau (1) , J. -P. Bernard , K. Blagrave , F. Boulanger (3) , M. Cohen , M. Compiegne , P. Cox , E. Dartois (3) , G. Davis (5) , R. Emery , T. Fulton , C. Gry (1) , E. Habart (3) , M. Huang (6) , C. Joblin (7) , S. C. Jones , J. Kirk (8) , Guilaine Lagache (3) , T. Lim (9) , S. Madden (10) , G. Makiwa , P. Martin (11) , M. -A. Miville-Deschenes (3) , S. Molinari (12) , H. Moseley , F. Motte (13, 14) , D. A. Naylor , K. Okumura , D. Pinheiro Gocalvez , E. Polehampton , P. Saraceno (12) , S. Sidher , L. Spencer , B. Swinyard , D. Ward-Thompson (8) , G. J. White (15) , Sylvain Bontemps (16, 17, 18, 19)

1 LAM - Laboratoire d'Astrophysique de Marseille
2 OAMP - Observatoire Astronomique de Marseille Provence
3 IAS - Institut d'astrophysique spatiale
4 LINA - Laboratoire d'Informatique de Nantes Atlantique
5 Department of Ecology and Evolutionary Biology [Princeton]
6 NAOC - National Astronomical Observatories [Beijing]
7 CESR - Centre d'étude spatiale des rayonnements
8 School of Physics and Astronomy [Cardiff]
9 LPMA - Laboratoire de Probabilités et Modèles Aléatoires
10 DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
11 CITA
12 IFSI - Istituto di Fisica dello Spazio Interplanetario
13 AIM (UMR7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation
14 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
15 Engineering Department
16 LAB - Laboratoire d'Astrophysique de Bordeaux [Pessac]
17 OASU - Observatoire aquitain des sciences de l'univers
18 UB - Université Sciences et Technologies - Bordeaux 1
19 L3AB - Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux

Context. RCW 120 is a well-studied, nearby Galactic HII region with ongoing star formation in its surroundings. Previous work has shown that it displays a bubble morphology at mid-infrared wavelengths and has a massive layer of collected neutral material seen at sub-mm wavelengths. Given the well-defined photo-dissociation region (PDR) boundary and collected layer, it is an excellent laboratory to study the "collect and collapse" process of triggered star formation. Using Herschel Space Observatory data at 100, 160, 250, 350, and 500 micron, in combination with Spitzer and APEX-LABOCA data, we can for the first time map the entire spectral energy distribution of an HII region at high angular resolution. Aims. We seek a better understanding of RCW120 and its local environment by analysing its dust temperature distribution. Additionally, we wish to understand how the dust emissivity index, beta, is related to the dust temperature. Methods. We determine dust temperatures in selected regions of the RCW 120 field by fitting their spectral energy distribution (SED), derived using aperture photometry. Additionally, we fit the SED extracted from a grid of positions to create a temperature map. Results. We find a gradient in dust temperature, ranging from >30 K in the interior of RCW 120, to ~20K for the material collected in the PDR, to ~10K toward local infrared dark clouds and cold filaments. Our results suggest that RCW 120 is in the process of destroying the PDR delineating its bubble morphology. The leaked radiation from its interior may influence the creation of the next generation of stars. We find support for an anti-correlation between the fitted temperature and beta, in rough agreement with what has been found previously. The extended wavelength coverage of the Herschel data greatly increases the reliability of this result.

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

L. D. Anderson, Annie Zavagno, J. A. Rodon, D. Russeil, A. Abergel, et al.. The physical properties of the dust in the RCW 120 HII region as seen by Herschel. Astronomy and Astrophysics - A&A, 2010, 518, pp.L99. ⟨10.1051/0004-6361/201014657⟩. ⟨hal-00523445⟩