EDP Sciences
Free Access
Volume 446, Number 1, January IV 2006
Page(s) 171 - 184
Section Interstellar and circumstellar matter
DOI https://doi.org/10.1051/0004-6361:20053952
Published online 09 January 2006

A&A 446, 171-184 (2006)
DOI: 10.1051/0004-6361:20053952

Triggered massive-star formation on the borders of Galactic H II regions

II. Evidence for the collect and collapse process around RCW 79
A. Zavagno1, L. Deharveng1, F. Comerón2, J. Brand3, F. Massi4, J. Caplan1 and D. Russeil1

1  Laboratoire d'Astrophysique de Marseille, 2 place Le Verrier, 13248 Marseille Cedex 4, France
    e-mail: annie.zavagno@oamp.fr
2  European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
3  INAF-Istituto di Radioastronomia, via Gobetti 101, 40129 Bologna, Italy
4  INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi, 5, 50125 Firenze, Italy

(Received 30 July 2005 / Accepted 7 September 2005 )

We present SEST-SIMBA 1.2-mm continuum maps and ESO-NTT SOFI $JHK_{\rm S}$ images of the Galactic H II region RCW 79. The millimetre continuum data reveal the presence of massive fragments located in a dust emission ring surrounding the ionized gas. The two most massive fragments are diametrically opposite each other in the ring. The near-IR data, centred on the compact H II region located at the south-eastern border of RCW 79, show the presence of an IR-bright cluster containing massive stars along with young stellar objects with near-IR excesses. A bright near- and mid-IR source is detected towards maser emissions, 1.2 pc north-east of the compact H II region centre. Additional information extracted from the Spitzer GLIMPSE survey is used to discuss the nature of the bright IR sources observed towards RCW 79. Twelve luminous Class I sources are identified towards the most massive millimetre fragments. All these facts strongly indicate that the massive-star formation observed at the border of the H II region RCW 79 has been triggered by its expansion, most probably by the collect and collapse process.

Key words: stars: formation -- stars: pre-main sequence -- ISM: H II regions -- ISM: individual objects: RCW 79

SIMBAD Objects

© ESO 2006

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