Unveiling the molecular environment of the ring nebula RCW 78

Abstract

We present a study of the ionized, neutral atomic, and molecular gas associated with the ring nebula RCW 78 around the WR star HD 117688 (= WR 55). We based our study on CO observations carried out with the SEST and NANTEN telescopes. We report the detection of molecular gas with velocities in the range -56 to -33 km/s. The CO emission is mainly connected to the western section, with a total molecular mass of 1.3 x 10^5 solar masses. The analysis of the HI gas distribution reveals the HI envelope of the molecular cloud, while the radio continuum emission shows a ring-like structure, which is the radio counterpart of the optical nebula. The gas distribution is compatible with the western section of RCW 78 having originated in the photodissociation and ionization of the molecular gas by HD 117688, and with the action of the stellar winds of the WR star. A number of infrared point sources classified as YSO candidates showed that stellar formation activity is present in the molecular gas linked to the nebula. The fact that the expansion of the bubble have triggered star formation in this region can not be discarded.

15 pages, 11 Postscript figures, to be published in A&A

References in corpus (10)

• Physical Properties of Wolf-Rayet Stars
• A Catalog of Extended Green Objects (EGOs) in the GLIMPSE Survey: A new sample of massive young stellar object outflow candidates
• A census of the Wolf-Rayet content in Westerlund 1 from near-infrared imaging and spectroscopy
• IR Dust Bubbles: Probing the Detailed Structure and Young Massive Stellar Populations of Galactic HII Regions
• Clustered and Triggered Star Formation in W5: Observations with Spitzer
• Triggered massive-star formation on the borders of Galactic HII regions. IV- Star formation at the periphery of Sh2-212
• Spitzer observations of the Massive star forming complex S254-S258: structure and evolution
• The Spitzer Survey of the Small Magellanic Cloud: Discovery of Embedded Protostars in the HII Region NGC 346
• IR Dust Bubbles II: Probing the Detailed Structure and Young Massive Stellar Populations of Galactic HII Regions
• A tale of two cores: Triggered massive star formation in the bright-rimmed cloud SFO 75

Cited by in corpus (9)

• WISE morphological study of Wolf-Rayet nebulae
• The search for magnetic fields in two Wolf-Rayet stars and the discovery of a variable magnetic field in WR55
• The molecular gas around the luminous blue variable star G24.73+0.69
• Star formation activity in the neighbourhood of W-R 1503-160L star in the mid-infrared bubble N46
• 870 micron continuum observations of the bubble-shaped nebula Gum 31
• Molecular gas towards G18.8+1.8
• Molecules, dust, and protostars in NGC 3503
• Star forming regions linked to RCW78 and the discovery of a new IR bubble
• NANTEN 12CO (J=1-0) observations around the star WR 55