The true nature of the alleged planetary nebula W16-185

Abstract

We report the discovery of a small cluster of massive stars embedded in a NIR nebula in the direction of the IRAS15411-5352 point source, which is related to the alleged planetary nebula W16-185. The majority of the stars present large NIR excess characteristic of young stellar objects and have bright counterparts in the Spitzer IRAC images; the most luminous star (IRS1) is the NIR counterpart of the IRAS source. We found very strong unresolved Brgamma emission at the IRS1 position and more diluted and extended emission across the continuum nebula. From the sizes and electron volume densities we concluded that they represent ultra-compact and compact HII regions, respectively. Comparing the Brgamma emission with the 7 mm free-free emission, we estimated that the visual extinction ranges between 14 and 20 mag. We found that only one star (IRS1) can provide the number of UV photons necessary to ionize the nebula.

arXiv comment30 pages, 15 figures, 2 tables V3: minor grammatical changes. Figure 4 is available in pdf file. Accepted for publication in AJ, April / 2006

References in corpus (4)

• Correcting for the Effects of Interstellar Extinction
• Radio Continuum and Recombination Line Study of UC HII Regions with Extended Envelopes
• Direct Observations of the Ionizing Star in the UC HII Region G29.96-0.02: A Strong Constraint on the Stellar Birth Line for Massive Stars
• Discovery of a young massive stellar cluster associated with IRAS source 16177-5018

Cited by in corpus (5)

• Stellar clusters in the inner Galaxy and their correlation with cold dust emission
• GEMINI near-infrared spectroscopic observations of young massive stars embedded in molecular clouds
• The VVV Near-IR Galaxy Catalogue beyond the Galactic disk
• The young stellar cluster [DBS2003] 157 associated with the H II region GAL 331.31-00.34
• Optical Polarimetric and Near-Infrared Photometric Study of the RCW95 Galactic HII Region