2009/12/09 by M. E. Ortega, S. Paron, S. Cichowolski +3
Physics and Astronomy · #Angular resolution (graph drawing) #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Infrared #Ionization #Molecular cloud #Outflow #Star (game theory) #Star formation #Stellar, planetary, and galactic studies #Telescope #Young stellar object #astro-ph.GA
paper · pdf · doi:10.1051/0004-6361/200912722
14 pages, accepted for publication in A&A. Figures degraded to reduce file size
arxiv created 2009/12/09 · openalex publication_date 2009/12/11 · arxiv updated 2015/05/14 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
<i>Aims. <i/>This work aims at investigating the molecular and infrared components in the massive young stellar object (MYSO) candidate IRAS 18544+0112. The purpose is to determine the nature and the origin of this infrared source.<i>Methods. <i/>To analyze the molecular gas towards IRAS 18544+0112, we have carried out observations in a 90 90 region around <i>l<i/> = 3469, <i>b<i/> = -065, using the Atacama Submillimeter Telescope Experiment (ASTE) in the <sup>12<sup/>CO <i>J<i/> = 3–2, <sup>13<sup/>CO <i>J<i/> = 3–2, HCO<sup>+<sup/> <i>J<i/> = 4–3 and CS <i>J<i/> = 7–6 lines with an angular resolution of 22. The infrared emission in the area has been analyzed using 2MASS and Spitzer public data.<i>Results. <i/>From the molecular analysis, we find self-absorbed <sup>12<sup/>CO <i>J<i/> = 3–2 profiles, which are typical in star forming regions, but we do not find any evidence of outflow activity. Moreover, we do not detect either HCO<sup>+<sup/> <i>J<i/> = 4–3 or CS <i>J<i/> = 7–6 in the region, which are species normally enhanced in molecular outflows and high density envelopes. The <sup>12<sup/>CO <i>J<i/> = 3–2 emission profile suggests the presence of expanding gas in the region. The Spitzer images reveal that the infrared source has a conspicuous extended emission bright at 8 <i>μ<i/>m with an evident shell-like morphology of ~15 in size (~1.4 pc at the proposed distance of 3 kpc) that encircles the 24 <i>μ<i/>m emission. The non-detection of ionized gas related to IRAS 18544+0112 together with the fact that it is still embedded in a molecular clump suggest that IRAS 18544+0112 has not reached the UCHII region stage yet. Based on near infrared photometry we search for YSO candidates in the region and propose that 2MASS 18565878+0116233 is the infrared point source associated with IRAS 18544+0112. Finally, we suggest that the expansion of a larger nearby HII region, G034.8-0.7, might be related to the formation of IRAS 18544+0112.