A multiwavelength study of the star forming region IRAS 18544+0112

M. E. ORTEGA; S. PARON; S. CICHOWOLSKI; M. RUBIO; G. CASTELLETTI; G. DUBNER

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Año: 2010 vol. 510 p. 1 - 7

0004-6361

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. To analyze the molecular gas towards IRAS~18544+0112, we have carried out observations in a 90´ x 90´  region around l = 34°.69, b =-0°.65, using the Atacama Submillimeter Telescope Experiment (ASTE) in the 12CO J=3-2, 13CO J=3-2, HCO+ J=4-3 and CS J=7-6 lines with an angular resolution of 22´. The infrared emission in the area has been analyzed using 2MASS and Spitzer public data. From the molecular analysis, we find self-absorbed 12CO J=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+ J=4-3 or CS J=7-6 in the region, which are species normally enhanced in molecular outflows and high density envelopes. The 12CO J=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 microns with an evident shell-like morphology of ~ 1.5 arcmin in size (~ 1.4 pc at the proposed distance of 3 kpc) that encircles the 24 $mu$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 proposed 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.