Molecular gas and star formation towards the IR dust bubble S24 and its environs

N.U. DURONEA; C.H. LÓPEZ-CARBALLO; C. E. CAPPA; J. VASQUEZ; M.M. VAZZANO; V. FIRPO; M. RUBIO

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2016 vol. 585 p. 1 - 17

0004-6361

  {Using the APEX telescope, we mapped the molecular emission in the CO(2-1), $^{13}$CO(2-1),  C$^{18}$O(2-1), and $^{13}$CO(3-2) lines in a region of about $5arcmin imes 5arcmin$ in size around the bubble. The cold dust distribution was analyzed using submillimeter continuum images from ATLASGAL and Herschel. Complementary IR and radio data at different wavelengths were used to complete the study of the interstellar medium in the region.}  % results heading (mandatory)   {The molecular gas distribution shows that gas linked to the S,24 bubble, G341.220-0.213, and G341.217-0.237 has velocities between --48.0 kms and --40.0 kms, compatible with a kinematical distance of 3.7 kpc generally adopted for the region. The gas distribution reveals a shell-like molecular structure of  $sim$0.8 pc in radius bordering the S,24 bubble. A cold dust counterpart of the shell is  detected  in the LABOCA and Herschel-SPIRE images.  The presence of weak extended emission at 24 $mu$m from warm dust  and  radio continuum emission projected inside the bubble indicates the existence of exciting sources and that the bubble is a compact hii region. Part of the molecular gas bordering the S,24 hii region coincides with the extended infrared dust cloud SDC341.194-0.221. A molecular and cold dust clump is present at the interfase between the S,24 hii region and G341.217-0.237, shapping the eastern border of the IR bubble. As regards G341.220-0.213, the presence of an arc-like molecular structure encircling the northern and eastern sections of this IR source indicates that G341.220-0.213 is  interacting with the molecular gas. The analysis of the available IR point source catalogs reveals the existence of young stellar objects (YSO) candidates linked to the IR extended sources, thus confirming its nature as active star-forming regions.  Gas and dust masses were estimated for the different features.The total gas mass in the region and the H$_2$ ambient density amount to 10300 msun and 5900 cmtres, indicating that guno, gdos, and the S,24 hii region are evolving in a high density medium. A triggering star formation scenario for the hii region is investigated.