Physical characteristics of G331.5-0.1: The luminous central region of a Giant Molecular Cloud

Abstract

We report molecular line and dust continuum observations toward the high-mass star forming region G331.5-0.1, one of the most luminous regions of massive star-formation in the Milky Way, located at the tangent region of the Norma spiral arm, at a distance of 7.5 kpc. Molecular emission was mapped toward the G331.5-0.1 GMC in the CO (J=1-0) and C18O (J=1-0) lines with NANTEN, while its central region was mapped in CS (J=2-1 and J=5-4) with SEST, and in CS (J=7-6) and 13CO (J=3-2) with ASTE. Continuum emission mapped at 1.2 mm with SIMBA and at 0.87 mm with LABOCA reveal the presence of six compact and luminous dust clumps, making this source one of the most densely populated central regions of a GMC in the Galaxy. The dust clumps are associated with molecular gas and they have the following average properties: size of 1.6 pc, mass of 3.2x10^3 Msun, molecular hydrogen density of 3.7x10^4 cm^{-3}, dust temperature of 32 K, and integrated luminosity of 5.7x10^5 Lsun, consistent with values found toward other massive star forming dust clumps. The CS and 13CO spectra show the presence of two velocity components: a high-velocity component at ~ -89 km s^{-1}, seen toward four of the clumps, and a low-velocity component at ~ -101 km s^{-1} seen toward the other two clumps. Radio continuum emission is present toward four of the molecular clumps, with spectral index estimated for two of them of 0.8+-0.2 and 1.2+-0.2. A high-velocity molecular outflow is found at the center of the brightest clump, with a line width of 26 km s^{-1} (FWHM) in CS (J=7-6). Observations of SiO (J=7-6 and J=8-7), and SO (J_K=8_8-7_7 and J_K=8_7-7_6) lines provide estimates of the gas rotational temperature toward this outflow >120 K and >75 K, respectively.

34 pages, 20 figures, 11 tables, Accepted for Publication in The Astrophysical Journal

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Cited by in corpus (11)

• Giant molecular clouds and massive star formation in the southern milky way
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• The Three-mm Ultimate Mopra Milky Way Survey. II. Cloud and Star Formation Near the Filamentary Ministarburst RCW 106
• Sgr B2(N): A bipolar outflow and rotating hot core revealed by ALMA
• Isocyanic acid (HNCO) in the Hot Molecular Core G331.512-0.103: Observations and Chemical Modelling
• ALMA Observations of the massive molecular outflow G331.512-0.103 II: physical properties, kinematics, and geometry modeling
• Cyanoacetylene in the outflow/hot molecular core G331.512-0.103
• G331.512-0.103: An Interstellar Laboratory for Molecular Synthesis I. The Ortho-to-para Ratios for CH${}_3$OH and CH${}_3$CN
• SiO Outflows in the Most Luminous and Massive Protostellar Sources of the Southern Sky
• A spectral survey of CH3CCH in the Hot Molecular Core G331.512-0.103
• Surveying the Giant HII Regions of the Milky Way with SOFIA: IV. Sgr D, W42, and a Reassessment of the Giant HII Region Census