skip to main content

SciTech ConnectSciTech Connect

Title: PHYSICAL CHARACTERISTICS OF G331.5-0.1: THE LUMINOUS CENTRAL REGION OF A GIANT MOLECULAR CLOUD

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 {yields} 0) and C{sup 18}O(J = 1 {yields} 0) lines with NANTEN, while its central region was mapped in CS(J = 2 {yields} 1 and J = 5 {yields} 4) with SEST, and in CS(J = 7 {yields} 6) and {sup 13}CO(J = 3 {yields} 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 3.2 Multiplication-Sign 10{sup 3} M{sub Sun }, molecular hydrogen density of 3.7 Multiplication-Sign 10{sup 4} cm{sup -3}, dust temperature of 32 K, and integrated luminosity of 5.7 Multiplication-Sign 10{sup 5} L{sub Sun },more » consistent with values found toward other massive star-forming dust clumps. The CS and {sup 13}CO spectra show the presence of two velocity components: a high-velocity component at {approx} - 89 km s{sup -1}, seen toward four of the clumps, and a low-velocity component at {approx} - 101 km s{sup -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{sup -1} (FWHM) in CS(J = 7 {yields} 6). Observations of SiO(J = 7 {yields} 6 and J = 8 {yields} 7), and SO(J{sub K} = 8{sub 8} {yields} 7{sub 7} and J{sub K} = 8{sub 7} {yields} 7{sub 6}) lines provide estimates of the gas rotational temperature toward this outflow >120 K and >75 K, respectively.« less
Authors:
; ;  [1] ;  [2] ;  [3] ;  [4]
  1. Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile)
  2. Joint ALMA Observatory (JAO), Alonso de Cordova 3107, Vitacura, Santiago (Chile)
  3. University of Texas at Austin, 1 University Station, Austin, TX 78712 (United States)
  4. Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy)
Publication Date:
OSTI Identifier:
22133958
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 774; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON MONOXIDE; COSMIC DUST; DENSITY; HYDROGEN; LINE WIDTHS; LUMINOSITY; MILKY WAY; MOLECULES; SILICON OXIDES; STARS; TEMPERATURE RANGE 0013-0065 K