AMMONIA AND CO OBSERVATIONS TOWARD LOW-LUMINOSITY 6.7 GHz METHANOL MASERS

Journal Article · Wed Sep 01 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/720/1/392· OSTI ID:21460121

Wu, Y W; Xu, Y; Yang, J; Zhang, S B ^[1]; Pandian, J D ^[2]; Henkel, C; Menten, K M ^[3]

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1. Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)
2. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
3. Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany)

To investigate whether distinctions exist between low- and high-luminosity Class II 6.7 GHz methanol masers, we have undertaken multi-line mapping observations of various molecular lines, including the NH{sub 3} (1,1), (2,2), (3,3), (4,4), and {sup 12}CO (1-0) transitions, toward a sample of nine low-luminosity 6.7 GHz masers and {sup 12}CO (1-0) observations toward a sample of eight high-luminosity 6.7 GHz masers, for which we already had NH{sub 3} spectral line data. Emission in the NH{sub 3} (1,1), (2,2), and (3,3) transitions was detected in eight out of nine low-luminosity maser sources, in which 14 cores were identified. We derive densities, column densities, temperatures, core sizes, and masses of both low- and high-luminosity maser regions. A comparative analysis of the physical quantities reveals marked distinctions between the low-luminosity and high-luminosity groups: in general, cores associated with high-luminosity 6.7 GHz masers are larger and more massive than those traced by low-luminosity 6.7 GHz masers; regions traced by the high-luminosity masers have larger column densities but lower densities than those of the low-luminosity maser regions. Further, strong correlations between 6.7 GHz maser luminosity and NH{sub 3} (1,1) and (2,2) line widths are found, indicating that internal motions in high-luminosity maser regions are more energetic than those in low-luminosity maser regions. A {sup 12}CO (1-0) outflow analysis also shows distinctions in that outflows associated with high-luminosity masers have wider line wings and larger sizes than those associated with low-luminosity masers.

• OSTI ID: 21460121
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 720; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ALCOHOLS
AMMONIA
AMPLIFIERS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
ELECTRONIC EQUIPMENT
EQUIPMENT
EVOLUTION
HYDRIDES
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
LINE WIDTHS
LUMINOSITY
MASERS
METHANOL
MICROWAVE AMPLIFIERS
MICROWAVE EQUIPMENT
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
OPTICAL PROPERTIES
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
STAR EVOLUTION
STARS