THE HOT AND CLUMPY MOLECULAR COCOON SURROUNDING THE ULTRACOMPACT H II REGION G5.89-0.39

Journal Article · Sat Oct 10 04:00:00 EDT 2009 · Astrophysical Journal (Online)

DOI:https://doi.org/10.1088/0004-637X/704/1/L5· OSTI ID:21367459

Yunung, Su; Shengyuan, Liu; Kuosong, Wang; Hueiru, Chen ^[1]

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1. Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan (China)

We present observations of CH{sub 3}CN (12-11) emission at a resolution of approx2'' toward the shell-like ultracompact H II region G5.89-0.39 with the Submillimeter Array. The integrated CH{sub 3}CN emission reveals a dense and hot-molecular cocoon in the periphery of the H II region G5.89-0.39, with a CH{sub 3}CN deficient region roughly centered at G5.89-0.39. By analyzing the CH{sub 3}CN emission using population diagram analysis, we find, for the first time, a decreasing temperature structure from 150 K to 40 K with the projected distance from Feldt's star, which is thought to be responsible for powering the H II region. Our results further indicate that the majority of the heating energy in the observed dense gas is supplied by the Feldt's star. From the derived CH{sub 3}CN column density profile, we conclude that the dense gas is not uniformly distributed but centrally concentrated, with a power-law exponent of 5.5 for r approx< 8000 AU, and 2.0 for 8000 AU approx< r approx< 20000 AU, where r is the distance to Feldt's star. The estimated large power index of 5.5 can be attributed to an enhancement of CH{sub 3}CN abundance in the close vicinity of Feldt's star.

• OSTI ID: 21367459
• Journal Information: Astrophysical Journal (Online), Journal Name: Astrophysical Journal (Online) Journal Issue: 1 Vol. 704; ISSN 1538-4357
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
ACETONITRILE
CLOUDS
DENSITY
DISTANCE
EMISSION
NITRILES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHYSICAL PROPERTIES
STARS