OH Survey along Sightlines of Galactic Observations of Terahertz C

	OH Survey along Sightlines of Galactic Observations of Terahertz C
	Tang, Ningyu 1,2; Li, Di1,2,3 ; Heiles, Carl 4; Yue, Nannan 1,2; Dawson, J. R.5,6,7; Goldsmith, Paul F.8; Krco, Marko 1; McClure-Griffiths, N. M.9; Wang, Shen1,2 ; Zuo, Pei 1,2
刊名	ASTROPHYSICAL JOURNAL
	2017-04-10
卷号	839 期号:1
关键词	evolution ISM: clouds ISM: molecules
英文摘要	We have obtained OH spectra of four transitions in the (2)Pi(3/2) ground state, at 1612, 1665, 1667, and 1720 MHz, toward 51 sightlines that were observed in the Herschel project Galactic Observations of Terahertz C+. The observations cover the longitude range of (32 degrees, 64 degrees) and (189 degrees, 207 degrees) in the northern Galactic plane. All of the diffuse OH emissions conform to the so-called "Sum Rule" of the four brightness temperatures, indicating optically thin emission conditions for OH from diffuse clouds in the Galactic plane. The column densities of the H I "halos" N(H-I) surrounding molecular clouds increase monotonically with OH column density, N(OH), until saturating when N(H-I)= 1.0 x 10(21) cm(-2) and N(OH) >= 4.5 x 10(15) cm(-2), indicating the presence of molecular gas that cannot be traced by H I. Such a linear correlation, albeit weak, is suggestive of H (I) halos' contribution to the UV shielding required for molecular formation. About 18% of OH clouds have no associated CO emission (CO-dark) at a sensitivity of 0.07 K, but are associated with C+ emission. A weak correlation exists between C+ intensity and OH column density for CO-dark molecular clouds. These results imply that OH seems to be a better tracer of molecular gas than CO in diffuse molecular regions.
WOS标题词	Science & Technology ; Physical Sciences
类目[WOS]	Astronomy & Astrophysics
研究领域[WOS]	Astronomy & Astrophysics
关键词[WOS]	INTERSTELLAR DUST CLOUDS ; NARROW SELF-ABSORPTION ; DARK MOLECULAR GAS ; WARM NEUTRAL HALOS ; MILKY-WAY ; H-I ; EMISSION ; GALAXY ; HYDROXYL ; CORES
收录类别	SCI
语种	英语
WOS记录号	WOS:000399122600004
内容类型	期刊论文
源URL	[http://ir.bao.ac.cn/handle/114a11/8389]
专题	国家天文台_射电天文研究部
作者单位	1.Chinese Acad Sci, Natl Astron Observ, Beijing 100012, Peoples R China 2.Univ Chinese Acad Sci, Beijing 100049, Peoples R China 3.Chinese Acad Sci, Key Lab Radio Astron, Nanjing 210008, Jiangsu, Peoples R China 4.Univ Calif Berkeley, Dept Astron, 601 Campbell Hall 3411, Berkeley, CA 94720 USA 5.Macquarie Univ, Dept Phys & Astron, N Ryde, NSW 2109, Australia 6.Macquarie Univ, MQ Res Ctr Astron Astrophys & Astrophoton, N Ryde, NSW 2109, Australia 7.CSIRO Astron & Space Sci, Australia Telescope Natl Facil, POB 76, Epping, NSW 1710, Australia 8.CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA 9.Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia
推荐引用方式 GB/T 7714	Tang, Ningyu,Li, Di,Heiles, Carl,et al. OH Survey along Sightlines of Galactic Observations of Terahertz C[J]. ASTROPHYSICAL JOURNAL,2017,839(1).
APA	Tang, Ningyu.,Li, Di.,Heiles, Carl.,Yue, Nannan.,Dawson, J. R..,...&Wang, Jun-Jie.(2017).OH Survey along Sightlines of Galactic Observations of Terahertz C.ASTROPHYSICAL JOURNAL,839(1).
MLA	Tang, Ningyu,et al."OH Survey along Sightlines of Galactic Observations of Terahertz C".ASTROPHYSICAL JOURNAL 839.1(2017).