Ionization Profiles of Galactic H ii Regions

doi:10.3847/1538-4365/aaf6a5

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	Ionization Profiles of Galactic H ii Regions
	Luisi,Matteo 1,2; Anderson,L. D.1,2,3; Liu,Bin 4; Roshi,D. Anish 5; Churchwell,Ed 6
刊名	The Astrophysical Journal Supplement Series
	2019-02-20
卷号	241 期号:1
关键词	Hii regions ISM: abundances ISM: bubbles photon-dominated region (PDR) radio lines: ISM
ISSN号	0067-0049
DOI	10.3847/1538-4365/aaf6a5
英文摘要	Abstract Using Green Bank Telescope radio recombination line (RRL) data, we analyze the role of leaking radiation from H ii regions in maintaining the ionization of the interstellar medium (ISM). We observed a sample of eight Galactic H ii regions of various sizes, morphologies, and luminosities. For each region, the hydrogen RRL intensity decreases roughly as a power-law with the distance from the center of the region. This suggests that radiation leaking from the H ii region is responsible for the majority of surrounding ionized gas producing RRL emission. Our results further indicate that the hydrogen RRL intensity appears to be fundamentally related to the H ii region sizes traced by their photodissociation regions, such that physically smaller H ii regions show a steeper decrease in intensity with an increasing distance from the region centers. As a result, giant H ii regions may have a much larger effect in maintaining the ionization of the ISM. For six of the eight observed H ii regions, we find a decrease in the 4He+/H+ abundance ratio with an increasing distance, indicating that He-ionizing photons are being absorbed within the ionization front of the H ii region. There is enhanced carbon RRL emission toward directions with strong continuum background, suggesting that the carbon emission is amplified by stimulated emission.
语种	英语
出版者	The American Astronomical Society
WOS记录号	IOP:0067-0049-241-1-AAF6A5
内容类型	期刊论文
源URL	[http://ir.bao.ac.cn/handle/114a11/25122]
专题	中国科学院国家天文台
作者单位	1.Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506, USA 2.Center for Gravitational Waves and Cosmology, West Virginia University, Chestnut Ridge Research Building, Morgantown, WV 26505, USA 3.Adjunct Astronomer at the Green Bank Observatory, P.O. Box 2, Green Bank, WV 24944, USA 4.CAS Key Laboratory of FAST, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China 5.National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475, USA 6.Department of Astronomy, University of Wisconsin-Madison, Madison, WI 53706-1507, USA
推荐引用方式 GB/T 7714	Luisi,Matteo,Anderson,L. D.,Liu,Bin,et al. Ionization Profiles of Galactic H ii Regions[J]. The Astrophysical Journal Supplement Series,2019,241(1).
APA	Luisi,Matteo,Anderson,L. D.,Liu,Bin,Roshi,D. Anish,&Churchwell,Ed.(2019).Ionization Profiles of Galactic H ii Regions.The Astrophysical Journal Supplement Series,241(1).
MLA	Luisi,Matteo,et al."Ionization Profiles of Galactic H ii Regions".The Astrophysical Journal Supplement Series 241.1(2019).