Revealing the origin of dark gas around molecular clouds using the velocity-dispersion method

2017 Fiscal Year Final Research Report

• Project/Area Number: 26287030
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Astronomy
• Research Institution: Tokyo Gakugei University
• Principal Investigator: DOBASHI Kazuhito 東京学芸大学, 教育学部, 教授 (20237176)
• Co-Investigator(Kenkyū-buntansha): 前澤 裕之 大阪府立大学, 理学(系)研究科(研究院), 准教授 (00377780) ; 松本 倫明 法政大学, 人間環境学部, 教授 (60308004) ; 村田 泰宏 国立研究開発法人宇宙航空研究開発機構, 宇宙科学研究所, 准教授 (70249936) ; 中西 裕之 鹿児島大学, 理工学域理学系, 准教授 (90419846) ; 井上 剛志 名古屋大学, 理学研究科, 准教授 (90531294)
• Project Period (FY): 2014-04-01 – 2018-03-31
• Keywords: 電波天文学 / データベース天文学

Outline of Final Research Achievements

The purpose of our study is to quantify the components of “dark gas”. The dark gas is the gas which can be detected by the far-infrared dust emission or by gamma-ray, but cannot be traced by the HI 21cm line nor CO emission lines, and it is known to be abundant around dense molecular clouds. The origin of the dark gas should be either optically thick cold HI gas or diffuse molecular gas (H2) which cannot form or excite CO molecules. Using the new method that we named “velocity-dispersion method”, we analyzed the 21cm and CO emission lines around the Taurus molecular cloud, and found that the fraction of the cold HI gas in the dark gas is about 20%, and therefore the rest (~80%) of the dark gas should be the diffuse molecular gas without CO emission.

Free Research Field

天文学