Study of massive star formation process in Orion region via astrometric observation

• Project/Area Number: 26400225
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Astronomy
• Research Institution: Niigata University
• Principal Investigator: Nishi Ryoichi 新潟大学, 自然科学系, 准教授 (80252419)
• Project Period (FY): 2014-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000); Fiscal Year 2017: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2016: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2015: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2014: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
• Keywords: 星形成 / 位置天文学 / オリオン巨大分子雲 / 恒星系 / 巨大分子雲 / Gaia / JASMINE / 位置天文衛星 / 大質量星

Outline of Final Research Achievements

We study pre-main sequence stars in Orion region using astrometric data of the Gaia data release 2 (DR2). Gaia is astrometric spacecraft of European Space Agency and DR2 was published on 25 April 2018.
Using the Gaia DR2 astrometric parameters, we draw the color magnitude diagram (H-R diagram). There is a branch of main sequence stars. And we can see another branch of young pre-main stars. We plot the proper motion distribution and show that young stars are highly concentrated into small area on the plan. This means that almost all of star forming molecular clouds in Orion region have been well correlated on the proper motion plane and also stars are formed calmly for most cases

Academic Significance and Societal Importance of the Research Achievements

大質量星は非常に明るく輝き、周囲の星間雲への影響が大きい。そして、銀河系の進化を考える上でも重要である。しかし、その形成過程はまだまだ理解が不十分である。そこで、近傍の大質量星形成領域であるオリオン広領域での星形成過程についてこれまでと異なる手法による研究結果は重要である。また、その結果は大質量星が連鎖的に形成されるというモデルの予想とは異なっており、新たな形成モデルの構築の必要性も明らかになった。

Research Products

• [Presentation] Gaia DR2に基づく Orion OB I アソシエーションの星形成史の解析 (2019)
  • Author(s): 西亮一
  • Organizer: 日本天文学会春季年会
• [Presentation] On the relation of star formation and Orion giant molecular clouds (2018)
  • Author(s): 西亮一
  • Organizer: XXX IAU General Assembly
  • Int'l Joint Research
• [Presentation] Gaia DR2を用いたオリオン領域の星形成過程の解析 (2018)
  • Author(s): 西亮一
  • Organizer: 日本天文学会秋季年会
• [Presentation] Nano-JASMINE sciecne (2016)
  • Author(s): Ryoichi Nishi
  • Organizer: Gaia-JASMINE joint meeting
  • Place of Presentation: National Astronomical Observatory of Japan（東京都三鷹市）
  • Year and Date: 2016-12-06
  • Int'l Joint Research
• [Presentation] Nano-JASMINE science activity and requirement of joint data (2014)
  • Author(s): Ryoichi Nishi
  • Organizer: Gaia CU9 Plenary meeting 2014
  • Place of Presentation: Wienna, Austria
  • Year and Date: 2014-07-08
• [Remarks] 誰でも使えるGaiaデータ
  • URL: https://astro1.sc.niigata-u.ac.jp/~nishi/Gaia/GaiaDR1top.html