| Project/Area Number |
19340058
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Particle/Nuclear/Cosmic ray/Astro physics
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| Research Institution | Konan University |
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Principal Investigator |
MURAKI Yasushi Konan University, 理工学部, 教授 (70013430)
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| Co-Investigator(Kenkyū-buntansha) |
SUMI Takahiro 名古屋大学, 太陽地球環境研究所, 助教 (30432214)
SAKO Takashi 名古屋大学, 太陽地球環境研究所, 助教 (90324368)
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| Co-Investigator(Renkei-kenkyūsha) |
ABE Fumio 名古屋大学, 太陽地球環境研究所, 准教授 (80184224)
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| Project Period (FY) |
2007 – 2010
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| Project Status |
Completed (Fiscal Year 2010)
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| Budget Amount *help |
¥18,590,000 (Direct Cost: ¥14,300,000、Indirect Cost: ¥4,290,000)
Fiscal Year 2010: ¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
Fiscal Year 2009: ¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
Fiscal Year 2008: ¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
Fiscal Year 2007: ¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000)
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| Keywords | 重力レンズ効果 / ダークマター / 太陽系外惑星 / 暗黒天体 / 暗天体 / 変光星 / 一般相対性理論 / 重力レンズ法 / 系外惑星 / 大マゼラン雲 / ミラ型変光星 / セファイド型変光星 / CCDカメラ / 二重レンズ効果 / ブラックスター / 褐色矮星 / スノーライン / 星の質量関数 / MOA望遠鏡 / マウントジョン天文台 / 木星 / 土星 / 地球型小型惑星 |
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| Research Abstract |
The Japan-NZ astronomy collaboration known as MOA (Microlensing Observations in Astrophysics) was formed in 1995 with the aim of searching for a component of dark matter in the form of MACHOs (Massive Compact Halo Objects) and also for extra-solar planets using the gravitational microlensing technique. This technique uses the gravitational fields of stars and other massive objects to effectively form large lenses in space as predicted by general relativity. The feasibility of the microlensing technique was pointed out by Bohdan Paczynski in 1986. He proposed monitoring as many stars as possible in the Magellanic Clouds and the galactic bulge to find gravitational lenses in the galactic halo or the galactic disc.
The MOA collaboration commenced observations in 1995 using a 0.6m telescope at the Mt John observatory in NZ. In 2005 a 1.8m telescope was installed at Mt John by Japan. Since that time more than 500 microlensing events have been found each year towards the galactic bulge. Also,
… More
events have been found towards the Magellanic Clouds.
The events found by MOA were made publicly available via the world wide web to enable other observatories to monitor selected events, in particular those with high magnifications. This resulted in the discovery of 16 extra-solar planets orbiting stars in the galactic disc and the galactic bulge. These planets were found just beyond the snowlines of their host stars. This is the region of maximum sensitivity of the microlensing technique, and it also the region where ice-giant and gas-giant planets form according to the core accretion theory. The data on these planets complements data being obtained on closer-in planets by the radial velocity and transit techniques.
In addition to the above discoveries, a new class of extra-solar planets was discovered by MOA. These planets are not bound to stars. They have masses similar to that of Jupiter, and they are approximately as abundant as stars in the galaxy.
Finally, the Konan University group of MOA completed the analysis of observations made between 1999 and 2005 towards the Large Magellanic Cloud with the 0.6m telescope at Mt John. Approximately 9,000 Miras and 13,000 Cepheid variable stars were found. Those results will be presented in elsewhere. Less
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