Development of Polarimetric Techniques to Investigate Habitability of Exoplanets
| Project/Area Number |
15K21296
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Astronomy
Solid earth and planetary physics
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| Research Institution | University of Hyogo |
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Principal Investigator |
Takahashi Jun 兵庫県立大学, 自然・環境科学研究所, 特任助教 (80648957)
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| Project Period (FY) |
2015-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2018: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2017: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2016: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2015: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
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| Keywords | 地球照 / 月食 / 偏光観測 / 生命探査 / 系外惑星 / 太陽系外惑星 / 検出可能性 / 光赤外線天文学 / 生命居住可能性 / 観測手法 |
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| Outline of Final Research Achievements |
We conducted polarimetry for lunar Earthshine and lunar eclipses. Following results have been obtained. (A) Earth's polarization degrees in the near-infrared tend to be larger when the ocean occupies a larger fraction in the reflecting surface. (B) The phase angle for the Earth's maximum polarization is larger in the near-infrared than that in the visible wavelengths. This observed trend probably corresponds to existence of an atmosphere with an Earth-like optical thickness. (C) We obtained the first-ever polarization spectra of the Moon during a lunar eclipse and detected a 2-3% polarization degree at wavelengths shorter than 600 nm and at absorption bands of molecular oxygen. The polarization degree of the Earth's transmitted light may depend on inhomogeneity of the cloud distribution.
These polarimetric signatures may be useful to investigate the habitability of exoplanets.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究では、月面地球照および月食の偏光観測により、「海の存在」、「大気の透明度」、「大気組成」、「雲の空間分布」に対応すると考えられる特徴を得た。これらはいずれも惑星における生命居住可能性に関係すると考えられ、中でも「海の存在」は生命活動に極めて重要である。本研究で得た観測特徴が太陽系外惑星に見られるかどうかを調べれば、系外惑星の生命居住可能性について情報を得ることができると期待される。つまり、本研究の成果は、有効な地球外生命探査の実現に貢献しうる。「我々は孤独なのか？」という人類社会が抱いてきた根源的な問いに答えるための一歩であるとも言える。
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Report
(6 results)
Research Products
(19 results)
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[Presentation] 皆既月食の偏光観測2015
Author(s)
高橋隼
Organizer
第6回光赤外線天文学大学間連携ワークショップ
Place of Presentation
国立天文台（東京都三鷹市）
Year and Date
2015-11-11
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