A recent study has revealed that all the seven 外惑星 in the stellar system of TRAPPIST-1 have similar densities and Earth-like composition.This is significant because it builds the knowledge-base for a model of understanding of Earth-like 外惑星 outside of solar system.
星 in the galaxies have stellar systems comprising mainly of their 惑星 and satellites. For example, our home stellar system viz. solar system has nine 惑星 (of varying densities, sizes and compositions) and their satellites. Mercury, Venus, Earth and 火星、 XNUMXつの 惑星 closet to Sun have rocky surfaces hence are referred to as terrestrial planets. On the other hand, Jupiter, Saturn, Uranus, Neptune are made of gases. The 惑星 Earth in the stellar system of Sun is unique in supporting life.
The quest for habitable worlds beyond Earth means search for habitable 惑星 in the stellar systems of other 星. There could be trillions of planets outside of the solar system. Such 惑星 と呼ばれる 外惑星. Does any of the innumerable 外惑星 support life? Any such 太陽系外惑星 can only be terrestrial one with hard rocky surface like Earth. Study of terrestrial 外惑星 therefore, is a very interesting area of study. The 太陽系外惑星 community is an active research community in pursuit of identifying potential life-bearing worlds in the stars outside of the solar system.
ドワーフ 星 TRAPPIST-1 was discovered in 1999. This ultra-cool star is situated at a distance of 40 light years. In 2016, three 外惑星 were reported in the stellar system of this 星 which was revised to seven subsequently in 2017. Three of the exoplanets are thought to be in habitable zone (1) .
The knowledge about these 外惑星 in the stellar system of TRAPPIST-1 is growing continuously. The earlier studies had revealed that these planets are roughly the size and mass of the Earth. This meant these 惑星 have rocky surfaces hence Earth-like terrestrial planets. And, these are closely located in in close proximity to the star. The latest finding reported is that all the planets are of similar densities and made of similar materials.
使い方 スペース and ground-based telescopes, the scientists have done a precise measurement of the transit times (the time taken by the planets to transit the star measured indirectly by dips in the brightness of the star when the planets cross in front of it) which enabled them refine the mass ratios of the planets to the star. Following this, they carried out photodynamical analysis and derived the densities of the star and the planets. This revealed that all the seven 外惑星 have similar densities and Earth-like composition possibly due to little less iron content than the Earth (2,3).
の密度と組成の理解におけるこの最新の開発 惑星 in the stellar system of TRAPPIST-1 is significant because it builds the knowledge-base for a model of understanding of Earth-like 外惑星 outside of solar system.
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ソース：
- NASA 2017.ニュース– NASA望遠鏡は、単一の星の周りに地球サイズのハビタブルゾーンの惑星の最大のバッチを明らかにします。 21年2017月XNUMX日に投稿されました。オンラインで入手可能 https://exoplanets.nasa.gov/news/1419/nasa-telescope-reveals-largest-batch-of-earth-size-habitable-zone-planets-around-single-star/ 25年2021月XNUMX日にアクセス。
- NASA 2021. JPLニュース–太陽系外惑星-7つのロッキーTRAPPIST-1惑星は、同様のものでできている可能性があります。 22年2021月XNUMX日に投稿されました。 https://www.jpl.nasa.gov/news/the-7-rocky-trappist-1-planets-may-be-made-of-similar-stuff/
- Agol E.、Dorn C.、et al 2021. TRAPPIST-1のトランジットタイミングおよびフォトメトリック分析の改良：質量、半径、密度、ダイナミクス、および天体暦。 プラネタリーサイエンスジャーナル、第2巻、第1号。2021年22月XNUMX日発行。DOI： https://doi.org/10.3847/PSJ/abd022
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