最近的一项研究表明，所有七种 系外行星 TRAPPIST-1 恒星系统中的恒星具有相似的密度并且与地球相似 这很重要，因为它为理解类地物体的模型构建了知识库 系外行星 太阳系之外。
明星 in the galaxies have stellar systems comprising mainly of their 行星 and satellites. For example, our home stellar system viz. solar system has nine 行星 (of varying densities, sizes and compositions) and their satellites. Mercury, Venus, Earth and 三月，四个 行星 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 行星 Earth in the stellar system of Sun is unique in supporting life.
The quest for habitable worlds beyond Earth means search for habitable 行星 in the stellar systems of other 星星. There could be trillions of planets outside of the solar system. Such 行星 叫做 系外行星。有无数个中的任何一个 系外行星 支持生命？任何这样的 系外行星 只能是像地球一样具有坚硬岩石表面的陆地行星。陆地研究 系外行星 因此，这是一个非常有趣的研究领域。这 系外行星 社区是一个活跃的研究社区，致力于识别太阳系外恒星中潜在的生命孕育世界。
矮人 明星 TRAPPIST-1 was discovered in 1999. This ultra-cool star is situated at a distance of 40 light years. In 2016, three 系外行星 were reported in the stellar system of this 明星 which was revised to seven subsequently in 2017. Three of the exoplanets are thought to be in habitable zone (1) .
关于这些的知识 系外行星 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 行星 have rocky surfaces hence Earth-like terrestrial planets. And, these are closely located in 轨道 in close proximity to the star. The latest finding reported is that all the planets are of similar densities and made of similar materials.
运用 空间 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 系外行星 具有相似的密度和类似地球的成分，可能是因为铁含量比地球少一些 (2,3).
了解密度和组成的最新进展 行星 TRAPPIST-1 恒星系统中的研究意义重大，因为它为理解类地行星的模型构建了知识库 系外行星 太阳系之外。
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来源：
- 美国宇航局 2017 年新闻——美国宇航局望远镜揭示了最大一批围绕单颗恒星的地球大小、宜居带行星。 21 年 2017 月 XNUMX 日发布。可在线获取： 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 日访问。
- NASA 2021. JPL 新闻 - 系外行星 - 7 颗岩石 TRAPPIST-1 行星可能由类似的材料制成。 发表于 22 年 2021 月 XNUMX 日。 https://www.jpl.nasa.gov/news/the-7-rocky-trappist-1-planets-may-be-made-of-similar-stuff/
- Agol E.、Dorn C. 等人 2021 年。完善 TRAPPIST-1 的传输时间和光度分析：质量、半径、密度、动力学和星历。 行星科学杂志，第 2 卷，第 1 期。2021 年 22 月 XNUMX 日出版。DOI： https://doi.org/10.3847/PSJ/abd022
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