A recent study has revealed that all the seven Exoplaneten 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 Exoplaneten outside of solar system.
Stars in the galaxies have stellar systems comprising mainly of their planets and satellites. For example, our home stellar system viz. solar system has nine planets (of varying densities, sizes and compositions) and their satellites. Mercury, Venus, Earth and Mars, the four planets 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 planet Earth in the stellar system of Sun is unique in supporting life.
Die Suche nach bewohnbaren Welten jenseits der Erde bedeutet die Suche nach bewohnbaren Planeten in den Sternensystemen anderer Sterne. Es könnte Billionen von Planeten außerhalb des Sonnensystems geben. Solche Planeten werden genannt Exoplaneten. Does any of the innumerable Exoplaneten support life? Any such Exoplaneten can only be terrestrial one with hard rocky surface like Earth. Study of terrestrial Exoplaneten therefore, is a very interesting area of study. The Exoplaneten community is an active research community in pursuit of identifying potential life-bearing worlds in the stars outside of the solar system.
Der Zwergstern TRAPPIST-1 wurde 1999 entdeckt. Dieser ultrakühle Stern befindet sich in einer Entfernung von 40 Lichtjahren. Im Jahr 2016 waren es drei Exoplaneten wurden im Sternsystem dieses Sterns gemeldet, das später im Jahr 2017 auf sieben korrigiert wurde. Drei der Exoplaneten befinden sich vermutlich in der bewohnbaren Zone (1) .
The knowledge about these Exoplaneten 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 planets have rocky surfaces hence Earth-like terrestrial planets. And, these are closely located in orbits in close proximity to the star. The latest finding reported is that all the planets are of similar densities and made of similar materials.
Using space 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 Exoplaneten have similar densities and Earth-like composition possibly due to little less iron content than the Earth (2,3).
Diese neueste Entwicklung im Verständnis der Dichte und Zusammensetzung von Planeten in the stellar system of TRAPPIST-1 is significant because it builds the knowledge-base for a model of understanding of Earth-like Exoplaneten outside of solar system.
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Quellen:
- NASA 2017. Nachrichten – NASA-Teleskop enthüllt die größte Menge erdgroßer Planeten in der bewohnbaren Zone um einen einzelnen Stern. Veröffentlicht am 21. Februar 2017. Online verfügbar unter https://exoplanets.nasa.gov/news/1419/nasa-telescope-reveals-largest-batch-of-earth-size-habitable-zone-planets-around-single-star/ Zugriff am 25. Januar 2021.
- NASA 2021. JPL News – EXOPLANETS – Die 7 felsigen TRAPPIST-1-Planeten können aus ähnlichem Material bestehen. Gepostet am 22. 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. Verfeinerung des Transittimings und der photometrischen Analyse von TRAPPIST-1: Massen, Radien, Dichten, Dynamik und Ephemeriden. The Planetary Science Journal, Band 2, Nummer 1. Veröffentlicht am 2021. Januar 22. DOI: https://doi.org/10.3847/PSJ/abd022
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