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 maart, 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.
De zoektocht naar bewoonbare werelden buiten de aarde betekent zoeken naar bewoonbare planeten in de sterrenstelsels van andere sterren. Er kunnen biljoenen planeten buiten het zonnestelsel zijn. Zulke planeten heten exoplaneten. Does any of the innumerable exoplaneten support life? Any such exoplaneet can only be terrestrial one with hard rocky surface like Earth. Study of terrestrial exoplaneten therefore, is a very interesting area of study. The exoplaneet community is an active research community in pursuit of identifying potential life-bearing worlds in the stars outside of the solar system.
De dwergster TRAPPIST-1 werd in 1999 ontdekt. Deze ultrakoele ster bevindt zich op een afstand van 40 lichtjaar. In 2016 drie exoplaneten werden gerapporteerd in het stellaire systeem van deze ster, dat vervolgens in 2017 werd herzien naar zeven. Drie van de exoplaneten bevinden zich vermoedelijk in de bewoonbare 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).
Deze nieuwste ontwikkeling in het begrip van dichtheid en samenstelling van 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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Bronnen:
- NASA 2017. Nieuws - NASA-telescoop onthult grootste partij planeten ter grootte van de aarde in bewoonbare zones rond een enkele ster. Geplaatst op 21 februari 2017. Online beschikbaar op: https://exoplanets.nasa.gov/news/1419/nasa-telescope-reveals-largest-batch-of-earth-size-habitable-zone-planets-around-single-star/ Betreden op 25 januari 2021.
- NASA 2021. JPL News - EXOPLANETS - De 7 Rocky TRAPPIST-1-planeten kunnen van vergelijkbaar materiaal zijn gemaakt. Geplaatst op 22 januari 2021. 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. Verfijning van de transit-timing en fotometrische analyse van TRAPPIST-1: massa's, stralen, dichtheden, dynamiek en efemeriden. The Planetary Science Journal, Volume 2, Number 1. Gepubliceerd op 2021 januari 22. DOI: https://doi.org/10.3847/PSJ/abd022
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