An oceanic exoplanet 100 light years from Earth – Sciences et Avenir

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TOI-1452 b is an exoplanet located 100 light years from Earth in the constellation Draco. Initially detected by NASA’s Transiting Exoplanet Survey Satellite (TESS) telescope, it was later observed using some of the most advanced instruments on the ground. From these new observations it is clear that the planet could be an “ocean world”, that is, an object whose surface is covered almost entirely by a vast and deep layer of water. Its identification makes it a favorite target for the James Webb Space Telescope, whose early results far exceed astronomers’ expectations. A planet in a binary system It is, therefore, the TESS space telescope, which regularly observes the entire celestial vault, in search of planetary systems close to ours, that put researchers on the track of this exoplanet. In fact, it is designed to observe the tiny dips in brightness caused by the passage of a planet in front of its star, a transit in astronomical terms. That of TOI-1452 takes place every 11 days and corresponds to an exoplanet 70% larger than Earth. To TESS, the star TOI-1452 appears as a single light source: it is actually a binary whose two members are stars smaller than the Sun, separated by 97 AU, or about two and a half times the distance between the Sun and the Sun. pluto It is the PESTO instrument, installed at the Mont-Mégantic Observatory, in Quebec, that made it possible to resolve the two stars and confirm the presence of the exoplanet, in orbit around the larger of the two. Observations later confirmed by a Japanese team. SPIRou and PESTO to the rescue To determine the mass of the planet, the researchers observed the system with SPIRou, an instrument installed on the Canada-France-Hawaii telescope. It is an infrared spectropolarimeter that measures, by the Doppler effect, the minute variations in the speed of the stars induced by the planets revolving around them. After fifty hours of observation, the team led by Charles Cadieux, from the University of Montreal, managed to establish a measure. TOI-1452 b would have a mass approximately 5 times that of Earth. Other parameters, listed in an article in The Astronomical Journal, indicate that it is a rocky planet, but “its radius and mass suggest a much lower density than would be expected for a planet composed essentially of metal and rock, like the Earth,” explains the astronomer, in a press release. Although the Earth is called the “Blue Planet”, it actually holds very little water: less than 1% of its mass. Other stars contain much more, even in the solar system such as the satellites of Jupiter (Ganymede and Callisto) or Saturn (Titan and Enceladus). The precious liquid would constitute up to 30% of the mass and it would also be the case of TOI-1452 b. We add that the exoplanet is in the habitable zone of its star, that is to say that its surface temperature allows the presence of liquid water: it could therefore be an oceanic planet, a star that would be completely covered by a deep body. of water Artistic representation of the surface of TOI-1452 b. Credits: Benoît Gougeon, University of Montreal. So far, several other candidate planets are likely to possess the same supposed characteristics as TOI-1452 b. But the latter has other advantages that designate it for future complementary studies: it is relatively close to the Sun (100 ly) and above all its position in the sky means that it can be optimally observed by the James Webb telescope. NASA’s machine is powerful enough to carry out analyzes of its atmosphere, which will confirm the oceanic character of the star. However, its observation is not yet scheduled, slots to use the telescope are very hard to get…
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