Astronomers have discovered a superhot exoplanet with the composition of Mercury.
The TESS Space Telescope has discovered a red-hot exoplanet the size of Mars, similar in composition to Mercury, with a year that lasts only eight hours. It is one of the smallest exoplanets discovered to date. Planet GJ 367 b is located about 31 light years from the Sun, which allows astronomers to study its properties in sufficient detail.
Astronomers working with the TESS space telescope have reported the discovery of the exoplanet GJ 367 b, which has an ultra-short orbital period around its star, a red dwarf. A year on this planet lasts only eight hours. It is comparable in size to Mars and half the mass of Earth, making it one of the smallest planets discovered to date. Information about this discovery is contained in a press release from the Massachusetts Institute of Technology.
TESS - Transiting Exoplanet Survey Satellite is a space telescope specially designed for the discovery of exoplanets by the transit method - when passing over the disk of the parent star. It was developed by the Massachusetts Institute of Technology as part of the NASA Minor Research Program and launched on April 18, 2018, on a Falcon 9 launch vehicle. TESS studied the southern sky that includes the star GJ 376 for a month in 2019, tracking changes in the brightness of stars close to Earth. The TESS data was then sieved for periodic dips in the star's emission, which would indicate that a planet that crosses the stellar disk briefly blocks its light. To confirm that the detected object GJ 367 b is indeed an ultrashort-periodic planet, additional observations were made using a ground-based spectrograph that measures its radial velocity - the HARPS instrument, the High Accuracy Radial Velocity Planet Searcher, installed on the telescope of the European Southern Observatory in Chile.
Planet GJ 367 b is located 31 light years from the Sun, which allows astronomers to study its properties in sufficient detail. Its diameter is 72% of the Earth's, and its mass is 55% of the Earth's mass. It is believed to be composed of rock and has a solid core of iron and nickel, similar to Mercury. The iron core should occupy 86% of the interior of the planet.
“ We found a planet the size of Mars that has the composition of Mercury, ” said Roland Vanderspeck, a leading researcher at MIT. " It is one of the smallest planets discovered to date and orbits an M-class dwarf in a very close orbit. "
Astronomers estimate that due to its extreme proximity to the star, GJ 376 b receives 500 times more radiation than the Earth from the Sun. As a result, the daytime side of the planet heats up to 1500° C. At such extreme temperatures, any atmosphere would have to evaporate, and the existence of life - at least in the form we are used to - on this planet is, of course, impossible. However, it is possible that there are other potentially habitable planets in the same system. The presence of several planets at once in red dwarfs is a very common phenomenon. Red dwarfs are much smaller and colder than the Sun, these include stars of spectral types M or K on the Hertzsprung-Russell diagram. In this case, it is an M-dwarf, and the discovery of one planet in it indicates the possible presence of several more exoplanets in this system.
" For stars of this class, planets in the habitable zone must orbit the star in about a month, " explains George Ricker of the Kavli Institute of Astrophysics and Space Research at MIT, who was also involved in the study. Since this star is so close to us and so bright, we have a good chance of finding other planets in this system. It all looks like a sign that says, " Look for additional planets here! "
By continuing to study GJ 367 b and its star, scientists hope to find signs of the presence of other planets in the system. The properties of these planets, such as their size and distance from the star, may provide clues to how GJ 367 b and other ultrashort-period planets originate.
“ Understanding how these planets are moving closer to their parent stars is kind of a detective story, ” says Natalia Guerrero, a member of the TESS group. - Why is there no external atmosphere on this planet ? How did she get close to her star ? Was this process gradual or disastrous ? I hope this system will allow us to understand all this. "
Ultra-short-period planets, USP, are considered to be those that orbit their stars at an extremely small distance, completing one revolution in orbit - corresponding to one year - in less than 24 hours. Most likely, they are all locked - one of their sides is constantly facing its luminary. How these planets ended up in such extreme configurations remains one of the most important scientific mysteries.
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