An exoplanet recently discovered by astronomers represents quite a find. The planet, called GJ 367b , is smaller than Earth, denser than iron and hot enough to melt, according to scientists in the journal Science that publishes the study.
“We believe that the surface of this exoplanet could be molten,” says astronomer Kristine Wei Fun Lam of the Planetary Research Institute of the German Aerospace Center in Berlin, Germany.
The boiling new world, which revolves around its star in an ultra-close range, is among the most curious exoplanets found to date. It revolves around its host star every 7.7 hours . It is an ultrashort period planet.
These types of worlds are smaller and more compact than usual and complete their orbit in less than 24 hours. How these planets came to have such extreme configurations is one of the continuing mysteries of exoplanetary science. This, as we see, has an extremely close orbit with respect to its star. This leads astronomers to estimate that GJ 376 b receives 500 times more radiation than the Earth receives from the Sun. As a result, the day side of the planet boils up to 1,500 ° C. Logically, with those temperatures, if at some point it had an atmosphere, it would have evaporated.
The fact, in addition, that it is approximately the size of Mars and half the mass of Earth, makes it one of the lightest planets discovered to date. Its density is 8.1 grams per cubic centimeter. The density of the Earth is 5.51 grams per cubic centimeter. It has a density equivalent to that of almost pure iron (slightly more).
Its star is 31 light years from our own Sun. It is so close that astronomers have been able to find out its properties, such as the fact that we know that it is a rocky planet and that it probably contains a solid core of iron and nickel. similar to the interior of Mercury.
Its transits were detected by NASA’s Exoplanet Hunting Space Telescope, TESS, which looks at regions of the sky for long periods, looking for dips in starlight to infer a planet in transit, as well as the HARPS ground-based spectrograph. of the European Southern Observatory in Chile.
All in all, the exoplanet is just over 9,000 kilometers in diameter.
Scientists believe it is the result of a giant impact with another planet that removed most of its outer layers. GJ 367b could have formed after a similar collision. It could also have been a gaseous planet whose atmosphere was destroyed by radiation from its star.
“Understanding how these planets get so close to their host stars is kind of a detective story, ” says Natalia Guerrero, a member of the TESS team. “Why is this planet lacking its outer atmosphere? How did you get closer? Was this process peaceful or violent? Hopefully this system will give us a little more information. “
Referencia: Kristine W. F. Lam, GJ 367b: A dense ultra-short period sub-Earth planet transiting a nearby red dwarf star, Science (2021). DOI: 10.1126/science.aay3253. www.science.org/doi/10.1126/science.aay3253