How long can a planet live? Based on this discovery, it is clear that they can live a long time . Thanks to NASA’s TESS (Transiting Exoplanet Reconnaissance Satellite) mission, a team of scientists has located a hot and rocky exoplanet, TOI-561b; a super-earth orbiting one of the oldest stars in our Milky Way.
The super-Earth, which orbits this old star, an orange dwarf called TOI-561, just 280 light-years distant from Earth, is 50% larger than our planet and three times its mass.
” We calculated that its density was the same as that of our planet. This is surprising because you would expect the density to be higher. This is consistent with the notion that the planet is extremely old. Its existence shows that the universe has been forming planets. rocky almost from its inception “, state the authors.
As a curiosity, the planet revolves around its host star in a dizzying orbit of 10.5 hours . That is, despite its size compared to our planet, it barely needs less than half an Earth day to make a full orbit (specifically 0.44 days).
“For every day you are on Earth, this planet orbits its star twice,” clarifies Stephen Kane, a planetary astrophysicist at the University of California at Riverside.
What is the cause of this unbridled orbit?
In part, it is due to the proximity of the planet to its star. It’s very close, which also causes surface temperatures of more than 1,700 ° C, too warm to support life as we know it today (although it may once have been possible).
“The stars in this region are chemically different, with fewer heavy elements such as iron or magnesium that are associated with the building of planets,” says Lauren Weiss, a postdoctoral researcher at the University of Hawaii and co-author of the work published in the journal The Astronomical Journal.
And it is that the heaviest elements of the cosmos – heavier than iron – are forged in the hearts of stars, in supernovae at the end of the life of a massive star and in collisions between dead stars as well. massive. Hence, the oldest stars in the universe are very metal-poor. And as for planets, as they age, they become less dense because there are not as many heavy elements available as when they were formed.
The star TOI-561, of low metallicity, as we have commented, is home to at least three small transiting planets, called TOI-561b (the super-Earth), TOI-561c and TOI-561d , and is one of the oldest planetary systems and poor in metals discovered so far in our galaxy.
“Although this particular planet is unlikely to be inhabited today, it may herald many rocky worlds yet to be discovered around the oldest stars in our galaxy,” concludes Kane.
Referencia: Lauren M. Weiss et al. 2021. The TESS-Keck Survey. II. An Ultra-short-period Rocky Planet and Its Siblings Transiting the Galactic Thick-disk Star TOI-561. AJ 161, 56; doi: 10.3847/1538-3881/abd409
