A planetary system comprising an orange dwarf-type star called “TOI-561” around which three exoplanets, including an ultra-short period super-Earth, have been discovered by astronomers using the Transiting Exoplanet Survey Satellite (TESS) and the spectrometer high resolution from the Keck I telescope at the WM Keck Observatory in Hawaii.
According to astronomers, the star TOI-561 , surrounded by its three rocky planets called TOI-561b, TOI-561c and TOI-561d , is about 10 billion years old. As a result, this planetary system is almost as old as the Universe itself, about 13.7 billion years old.
This discovery proves that there are worlds that can remain stable for very long periods of time, according to astronomers, who recently shared their findings in an Astronomical Journal article.
One of the oldest planetary systems ever discovered
TOI-561, is also known as TYC 243-1528-1. It is one of the oldest stars in the Milky Way, and it is located 280.5 light years from us in the constellation Sextant. Characterized by a mass and a size of approximately 80% of those of the Sun, it belongs to a rare population of stars called “galactic thick disc stars” endowed with a particular chemical composition, in particular with less heavy elements, such as than iron and magnesium.
With the three small planets in transit that it hosts, it forms one of the oldest and poorest planetary systems identified in the Milky Way.
Three planets larger than Earth orbit TOI-561
Regarding the latter, the inner planet TOI-561b, which is a superEarth, has a mass equivalent to 3.2 times and a radius 1.45 times greater than the Earth, with a density of 5.5 g / cm 3 ( the same as that of our planet). This planet orbits around TOI-561 rotating on itself in 10.5 hours and the temperature on its surface rises to over 1,727 ° C, a heat incompatible with life even if it was perhaps the case formerly.
This planetary system also includes TOI-561c and TOI-561d outer planets weighing respectively 7 and 3 times more than the Earth for radii respectively 2.9 and 2.3 times that of our planet.