A team of astronomers announces the discovery of a rocky "super-Earth" planet orbiting one of the oldest stars in the Milky Way. On the other hand, the chances that it is inhabited are almost nil.
To fully understand the processes of planetary formation and evolution, researchers must observe and characterize as many worlds as possible, from the youngest to the oldest. In this sense, progress has been made in recent years thanks to exoplanet hunters.
A few months ago, for example, observations made with the Very Large Telescope (VLT), in Chile, made it possible to appreciate the birth of a new planetary system 520 light years from Earth. More recently, astronomers relying on NASA's TESS satellite and the WM Keck Observatory in Hawaii have identified a planet "at the other end of the road".
You will find this world, called TOI-561b, about 280 light years away . It is a rocky "super-earth" about 50% larger and three times more massive than our planet. Surprisingly, the researchers also found that the density of TOI-561b was similar to that of Earth, suggesting that this planet is incredibly ancient .
Heavy elements such as iron and magnesium are indeed made by ongoing fusion reactions in the cores of massive stars. Their abundance has therefore accumulated over time, to the rhythm of the explosions of stars which have seeded the Universe with their elements. Here, TOI-561b's low density compared to its size suggests that it contains relatively few heavy elements, hence its apparent age. According to the authors, this world probably formed about 10 billion years ago .
These suspicions are also confirmed by the presence of its host located in the thick galactic disk, which hosts a rare population of stars with significantly fewer heavy elements than typical stars. of the Milky Way. Simply put, TOI-561b is one of the oldest rocky planets ever discovered , orbiting one of the oldest stars in the galaxy. "Its existence shows that the Universe formed rocky planets very early in its history" , notes Lauren Weiss, of the University of Hawaii and lead author of the study.
Another interesting point:TOI-561b evolves very close to its star, completing a lap of the latter in just twelve hours . As you will have understood, a year on this planet is equivalent to half a day here on Earth. As a result, this world displays an average surface temperature of over 1726 degrees Celsius , which naturally seems far too hot to support any form of life as we know it , also points out the University of California at Riverside, which participated in the research.
Finally, the researchers also report the presence of two other known planets in addition to TOI-561b. In contrast, these other two planets are too large and not dense enough to be rocky. In other words, they are gas giants, like Saturn or Jupiter. You will find the details of this work in The Astronomical Journal .
