Astronomers have discovered a planet that is estimated to be 10 billion years old, which is comparable to the age of the universe itself. The object orbits one of the oldest stars in the Milky Way, 280 light-years from Earth. The article with the research results has been accepted for publication in The Astronomical Journal.
The planet is 1.5 times larger than Earth, three times more massive than it and revolves around the star TOI-561 with an orbital period of 10.5 hours. The surface temperature of TOI-561 b is estimated to be 2480 Kelvin, with one side always facing the local sun. The discovery suggests that rocky planets can exist for a very long time, remaining stable.
The density of the planet is comparable to that of the Earth, which indicates that it is composed of light elements and is consistent with its age. Heavy elements are formed in the interiors of stars and are thrown into space with their death, including during supernova explosions. Therefore, the oldest stars have low metallicity, that is, they contain few elements heavier than hydrogen. Likewise, any ancient planet also cannot contain many heavy elements.
The existence of old planets also increases the chances of developing complex life. Vertebrates appeared on Earth no earlier than 500 million years ago, although the age of the Earth reaches 4.5 billion years.