Updated:
Save
His name is TOI-500 b, is 155 light-years away and is one of the most Earth-like planets discovered so far. However, this should not mislead us. Its extraordinary proximity to its star makes it a real hell, with surface temperatures exceeding 1,300 degrees Celsius. It is, therefore, a world of lava, unusable for life but which scientists believe could faithfully reflect what will happen to ours in billions of years. “It’s like seeing the Earth of the future,” the astrophysicist explains to ABC Luisa Maria Serranofirst author of a recently published paper on the new planet in Nature Astronomy.
TOI-500 b orbits its star once every 13 hours. It is, therefore, a good example of what scientists call ‘ultra-short period planets’ (USP), which are characterized by having orbits that last less than a day. Such worlds are known to be born in chaotic orbits and very far from their stars, only to end up too close to them later due to violent collisions with other objects in formation.
But according to Serrano, «TOI-500 b is special, because it seems to have reached its position differently than normal. In fact, it could not have suffered any violence, and instead of forming in chaotic orbits, as usual, it was born directly in a circular and stable orbit. And from there, quietly and over 2,000 million years, it continued to rotate while its orbit was restricted little by little, very slowly».
A system with 4 planets
TOI-500 b is part of a system in which there are at least three other planets, also with circular orbits although all of them much farther from their sun, a K-type or ‘orange dwarf’ star. However, unlike its peers, the new world is an incredibly short distance from its parent star, just under 2 million km. «In our Solar System -explains Serrano-, such a world could not exist. The surface temperature of TOI-500 b is 1,343 degrees, well above the 430 degrees reached by, for example, Mercury, the first planet in our system. Probably this world does not have an atmosphere, or if it does it is very metallic, and we believe that its entire surface is lava. TOI-500 b survives these conditions because its star is a K-type, somewhat cooler than our Sun, which allows the planet to be so close.” Mercury, the closest planet to the Sun in our system, is 58 million km from it.
An analog of Earth
Very similar in size to Earth, just 1.16 times larger than our planet, TOI-500 b is, however, 1.65 times its mass. It is, therefore, a solid and rocky planet. It was first observed with the Transiting Exoplanet Survey Satellite (TESS) Space Telescope in 2018 by Davide Gandolfi, director of the Department of Astrophysics at the University of Turin and co-author of the study, but its existence has not been confirmed until now. As Serrano explains to ABC, “it is one of the smallest and most Earth-like planets discovered so far, and it is the first USP planet observed in a system with other planets that formed according to a non-violent model, which is fascinating. . Now, according to our simulations, the planet is stable.”
Despite its truly hellish conditions, the researchers maintain that TOI-500 b is one of the top 10 planets that exist to study the atmospheres. But how is this possible if you think it doesn’t even have an atmosphere?
According to Serrano, «TOI-500 b lost its primary atmosphere. In Astronomy, the atmosphere is not the same as in colloquial language. The primary atmosphere is what the planet takes from the protoplanetary disk, from its volatile materials. It is usually rich in hydrogen, which adheres to rocks. But a planet so close to its sun can’t support it, and the hydrogen evaporates. TOI-500 b is too small and without enough gravity to hold it. If it has an atmosphere, it will be secondary, made of the gases that emanate from the planet itself. If so, we think it might resemble Jupiter’s satellite Io.”
An image of the future Earth
According to the researchers, the new planet could be a true reflection of what it will be like. Earth in billions of years, when the Sun becomes a red giant much larger than it is now. «Right now -says Serrano- we are on a planet where you can still live. It’s getting warmer though, and we’re moving toward a Venus-type world, with a strong global greenhouse effect. But when the Sun becomes a red giant, before it dies, it will grow so large that it will swallow the inner planets, like Mercury or Venus, and perhaps even the Earth. Even if it doesn’t, by then our planet will be so close to the Sun that its entire surface will turn into a large expanse of lava, similar to what TOI-500 b is now. In that sense, looking at that planet is like looking at the Earth of the future.”
See them
comments