An exoplanet almost 100 light-years from Earth disappears. And very quickly – by cosmic standards, astronomers are sounding the alarm. Using the Hubble Space Telescope, they were able to detect GJ 3470b, a medium-sized exoplanet with approximately Neptune that evaporates 100 times faster than a previously discovered planet of the same size. “This suggests that planets can lose a significant proportion of their entire mass,” says David Sing, a professor of astrophysics at Johns Hopkins University, author of the study.
“GJ 3470b loses more of its mass than any other planet we have seen so far; in just a few billion years, half of the planet will be gone. “
Does this mean that our planet can evaporate like this — with all its contents and inhabitants?
The results of the work were published in Astronomy & Astrophysics.
This study was part of the Panchromatic Comparative Exoplanet Treasury program, led by Singh. Its task is to measure the atmosphere of 20 exoplanets in ultraviolet, optical and infrared light as they rotate around their stars. PanCET is the largest exoplanet observation program launched on NASA’s Hubble telescope.
Astronomers are especially interested in how the planets lose their mass in the process of evaporation. Planets like super-earths and hot Jupiters, which move in orbits close to stars, are in very hot conditions that lead to deflation of the outer layers of the atmosphere.
While large exoplanets the size of Jupiter and exoplanets the size of the Earth are very common, medium-sized exoplanets with Neptune (about four times the size of Earth) are quite rare. Scientists attribute this to the fact that the atmospheres of these neptunes are blown away and they eventually turn into smaller planets.
It is quite difficult, however, to observe them in the process, because scientists can only investigate exoplanets in ultraviolet light, which limits them to study nearby stars at a distance of no more than 150 light years from Earth that are not covered with interstellar material.
GJ 3470b lies 96 light years and revolves around a red dwarf star in the general direction of the constellation Cancer.
Hubble discovered that exoplanet GJ 3470b lost much more mass and became much smaller exosphere than the first exoplanet studied the size of Neptune, GJ 436b, due to the low density and strong radiation of the parent star.
The low density of GJ 3470b leads to the fact that the planet is unable to maintain a heated atmosphere gravitationally, and if the star of the planet GJ 436b is from 4 to 8 billion years old, the star of GJ 3470b is only 2 billion years old. The young star is more active and powerful, and therefore emits more heat, heating the atmosphere of the planet.
According to the estimates of the Sing team, the GJ3470b may have already lost up to 35 percent of its total mass, and in a few billion years all gas will be lost, only the solid core will remain.
“We are beginning to better understand how planets form and what properties affect their overall composition,” says Sing. “Our goal in this study is to widely examine the atmospheres of these planets in order to determine how each planet is influenced by the environment. Comparing different planets, we can begin to compile a more general picture of their development. ”