Astronomers have discovered that a medium-sized planet, about the size of Neptune, GJ 3470b, is evaporating at a rate 100 times faster than a previously discovered planet of similar size, GJ 436b.
"This is proof that planets can lose a significant fraction of their total mass. GJ 3470b is losing more mass than any other planet we have known so far; in just a few billion years, half the planet may have disappeared, "he said. David Sing, a professor at Johns Hopkins University and the author of the study.
The study is part of the Panchromatic Comparative Exoplanet Treasury (PanCET) program, led by Sing, which aims to measure the atmospheres of 20 exoplanets in ultraviolet, optical and infrared light while orbiting their stars. PanCET is the largest exoplanet observation program that works with the Hubble Space Telescope NASA.
In this study, Hubble discovered that the GJ 3470b exoplanet had lost significantly more mass and had a remarkably smaller exosphere than the first studied Neptune size exoplanet, GJ 436b, due to its lower density and the reception of a radiation burst. strongest of its host star.
The lower density of GJ 3470b makes it unable to gravitationally cling to the hot atmosphere, and while the star that hosts GJ 436b was between 4,000 and 8,000 million years old, the star that houses GJ 3470b is only 2,000 million years old. ; a younger star is more active and powerful and therefore has more radiation to heat the planet's atmosphere.
Sing's team estimates that the GJ 3470b may have lost up to 35 percent of its total mass and, in a few billion years, all of its gas can be eliminated, leaving only one rocky core.
"We are beginning to understand better how the planets are formed and which properties influence their overall composition, "Sing says. Our goal with this study and with the global PanCET program is to analyze in general the atmospheres of these planets to determine how each planet is affected by its own environment. By comparing different planets, we can begin to reconstruct the general picture of how to evolve. "