The fate of a planet depends on the speed and distance at which its star orbits. Those parameters dictate whether it will stay in your solar system or drift away from it. It can also happen that it loses part of its mass, evaporated by being too close to the orbiting star.
This is the case of the exoplanet that the Hubble space telescope has discovered: called GJ 3470b and with a size similar to that of Neptune, it is evaporating a hundred times faster than GJ 436b, another celestial body of similar mass and characteristics previously found.
David Sing, one of the authors of the study, notes that “GJ 3470b loses a significant part of its mass to a degree that we had not seen.” The team of this professor from Johns Hopkins University (USA) estimates that 35% of the mass of the object has already evaporated, and that in a few billion years it will have lost all its gas until it is reduced to its rocky core.
The discovery – published in the journal Astronomy & Astrophysics – is important, because it will allow astronomers to better understand how planets evolve.
Exhaust of gases
GJ 3470b, located 96 light years from Earth, orbits a red dwarf – a small and relatively cool star – known as GJ 3470. It does not resemble Neptune only in size. Like this, most of its mass and volume correspond to a gaseous atmosphere. And it is the outer layers of this that are evaporating because of the heat of the nearby red dwarf that keeps it close with its gravity.
It is a phenomenon that has been under the scrutiny of astronomers for some time, who have observed it on exoplanets such as super-earths, rocky worlds with a volume and mass halfway between Earth and gas giants such as Uranus and Neptune; and also in the so-called hot jupíteres, exoplanets larger than Jupiter but that orbit their stars up to a hundred times closer than our neighbor in the solar system.
The discovery has been made within the framework of the Panchromatic Comparative Exoplanet Treasury (PanCET) program, which is carried out with the Hubble space telescope and aims to measure the atmospheres of 20 exoplanets in the visible, infrared and ultraviolet light spectra. Sing explains that “we are beginning to understand how planets form. Observing in depth the atmospheres of those we study at PanCET will allow us to know how their environments influence them, and comparing them with each other we will know much more about how they evolve ”.
According to NASA, there are 3,869 confirmed exoplanets, 2,898 other heavenly bodies that could be confirmed, and 2,886 planetary systems. Research into these worlds will get a big boost when the James Webb Space Telescope comes into service, which is expected to launch in 2021. This observatory will be highly sensitive to helium, one of the main components of the atmospheres of extrasolar planets, which it will allow more detection and better analysis.
Image (NASA, ESA and D. Player / STScI): An artist’s illustration of the evaporation of hydrogen from the atmosphere of exoplanet GJ 3470b, caused by the heat of the orbiting star.
