Scientists have found an atmosphere around a low-mass super-Earth for the first time, an important development in our hunt for habitable worlds.
The planet is called Gj 1132b, and it’s located 39 light-years from Earth. It was studied by scientists from the Max Planck Institute for Astronomy (MPIA) using the 2.2-meter (7.2 foot) ESO/MPG telescope in Chile. The findings are published in The Astronomical Journal.
By imaging the star, they were able to see the slight decrease in brightness as the planet passed in front, and they deduced an atmosphere was absorbing some of the light, possibly containing methane and water. They came to this conclusion by imaging the planet in multiple wavelengths, and at one infrared wavelength, the planet appeared to be larger.
“This suggests the presence of an atmosphere that is opaque to this specific infrared light (making the planet appear larger), but transparent at all the others,” a statement from the MPIA read.
The planet is about 1.4 times the size and 1.6 times the mass of Earth, and orbits its star in just 1.6 days, so in our current understanding of exoplanets it is unlikely to be habitable – being too close and hot for liquid water to exist on its surface.
But it does make things interesting. The star it orbits is an M dwarf, which are prone to bursts of activity and should blast away the atmospheres of nearby planets. This atmosphere appears to have endured for billions of years, suggesting worlds around these stars are not necessarily so barren.
For a system like TRAPPIST-1, this is hugely important. Earlier this year, it was announced there were at least three potentially habitable rocky worlds orbiting this nearby ultra-cool dwarf star, 39 light-years away. Debate has persisted about whether they could retain atmospheres, however, owing to their star’s activity. Gj 1132b suggests that they can.
This is not the first atmosphere discovered around a super-Earth. That honor went to the Hubble Space Telescope in February 2016, which observed a dry atmosphere devoid of water vapor around the exoplanet 55 Cancri e, 40 light-years from Earth and eight times the mass of our planet.
However, it represents another important discovery in our exoplanet research, and continues to paint a picture of what a fascinatingly diverse universe is out there. That this world can cling onto an atmosphere raises all sorts of hope for finding life elsewhere.
