Giant hydrogen cloud trails distant super-Earth
DOI: 10.1063/PT.5.028987
Los Angeles Times : Astronomers studying a Neptune-sized exoplanet have discovered that it is surrounded by an enormous cloud of hydrogen gas. As the planet Gliese 436b, about 30 light-years from Earth, closely orbits its red dwarf star, the planet’s atmosphere burns off and the cloud is created, along with a trail of gas that forms a comet-like tail. Astronomers discovered the giant gas cloud by using the Hubble Space Telescope to observe the planet’s transit as it crossed in front of its star. Although invisible at optical wavelengths, the cloud blocked more than 50% of the star’s UV radiation. Just four times the size of Earth, Gliese 436b is of interest to astronomers searching for smaller, more Earth-sized planets in order to better understand their origin and, hence, that of Earth.
