Astronomers spot intriguing super-Earth in dwarf star's habitable zone
Astronomers have discovered a "super-Earth" orbiting a red dwarf star within the habitable zone. It could potentially host liquid water on its surface, a key factor for exoplanet habitability. The planet, called TOI-715b, is 1.55 times the Earth's radius and may have a smaller, roughly Earth-sized sibling in the same region. If confirmed, this would be the tiniest habitable zone planet discovered by NASA's Transiting Exoplanet Survey Satellite (TESS), as reported in the Monthly Notices of the Royal Astronomical Society.
TOI-715b's orbit and characteristics
The larger planet, TOI-715b, orbits its star in just 19 Earth days and is located 137 light-years away. Although such a tight orbit usually results in extreme temperatures in other star systems, red dwarfs are much dimmer, allowing for potentially habitable conditions. However, NASA cautions that these findings are unconfirmed and that both suspected exoplanets are inside a relatively narrow or "conservative" habitable zone. This research was led by Georgina Dransfield, a postdoctoral researcher at the University of Birmingham.
What is CHZ?
The idea of a conservative habitable zone (CHZ) was first posed by scientist RK Kopparapu, in a research paper in 2014. CHZ can be described as a region surrounding a star, where a rocky planet gets between 0.42 and 0.842 as much solar insolation (actual amount of solar radiation over a unit horizontal surface over a specified time) as Earth does. Any rocky planet which receives that much energy, lies in the CHZ, regardless of distance.
Future observations and implications
To verify the presence of an atmosphere or determine if either planet is a "water world," more sensitive telescopes like NASA's James Webb Space Telescope could be used. The possibility of finding abundant water in an exoplanet's atmosphere has scientists thrilled about potential evidence of extraterrestrial life. This discovery follows last year's detection of an apparently "hycean" ocean planet named K2-18b, which has an atmosphere rich in hydrogen and methane.
