Exoplanet TOI-849b Might Be the Leftover Core of a Gas Giant Planet

Artist’s impression showing a Neptune-sized planet in the Neptunian Desert. It is extremely rare to find an object of this size and density so close to its star. Image credit: University of Warwick/Mark Garlick

Extrasolar planets or “exoplanets” are planets that orbit around stars other than our Sun. With increasingly sophisticated technology and detection methods, more exoplanets are being discovered. One method for identifying an exoplanet is the transit method. Using this method, exoplanets can be detected and characterized by measuring the light that is blocked when an exoplanet moves in front of its star. In 2018, NASA’s Transiting Exoplanet Survey Satellite (TESS), launched into space to observe transiting exoplanets. A recent study using TESS data, led by David Armstrong from the University of Warwick, identified features associated with the exoplanet TOI-849b. A rare characteristic combination of size and radius is a designation of exoplanets known as hot-Neptunes. Hot-Neptunes are a rare category because of photoevaporation and tidal disruption. The discovery of TOI-849b fits into the hot-Neptune category, but with some distinct differences, such as a smaller radius than Neptune, much heavier mass, and similar Earth density. The lack of atmosphere coupled with its high mass and relative density make it one of the densest planets of its size discovered to date. Detailed study of this system, which includes interior-structure modeling that focused on the gaseous envelopes, determined that exoplanet TOI-849b could be the remnant of a giant planet core. READ MORE