Kepler-91b could be on the brink of death — at least on astronomical time scales. The now-confirmed planet sits about 3,360 light-years from Earth near constellation Lyra and will be engulfed by its parent star in about 55 million years.
The star is a red giant that’s about the same mass as the sun but puffed out to six times the sun’s radius. Based on changes in light from the star, astronomers found that Kepler-91b is similar in size to Jupiter, sits about 11 million kilometers from the star and orbits it in a little more than six days. By comparison, Mercury sits roughly 46 million kilometers from the sun at the closest part of its orbit and circles the star in roughly 88 days.
Among confirmed planets around giant stars, Kepler-91b is the planet closest to its parent star, scientists report December 14 in an arXiv.org paper accepted for publication in Astronomy and Astrophysics.
Watching Kepler-91b could give astronomers a sense of what happens as a planet approaches death and also a preview of what may happen to Earth in a few billion years, the authors say.