“Hot Jupiter” Is in a Possible Death Spiral
https://eos.org/articles/hot-jupiter-is-in-a-possible-death-spiral
Excerpt: Kepler’s first exoplanet is migrating toward its star, an evolved subgiant that is much bigger than first thought. ...Kepler-1658b is the first inspiraling planet discovered around an “evolved” star—one that has moved out of its prime life. The star—Kepler-1658—is about 1.5 times the mass of our Sun and has expanded to almost 3 times the Sun’s diameter in its late stages of life, earning it the designation of subgiant. Should Kepler-1658b maintain its current path, it will meet its fate in about 2.5 million years. ...Early in its mission, Kepler recorded such dips from Kepler-1658. However, astronomers had initially cataloged the star as belonging to the main sequence—stars like the Sun that are still burning the hydrogen in their cores. ...Kepler-1658b was discarded as a false positive and forgotten about. ...That is, until Chontos began looking at vibrations on the surfaces of stars in the Kepler catalog...—a technique known as asteroseismology—revealed details about the stars’ interiors. ...they showed that the star was much farther along in life than expected and hence about 3 times bigger. That meant the transiting planet was 3 times larger as well, making it big enough and bright enough to contribute to the system’s overall brightness when it wasn’t eclipsed by the star. “Suddenly, a close-in hot Jupiter made sense,” Chontos said. “That discovery was completely accidental.”...