(Harvard-Smithsonian Center for Astrophysics) For the first time, astronomers have spotted an exoplanet whose orbit is decaying around an evolved, or older, host star. The stricken world appears destined to spiral closer and closer to its maturing star until collision and ultimate obliteration.
The discovery offers new insights into the long process of planetary orbital decay by providing the first look at a system at this late stage of evolution.
Death-by-star is a fate thought to await many worlds and could be the Earth’s ultimate adios billions of years from now as our Sun grows older.
“We’ve previously detected evidence for exoplanets inspiraling toward their stars, but we have never before seen such a planet around an evolved star,” says Shreyas Vissapragada, a 51 Pegasi b Fellow at the Center for Astrophysics | Harvard & Smithsonian and lead author of a new study describing the results.
“Theory predicts that evolved stars are very effective at sapping energy from their planets’ orbits, and now we can test those theories with observations.”
The findings were published today (Dec. 19) in The Astrophysical Journal Letters.
The ill-fated exoplanet is designated Kepler-1658b. As its name indicates, astronomers discovered the exoplanet with the Kepler space telescope, a pioneering planet-hunting mission that launched in 2009. Oddly enough, the world was the first new exoplanet candidate Kepler observed. Yet it took nearly a decade to confirm the planet’s existence, at which time the object entered Kepler’s catalogue officially as the 1658th entry.
Kepler-1658b is a so-called hot Jupiter, the nickname given to exoplanets on par with Jupiter’s mass and size but in scorchingly ultra-close orbits about their host stars. For Kepler-1658b, that distance is merely an eighth of the space between our Sun and its tightest orbiting planet, Mercury. For hot Jupiters and other planets like Kepler-1658b that are already very close to their stars, orbital decay looks certain to culminate in destruction.