![]() ![]() The root cause of the orbital decay experienced by Kepler-1658b is tides - the same phenomenon responsible for the daily rise and fall in Earth’s oceans. Over the past 13 years, the interval between Kepler-1658b’s transits has slightly but steadily decreased. All three instruments captured transits, the term for when an exoplanet crosses the face of its star and causes a very slight dimming of the star’s brightness. The watch started with Kepler and then was picked up by the Palomar Observatory’s Hale Telescope in Southern California and finally the Transiting Exoplanet Survey Telescope, or TESS, which launched in 2018. In the case of Kepler-1658b, according to the new study, its orbital period is decreasing at the miniscule rate of about 131 milliseconds (thousandths of a second) per year, with a shorter orbit indicating the planet has moved closer to its star.ĭetecting this decline required multiple years of careful observation. Measuring the orbital decay of exoplanets has challenged researchers because the process is very slow and gradual. ![]() 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. For Kepler-1658b, that distance is merely an eighth of the space between our sun and its tightest orbiting planet, Mercury. 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. Yet it took nearly a decade to confirm the planet’s existence, at which time the object entered Kepler’s catalogue officially as the 1,658th entry. Oddly enough, the world was the very first new exoplanet candidate Kepler ever observed. As its name indicates, astronomers discovered the exoplanet with the Kepler space telescope, a pioneering planet-hunting mission that launched in 2009. The ill-fated exoplanet is designated Kepler-1658b. The findings were published Monday in The Astrophysical Journal Letters. “Theory predicts that evolved stars are very effective at sapping energy from their planets’ orbits, and now we can test those theories with observations.” “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. ![]() The discovery offers new insights into the long-winded process of planetary orbital decay by providing the first look at a system at this late stage of evolution.ĭeath-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. The stricken world appears destined to spiral closer and closer to its maturing star until collision and ultimate obliteration. For the first time, astronomers have spotted an exoplanet whose orbit is decaying around an evolved, or older, host star. ![]()
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