Artist’s concept of a Kepler-1658-like system. Sound waves propagating through the stellar interior were used to characterize the star and the planet. Kepler-1658 b, orbiting with a period of just 3.8 days, was the first exoplanet candidate discovered by Kepler nearly 10 years ago. Photo courtesy of UH/Gabriel Perez Diaz/Instituto de Astrofísica de Canarias

The first exoplanet candidate identified by NASA’s Kepler Mission has been confirmed by an international team of astronomers, led by University of Hawaiʻi at Mānoa graduate student Ashley Chontos. The result was presented on March 5 at the 5th Kepler/K2 Science Conference held in Glendale, California, according to a UH news release.

Launched 10 years ago, the Kepler Space Telescope has discovered thousands of exoplanets using the transit method — small dips in a star’s brightness as planets cross in front of the star. Because other phenomena can mimic transits, Kepler data reveal planet candidates, but further analysis is required to confirm them as genuine planets.

Despite being the very first planet candidate discovered by NASA’s Kepler Space Telescope, the object now known as Kepler-1658 b had a rocky road to confirmation. The initial estimate of the size of the planet’s host star was incorrect, so the sizes of both the star and Kepler-1658 b were vastly underestimated. It was later set aside as a false positive when the numbers didn’t quite make sense for the effects seen on its star for a body of that size. Fortunately, Chontos’ first-year graduate research project, which focused on re-analyzing Kepler host stars, happened at the right time.

“Our new analysis, which uses stellar sound waves observed in the Kepler data to characterize the host star, demonstrated that the star is, in fact, three times larger than previously thought,” Chontos said. “This, in turn, means that the planet is three times larger, revealing that Kepler-1658 b is actually a hot Jupiter-like planet.”

With this refined analysis, everything pointed to the object truly being a planet, but confirmation from new observations was still needed.

For more on Kepler-1658 b, read the Institute for Astronomy news release