Another Neptune-Like Exomoon Candidate Reported (Kepler-1708 b-i)
takyon writes:
Despite an explosion of exoplanet discoveries since the 1990s, astronomers have not confirmed the discovery of a single exomoon. In fact, only around a dozen exomoon candidates have been put forward up to now.
In 2018, David Kipping (Columbia University) and Alex Teachey (now at Academia Sinica, Taiwan) were the first, tentatively reporting a possible Neptune-radius moon about 7,800 light-years from Earth: Kepler-1625 b-i. Now, the astronomers and other colleagues have announced the discovery of another exomoon, published January 14th in Nature Astronomy. However, just as before, they urge both caution and the need for further observations.
The putative exomoon, designated Kepler-1708 b-i, was found 5,700 light-years away, orbiting a Jupiter-size planet around a star similar to the Sun. The planet is on a Mars-like orbit, at about 1.6 astronomical units (a.u.). Its moon orbits about 12 planetary radii away, similar to Europa's distance from Jupiter. Unlike Europa, though, Kepler-1708 b-i is huge, about 2.5 times Earth's size. This means the moon would be unlike any satellite in our solar system.
Journal Reference:
David Kipping, Steve Bryson, Chris Burke, et al. An exomoon survey of 70 cool giant exoplanets and the new candidate Kepler-1708 b-i [open], Nature Astronomy (DOI: 10.1038/s41550-021-01539-1)
Yet another observation to add onto JWST's schedule.
Also at Scientific American.
Previously: First Exo-Moon Discovered?
First Known Exomoon May Have Been Detected: Kepler 1625b i
New Evidence Supports Existence of Neptune-Sized Exomoon Orbiting Kepler-1625b
Exomoon Confirmation Remains Elusive
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