In their hunt for elusive exomoon candidates, astronomers have checked out 70 cool gasoline giants discovered by NASA’s Kepler area telescope. They’ve discovered just one sign that would point out an exomoon, about 2.6 occasions bigger than Earth, orbiting a Jupiter-sized exoplanet referred to as Kepler-1708b. Named Kepler-1708b-i, it joins Kepler-1625b-i as one other instance of an unexpectedly massive exomoon candidate — echoing the shock that hot-Jupiter discoveries elicited within the mid-Nineteen Nineties.
An artist’s impression of the gasoline big Kepler-1708b, its moon Kepler-1708b-i, and their father or mother star. Image credit score: Helena Valenzuela Widerström.
In the final three many years, greater than 4,000 planets round stars aside from the Sun have been found.
These alien worlds show outstanding variety, from extremely eccentric Jupiters to compact, coplanar techniques of rocky planets.
In an effort to know the formation and evolution of such techniques, extra detailed information about their surroundings and properties is sought — such because the existence and nature of potential.
Given the abundance of moons in our Solar System, it’s affordable to presume that exomoons will reside round some exoplanets — which has motivated efforts to detect them.
One of probably the most promising methods for searching for exomoons focuses on transiting planets.
“Astronomers have found more than 10,000 exoplanet candidates so far, but exomoons are far more challenging. They are terra incognita,” mentioned lead writer Professor David Kipping, an astronomer within the Department of Astronomy at Columbia University.
In the present examine, Professor Kipping and his colleagues appeared on the pattern of the coldest gasoline big planets captured by NASA’s planet-hunting spacecraft, Kepler.
After scanning 70 planets in depth, they noticed the brand new exomoon candidate orbiting Kepler-1708b, a large planet about 5,500 light-years away within the course of the Cygnus and Lyra constellations.
“It’s a stubborn signal. We threw the kitchen sink at this thing but it just won’t go away,” Professor Kipping mentioned.
The new exomoon candidate, Kepler-1708b-i, is a couple of third smaller than the Neptune-sized moon that the crew earlier discovered orbiting an analogous Jupiter-sized planet, Kepler-1625b.
“Both supermoon candidates are likely made of gas that has piled up under the gravitational pull caused by their enormous size,” Professor Kipping mentioned.
“If one astronomer’s hypothesis is correct, the moons may have even started life as planets, only to be pulled into the orbit of an even bigger planet like Kepler-1625b or Kepler-1708b.”
Both moons are positioned removed from their host star, the place there’s much less gravity to tug at planets and strip off their moons.
In truth, the astronomers sought out chilly, big gasoline planets on extensive orbits of their seek for exomoons exactly as a result of the analog in our personal Solar System, Jupiter and Saturn, have greater than 100 moons between them.
“If other moons are out there, they will likely be less monstrous, but also harder to spot,” Professor Kipping mentioned.
“The first detections in any survey will generally be the weirdos. The big ones that are simply easiest to detect with our limited sensitivity.”
“Observations from other space telescopes, like Hubble, will be needed to verify the discovery, a process that could take years,” he added.
The discovery is described in a paper revealed within the journal Nature Astronomy.
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D. Kipping et al. An exomoon survey of 70 cool big exoplanets and the brand new candidate Kepler-1708 b-i. Nat Astron, revealed on-line January 13, 2022; doi: 10.1038/s41550-021-01539-1