Most of us are used to the (usually) gradually changing seasons here on Earth, but astronomers have found an exoplanet where the changes are much more rapid and unpredictable because the planet wobbles like a toy top. The new discovery was announced yesterday, February 4, by scientists from the Kepler space telescope mission.
The planet, Kepler 413-b, orbits a pair of stars 2,300 light-years away in the constellation Cygnus. It orbits its stars, an orange dwarf and a red dwarf, every 66 days. What's unusual is that the planet wobbles wildly on its spin axis, which can vary by up to 30 degrees every 11 years. That's pretty extreme compared to Earth, which shifts its axis by only 23.5 degrees over 26,000 years.
This variation makes it harder to track the planet's orbit, since Kepler studies exoplanets by watching their transits across the front of their stars as views from Earth. Because of the wobbling, the planet isn't always visible as a transit.
"Looking at the Kepler data over the course of 1,500 days, we saw three transits in the first 180 days - one transit every 66 days - then we had 800 days with no transits at all. After that, we saw five more transits in a row," said Veselin Kostov, principal investigator and affiliated with the Space Telescope Science Institute and Johns Hopkins University in Baltimore, Md.
Peter McCullough, a team member with the Space Telescope Science Institute and Johns Hopkins University, adds:
"Presumably there are planets out there like this one that we're not seeing because we're in the unfavourable period. And that's one of the things that Veselin is researching: Is there a silent majority of things that we're not seeing?"
As for habitability, Kepler 413-b isn't a likely candidate, as it is a super-Neptune sized gas giant which orbits close to its two stars and is therefore much too hot.
Although Kepler is now non-functioning due to mechanical problems (with a possible modified secondary mission now being planned), there is still a lot of data yet to sift through and astronomers expect to still find many more exoplanets and maybe even exomoons.
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