Astronomers using data from NASA’s Kepler space telescope have discovered two new planets in the Kepler-160 planetary system. One of the new planets is the super-Earth-sized transiting world in the host star’s habitable zone.
An artist’s impression of a four-planet system. Image credit: Sci-News.com.
Kepler-160 is a Sun-like star located 3,141 light-years away in the constellation of Lyra.
Also known as KOI-456 and KIC 7269974, the star is 1.12 times bigger than our Sun and is just 1% more luminous.
In 2010, astronomers detected two massive transiting planets, Kepler-160b and c, in very close orbits around the star.
Kepler-160b has a radius of 1.7 times that of the Earth and is in a 4.3-day orbit, while Kepler-160c, with a radius of about 3.1 Earth radii, orbits the star with a period of 13.7 days.
“Their surface temperatures would certainly make them hotter than a baking oven and everything but hospitable for life as we know it,” said Max Planck Institute for Solar System Research astronomer René Heller and colleagues.
“But tiny variations in the orbital period of planet Kepler-160c gave scientists a signature of a third planet that had yet to be confirmed.”
In the new study, Dr. Heller and co-authors analyzed archival data from the Kepler space telescope.
“Our analysis suggests that Kepler-160 is orbited not by two but by a total of four planets,” Dr. Heller said.
“One of the two planets that we found is Kepler-160d, the previously suspected planet responsible for the distorted orbit of Kepler-160c.”
Kepler-160d is a non-transiting planet with a mass higher than Earth’s and an orbital period between about 5 and 50 days.
The fourth planet in the system, Kepler-160e (also designated KOI-456.04), is probably a transiting planet with a radius of 1.9 times that of the Earth and an orbital period of 378 days.
“Given its Sun-like host star, the very Earth-like orbital period results in a very Earth-like insolation from the star — both in terms of the amount of the light received and in terms of the light color,” Dr. Heller said.
“All things considered, Kepler-160e sits in a region of the habitable zone that is comparable to the Earth’s position around the Sun.”
“Kepler-160e is relatively large compared to many other planets that are considered potentially habitable,” he said.
“But it’s the combination of this less-than-double the size of the Earth planet and its solar type host star that make it so special and familiar.”
“If Kepler-160e has a mostly inert atmosphere with a mild Earth-like greenhouse effect, then its surface temperature would be 5 degrees Celsius on average, which is about 10 degrees lower than the Earth’s mean global temperature.”
The discovery is described in paper published in the journal Astronomy & Astrophysics.
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René Heller et al. 2020. Transit least-squares survey III. A 1.9 R⊕ transit candidate in the habitable zone of Kepler-160 and a nontransiting planet characterized by transit-timing variations. A&A 638, A10; doi: 10.1051/0004-6361/201936929
