Amateur astronomers from the Habitable Exoplanet Hunting Project, the first international program coordinated by amateur astronomers to search for potentially habitable exoplanets, have announced the discovery of a new extrasolar planet candidate orbiting the red dwarf Gliese 3470. The detection was made using a telescope at the OKSky Observatory in Kiowa, Oklahoma.
An artist’s impression of the Gliese 3470 planetary system. Image credit: Sci-News.com.
Gliese 3470 is an M1.5-type star located 100 light-years away in the constellation of Cancer.
Also known as GJ 3470 or LP 424-4, the star has around half the mass and size of the Sun.
Astronomers had previously detected a Neptune-like exoplanet around Gliese 3470.
Named Gliese 3470b, it has a mass 13.9 times that of the Earth, a radius 4.4 times that of our planet, and an orbital period of just 3.3 days.
The newfound planet, Gliese 3470c, has a radius of 9.2 times that of Earth, making it a bit bigger that Saturn.
It has an orbital period of 66 days and resides in the habitable zone of the Gliese 3470 system.
“If confirmed, Gliese 3470c would be the first exoplanet totally discovered by amateur astronomers,” said OKSky Observatory astronomer Phillip Scott and colleagues.
The researchers detected three transits of Gliese 3470c: the first one on December 23, 2019, the second one on February 27, 2020, and the third one on May 3, 2020.
They also detected twelve other transits that could belong to different exoplanets, but they were not able to estimate any orbital period.
“Our candidate for Gliese 3470c still has to be confirmed by other professional observatories, but the diversity of potential transits we found suggests a high likelihood of existing more exoplanets in the system apart from Gliese 3470b,” they said.
A paper reporting the discovery was published online on the arXiv.org preprint server.
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Phillip Scott et al. 2020. GJ 3470 c: A Saturn-like Exoplanet Candidate in the Habitable Zone of GJ 3470. arXiv: 2007.07373
