Dr. Manuel Perger, a postdoctoral researcher at Spain’s Institute of Space Sciences (IEEC-CSIC), and colleagues have discovered a ‘super-Earth’ exoplanet orbiting a low-mass star 55 light-years from the Sun.
This artist’s concept shows a super-Earth-size exoplanet. Image credit: NASA / JPL-Caltech.
Designated Gliese 3942b, the newfound alien world is about 7.1 times as massive as the Earth.
Its host star, Gliese 3942 (also known as GJ 3942, HIP 79126 or 2MASS J16090309+5256379), is a low-mass star with spectral type M0, located in the constellation of Draco.
Gliese 3942b orbits the star once every 6.9 days at a distance of only 0.06 AU (astronomical units).
Dr. Perger and co-authors estimate the planet’s temperature to be about 600 degrees Fahrenheit (317 degrees Celsius, or 590 Kelvin).
Gliese 3942b was detected using the High Accuracy Radial velocity Planet Searcher for the Northern hemisphere (HARPS-N) instrument on the 3.58-m Telescopio Nazionale Galileo in La Palma, Spain.
“We analyzed 145 spectroscopic HARPS-N observations of Gliese 3942 taken over the past five years and additional photometry to disentangle stellar activity effects from genuine Doppler signals as a result of the orbital motion of the star around the common barycenter with its planet,” the astronomers said.
“We identified the rotational period of the star at 16.3 days and discovered a new super-Earth, Gliese 3942b, with an orbital period of 6.9 days and a minimum mass of 7.1 Earths.”
According to the team, there is a periodic signal that hints a second planet, Gliese 3942c, could be hiding in the data.
“An additional signal in the periodogram of the residuals is present but we cannot claim it to be related to a second planet with sufficient significance at this point,” the researchers said.
“If confirmed, such planet candidate would have a minimum mass of 6.3 times that of the Earth, an equilibrium temperature of 468 degrees Fahrenheit (242 degrees Celsius, or 515 Kelvin), and a period of 10.4 days, which might indicate a 3:2 mean-motion resonance with the inner planet.”
“The possibility of additional planets in the Gliese 3942 system, likely in a near-resonant chain, is tantalizing but not confirmed by our analysis and thus remains open,” they added.
A paper describing the discovery will appear in the journal Astronomy & Astrophysics and is now available online at arXiv.org.
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M. Perger et al. 2017. HADES RV Programme with HARPS-N at TNG VI. GJ 3942 b behind dominant activity signals. A&A, in press; arXiv: 1709.06851
