hot jupiter
March 11, 2016

New, less dense ‘hot Jupiter’ exoplanets discovered using Kepler data

Two newly-identified “hot Jupiter” exoplanets discovered using data from NASA's Kepler spacecraft during its second-generation K2 mission are less dense than our Jupiter, which could make them good candidates for in-depth, follow-up studies about their atmospheres.

According to UPI and reports, the two planets have been designated  EPIC210957318b and EPIC212110888b and were discovered using what is known as the radial velocity method, a technique that uses observations of Doppler shifts in a host star to find new worlds indirectly .

Lead researcher Rafael Brahm of the Pontifical Catholic University of Chile and his colleagues examined the signatures of these two exoplanets, each of which are approximately the same mass as Jupiter but orbit their suns at a much closer distance (hence the name “hot Jupiter”) and found that they passed in front of their stars around once every three to four days.

The transit properties encoded in their shadows’ signature, including the depths, the shapes, and the duration of their passage in front of their suns, indicate that both worlds are “strong Jovian planetary candidates,” the authors explained in a paper currently available online and which has been submitted to the Publications of the Astronomical Society of the Pacific.

Good candidates for follow-up research, the authors claim

While Jupiter orbits the sun at a distance of 5.2 astronomical units (AU) and takes 11.86 years to complete its journey, hot Jupiters are far closer (orbiting their host stars at distances of 0.015 AU to 0.5 AU) and typically taking less than 10 days to orbit their suns, UPI and said.

EPIC210957318b is the smaller of the two exoplanets, the study authors noted. It is 0.65 Jupiter masses in size, meaning that its mass is somewhere between that of Jupiter and Saturn. It orbits a sun-like star located 970 light-years from Earth, and takes 4.1 days to travel around the star.

The other planet, EPIC212110888b is larger (1.63 Jupiter masses) and hotter (it has an average surface temperature of between 932 and 1,430 degrees Celsius, compared to 584 to 939 degrees Celsius for EPIC210957318b). EPIC212110888b orbits a star that is larger than the sun, and is located 1,270 light-years away, Brahm’s team reported in their study.

Both planets have densities roughly half that of Jupiter’s, and  the physical and orbital properties of their systems are described as typical of those where other, similar exoplanets have been found, the scientists explained. The low densities of the planets make them prime candidates for follow-up studies, through which the researchers hope to learn more about their atmospheres.

“Both planets were validated probabilistically and confirmed via precision radial velocity (RV) measurements,” they wrote. “They have physical and orbital properties similar to the ones of the already uncovered population of hot Jupiters and are well-suited candidates for further orbital and atmospheric characterization via detailed follow-up observations.”


Image credit: Ricardo Cardoso Reis