A New Potential Habitable Zone Exo for Kepler

The preliminary characterization of another long period exoplanet within the Habitable Zone of its host star has become possible recently by way of a third transit spotted in public Quarter 7 data, around target KIC 9958387.

This star is listed in the KIC catalog as a main sequence spectral type F just slightly larger than our own Sun, with a temperature of 6159(K) and an apparent visual magnitude of 13.5. The transits for this candidate were noted during manual searches by PH users and display a period of  237 days (with Transits 1 and 2 occurring in Quarter 2 and 4, respectively), if the aforementioned KIC values are accurate then combining them with the observed depth and duration should correspond to a body of roughly 5 times Earth radius and a Teq of 325 to 332K!

Significant pixel offsets that might indicate a contaminating eclipsing binary do not seem readily apparent here and lend some more weight to this initial characterization, although further follow up is of course required.

With a possible radius of ~32 000km, this exoplanet certainly would not resemble Earth despite being at a comfortable distance from the F star; any rocky core is likely well swathed with a thick envelope of gases that could come in a wide range of compositions. But considering the potential HZ orbit, it's interesting to speculate if significant H20, organic molecules and other basics required by the sort of prokaryotes and extremophiles we recognize may be present there--or if there are also any accompanying exomoons!

This is a crude scale approximation to Earth below; the atmospheric colors and distribution are randomly generated.

Graphics courtesy of NEA, Sphere Builder & Kian Jek