KIC 9396866 Possible Unlisted Planet Candidate in Habitable Zone

KIC 9396866 Q4 light curve at Planet Hunters

Planet Hunters forum Talk member Scienceweb flagged this possible unlisted planet candidate transit in the Kepler Q4 light curve. A second transit was identified near BJD 1342.5 along with transit analysis by Hans Martin (Zoo3hans).

Comments by Planet Hunters forum Talk member Kian Jek:

Here are the results of running a Mandel-Agol fit on the 2 transits.

From the fitted curve the depth is 290 ppm and duration is 25.2 hrs. The goodness of fit parameter, R2 is reasonable, at 0.59, and isn't too bad, given the circumstances. Since this is a Kp=12.59 star, the quality of the light curve could have been better, but even so, a 290 ppm transit does stand out quite clearly.

The problem is that MAST does not have stellar parameters for this star, but since we know the period, depth, duration and the Rp/R* and a/R* values derived from the transit fit we can make some guesses.The stellar primary is ~1.67x Sol and mass of ~1.23x Sol. The planetary radius is 2.98 (+/- 0.16) RE, orbiting at a distance of ~2 AU. The Teff of the star is not known, but an averaged guesstimate from the gr, J-K and G-K values gives something around 6000K. If so, then this is a possible HZ planet with a Teq of 236K. A little chilly, but this is actually warmer than Mars.

You can read more about this transit at Planet Hunters forum Talk here.