Kepler Light Curve KIC 8681125 in Q16 at Planet Hunters
Planet Hunters forum Talk member Kugelbitz flagged this light curve in Kepler Quarter 16 that was subsequently analyzed by veteran Talk members as a viable 5.24 RE planet candidate with two known transits in Q10 and Q16.
Kian Jek:
The first new PC seen in a long time - and just goes to show there are still treasures hidden in the data set even almost a year after Kepler has stopped functioning and moved on to its next mission!
The problem with this target is that although it's situated near the center of the FOV, it lies at the extreme edge of the module, and it's only visible in two out of four of the CCD panels or channels. These correspond to the even quarters and so the odd quarter data are missing.
Because of these large data gaps, one can fit two possible periods to this PC, either 615d or 307.5d.
The two visible transits can be model-fitted to a 615d period transit exceptionally well (see the R2 statistic):
The transit can also be fitted to a 307d period, but this gave an anomalous a/R* of 187.7 vs 375; the latter value is more consistent with the stellar radius and orbital separation wrt period, so the 307d period can be ruled out.
The stellar radius appears to be slightly less than the MAST estimate, to give a Keplerian orbital parameter, approx. ~0.87x Rsol, so based on this, the planetary radius is ~5.24x RE. We will need ground-based follow-up observations to observe a third and confirming transit, this is possible now that we can construct an ephemeris, but it's still going to be challenging as this is a very faint Kp=15 star.You can follow this planet on Planet Hunters forum Talk here.
