The Tenth PlanetHunters Habitable Zone Candidate

Another potential exoplanet orbiting in the habitable zone of its host star has been identified during a review of Quarter 5 light curves on PlanetHunters, this time around a G type star. The Kepler Input Catalog lists a radius of .8x Sol and a Teff of 5586(K) for this 13.9 Kmag target, designated as 4820550. The uncorrected light curve exhibits a fair degree of variability but so far in the public data set a total of four transits are found in Quarters 3, 5, 7 and 9 respectively. The period of these events is 202 days.

Some preliminary investigation indicates no obvious offsets, and KIC 4820550 does not appear to be included in the current Kepler Object of Interest catalog, nor does it appear in the official False Positive list.

The light curve before and after detrending to remove the stellar variability and trending:

To confirm this exoplanet candidate an important host of confirmation checks would need to be performed, including advanced screening for close background / foreground binaries and spectroscopic follow-up of the host star, but initial characterization is encouraging and shows this target may indeed reside inside the habitable zone where liquid water states could exist. The potential radius would rank this exoplanet slightly above that of the Neptune, placing it well outside the Super-Earth regime. Atmospheric colors and distribution in the header graphic were chosen arbitrarily; it's interesting to speculate if this body originally formed further out as an Ice Giant similar to the pair in our own solar system, and has since migrated inwards to its current position.

"Based on the plot, I have a transit depth of 2500ppm and duration of 4.56 hr. This works out to a planet with radius 4.4x RE and a somewhat high impact parameter of 0.86. It orbits the primary at a distance of 0.62 to 0.65AU and has a Teq of 273 to 280K, putting it in the HZ!"  -Kianjin
Source

This candidate increases the PH list of potential habitable zone targets to total of ten!