KIC 8016431 Possible Unlisted Planet Candidate

KIC 8016431 in Kepler Q7 at Planet Hunters

Planet Hunters forum Talk member Tesh90 flagged this possible unlisted planet candidate transit in the Kepler Q7 light curve. A second transit was identified near BJD 1420.2  along with transit analysis by Hans Martin (Zoo3hans).

Comments by Planet Hunters forum Talk member Kian Jek: 

Here is the TAP run:

The transit curve fit:


The transit depth is 933 ppm with a duration of 15.07 hr. In order to make the orbital parameters consistent with the stellar data at MAST, I find that I get a better fit if the stellar radius is adjusted up to 0.89x Sol instead of 0.621, and the stellar mass set to 0.95x Sol. This is more reasonable for a 5671K Teff, and makes this closer to a Sol-like star.

If so, then we get a 2.79x (+/- 0.21) RE planet, orbiting at 1.624 (+/- 0.21) AU from the primary. The Teq is approx. 184K.

You can follow the thread on this planet at Planet Hunters forum Talk thread here.

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. 

KIC 7105691 Unlisted Detached Eclipsing Binary with Highly Eccentric Orbit

KIC 7105691 in Q16 at NEA

Planet Hunters Talk member  Blammo flagged this star in Q16. It is part of an unlisted detached eclipsing binary star system that has now shown up for the first time in sixteen quarters of the Kepler light curves. The reason is that it has a highly eccentric orbit. Here is what PH forumTalk member Kian Jek has to say:

This is a very eccentric eclipsing binary for sure, but is it the real EB? An examination of the FITS file shows tiny APOs:

However, the vector plotted out shows the flux centroid shifting towards the tiny unmarked star at 1 o'clock. What I think is happening here is that during the dimming of the target, the presence of the companion in the halo pixel is shifting the centroid towards itself.

Let's try and calculate the eccentricity of this EB. I use the following relation, found in p. 86 of Kallrath and Milone (2009) to determine the minimum eccentricity of this EB:

where P is the period, t1, t2 are the epochs of the primary and secondary eclipses, in this case, for delta t1,t2, we have 29.8d as the separation between these 2 eclipses. P is not known, but we can assume that it is >1386d. Entering these values into the equation, we get a minimum eccentricity of 0.75.
This is quite an eccentric orbit, but it is not the most extreme eccentricity for an EB in the Kepler data set. That honor belongs to KIC 9214712, which has an e_min of 0.85 (see Dong et al)

You can read more about this star at the PH Talk thread here.