Those Tricky Unlisted Eclipsing Binary Stars

One would think it would be easy finding unlisted eclipsing binary (UEB) star systems by visually examining the Kepler light curves at Planet Hunters and then comparing the star data with a published eclipsing binary stars catalog. Here is an example of a detached eclipsing binary that was flagged by Planet Hunters forum Talk members back in December of 2011 for KID 4586468:

In order to be placed with Planet Hunters UEB candidates three transits drops must be observed through the quarters. The third transit drop was identified in Q9. All looks well except that this star is not part of an eclipsing binary star system. The real UEB is associated with KID 4586482.

Kian Jek:

APOs seen and vector plotted below. Contaminated by star #2, KID 4586482, which is the actual eclipsing binary  (an unlisted eclipsing binary) with a period of 623d.






You can follow the real eclipsing binary star system here.


Often light curve contamination of stars by background eclipsing binaries (BGEB) form strange patterns that cue Planet Hunters members to dig deeper. This is the light curve for KID 5791875 posted in October of 2011:

Click here for more detailed view of visual cue- the vertical and spaced light bars.

The next step is to run a phased curve for the light curve looking for the tell that it is an EB. In this case the phased curve shows a rough, but good image for an over contact eclipsing binary (OCEB):

Data from NASA Exoplanet Archive.

Kian Jek:

This curve is extremely noisy and the eclipses are very shallow - after some processing and detrending, this is the best I can do:




With the rounded tops and sharper alternating minimas it certainly looks like an OC EB, but the depths of the minimas are just 0.04%. It's possible that this is due to flux dilution. There is a brighter star nearby which has no periodicity, in fact it is a pulsating giant:


 

Data from NASA SkyView

Veteran forum Talk member Daryll LaCourse completed the analysis using PYKE and identified the real OCEB as star #2:


Source appears to lie in the direction of star #2 (KIC 5791886):



FULL
Flipped and rotated:


KIC 5791886 has a Q4-Q9 light curve on record and is obviously an EB but does not appear to be slated for inclusion in the Prsa catalog as yet:

Kian Jek:

Wow, that's a nice find, Daryll. 5791886 is definitely the real EB here, it's not even in v3, so it must be a new UEB:



Very nice, clean phased curve with deep eclipses. Note how the period matches that of KID 5791875.

You can follow the UEB here.