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Planet Hunters discovery: PH1b (Kepler-64b)

Excerpt from Planet Hunter Blog

...Last October [Planet Hunters] announced the discovery of PH1 – a four star planetary system hosting a circumbinary planet (PH1b). The transits were spotted by volunteers Robert Gagliano and Kian Jek on Talk. ...[the] paper “Planet Hunters: A Transiting Circumbinary Planet in a Quadruple Star System” has been officially accepted to Astrophysical Journal []. Congratulations to all involved. ...PH1b is our first confirmed exoplanet discovery, a milestone for Planet Hunters. The 6.18 Earth radii planet orbits outside the 20-day orbit of an eclipsing binary consisting of an F dwarf ( 1.734 x the Radius of the Sun) and M dwarf ( 0.378 x the Radius of the Sun). For the planet, we find an upper mass limit of 169 Earth masses (0.531 Jupiter masses) at the 99.7% confidence level. With a radius and mass less than that of Jupiter, PH1b is a bona fide planet. Not all planet candidates can be confirmed as we could with PH1b. Since PH1b is orbiting an eclipsing binary, we could use the fact that there are no changes in the timing of the stellar eclipses due to the planet to constrain PH1b’s mass. ...PH1b has been given officially a Kepler designation of Kepler-64b and added to the list of planets in the Kepler field. You can find out more about what the criteria for obtaining a Kepler # is [at]....

See full blog entry by Megan Schwamb

Image from discovery paper:

Kepler-64b light curve as viewed in Planet Hunters interface
Fig. 1.— Planetary transits in addition to binary-star eclipses identified by Planet Hunters volunteers in KIC 4862625 as viewed in the Planet Hunters interface.

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