We are pleased to announce the submission of Planet Hunters VI: The First Kepler Seven Planet Candidate to the Astronomical Journal for peer review (The current version of the paper can be found online here ).
The most exciting result involves KOI-351, a system with six known planet candidates identified by the Kepler team, two of which had also been independently discovered by Planet Hunters before the Kepler identification. We have identified a seventh candidate, marking KOI-351 as the first Kepler seven planet system. While we cannot yet confirm the candidates in KOI-351, gravitational interactions between the planet candidates overwhelmingly point to their planetary nature. It is also known that false positives in multiple candidate systems are extremely rare. All of this together makes KOI-351 the strongest case for the first seven planet system known (apart from our own Solar System, of course!) The new planet is the fifth furthest from its parent star, orbiting with a period of nearly 125 days. With a radius of 2.8 times that of the Earth (+/- 1.1) it fits snugly into a family that now includes two roughly Earth sized worlds, three ‘super-Earths’ and two larger bodies.
In total, we announce the discovery of 14 planet candidates, all of which were identified by volunteers through the Planet Hunters Talk page. Of these, eight reside in their host star’s habitable zone, but none of them approach Earth or super-Earth size. Additionally, five of these new candidates met the requirements to have been detected by the Kepler team’s automated Transit Planet Search algorithm, but were undetected, including KOI-351.07, the newly discovered seventh candidate.
We look forward to the peer-review process for the Planet Hunters VI. We will include the names of the first identifiers in the final version of the paper. The Planet Hunters team continues on other exciting papers currently in the works. Thanks to all the Planet Hunters who have participated in this great project. We could not have done it without your help.
Post by Joey Schmitt, lead author on the new paper. Joey is a graduate student in the astronomy department at Yale University, where he is working with the exoplanet group led by Debra Fischer.