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PH2 b Paper Accepted

Today’s post is from Ji Wang. Ji is a post-doctoral associate working with Planet Hunters at Yale University. He obtained his PhD at the University of Florida in 2012. He is interested in exoplanet detection and characterization, statistics of exoplanets and its link to planet formation and evolution.

We are delighted to announce that the discovery paper of PH2 b is officially accepted and published on Astrophysical Journal. The link to the paper can be found here. PH 2b has been assigned with a Kepler number: Kepler-86b. PH2 b is a Jupiter-sized planet in the habitable zone of a solar-like star. Its radius is ten times of the Earth radii and it finishes one round trip around its host star every 282.5 days. PH2 b has the forth longest orbital period among Kepler detected planets, and it has the largest radius among all confirmed Kepler planets with periods longer than 100 days.

Over the past nine months, we have been working on the follow-up observations for PH2 b. From June 3rd 2013 to June 25th 2013, we obtained 4 data points of high-precision radial velocities using the Keck HIRES spectrograph. These observations allow us to rule out the possibility of false positives such as an eclipsing binary and a brown dwarf at a confidence of 96% and 80%, respectively. More radial velocity measurements in the future will allow us to precisely determine the mass of PH2 b.

Along with PH2 b, we have also announced 42 plant candidates identified by Planet Hunters. Most of them have orbital periods longer than 100 days and 20 of them are potentially located in the habitable zone. Our discoveries nearly double the number of previously known planets in the habitable zone and provide a sample of planet candidates for the study of planet formation and evolution at the habitable zone distances. Most of the planet candidates are larger than the radius of Neptune, they may not be habitable by themselves because of a lack of a rocky surface for life to form and evolve. However, satellites around them, analogs of moons around Saturn and Jupiter, may harbor life in a similar way as depicted in the movie of Avatar. Our discoveries are therefore suitable for the search for exo-moons, which is a frontier in the exoplanet research. As we are writing this blog, we already know that other groups are using the planet candidates in our paper to study the interior structure of gas giant planets and to conduct follow-up observations to confirm their planet nature. The race is on, but we are so glad that the Planet Hunters’ work has drawn so much attention across the community.

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