1. History of Detection

The Kepler search volume, in the context of the Milky Way Galaxy. https://handwiki.org/wiki/index.php?curid=1438356

PH2 b was detected, along with 42 other planet candidates, in archival data from Kepler by the Planet Hunters project, in which human volunteers analyze the light curves of Kepler target stars, searching for planetary transit signals which may be missed by computer programs.^[1] Previous work by Planet Hunters helped to confirm the existence of PH1 b, a Neptune-mass planet within a four-star system.

All of the candidates in the second, including PH2 b, were identified by citizen scientists Abe J. Hoekstra, Thomas Lee Jacobs, Daryll LaCourse, Hans Martin Schwengler, Rafał Herszkowicz and Mike Chopin among others, with the help of Yale University astronomers.^[1] In addition to PH2 b itself, twenty other planet candidates were found which are located in the habitable zones of their host stars; however, these have a relatively high probability of spurious detection and may well come from non-planetary sources.^[1]

Although the planet's initial detection was made using Kepler data, PH2's stellar spectra, required to rule out background stars or faint companions with planets as sources for the observed transits, were collected using the HIRES instrument at the W. M. Keck Observatory.^[1] Results of observations confirmed the existence of PH2 b with "99.9 percent confidence."^[1][2]

2. Planetary System

PH2 is host to one confirmed planet, PH2 b, orbiting with a period of about 282 days, placing it and any possible moons in the habitable zone.^[2] The temperature in the upper atmosphere of the planet could range from 185 K (−88 °C; −127 °F) to 303 K (30 °C; 86 °F).^[1] A moon of PH2 b would likely have "a rocky core, plus a greenhouse atmosphere of some sort that could have liquid water on its surface" in the words of the researchers, thus further improving its prospects for habitability.^[2]