Keck confirms: Armchair astronomers find planet in four-star system
A joint effort of citizen scientists and professional astronomers at W.M. Keck Observatory in Hawaii has led to the first reported case of a Tatooine-like planet orbiting twin suns that in turn is orbited by a second distant pair of stars. Aided by volunteers using the Planethunters.org website, a Yale-led international team of astronomers using Keck's 10-meter telescope identified and confirmed discovery of the phenomenon, called a circumbinary planet in a four-star system. Read more
Title: A Gas Giant Circumbinary Planet Transiting an Evolved F Star Primary of the Eclipsing Binary Star KIC 4862625 and the Independent Discovery and Characterization of the two transiting planets in the Kepler-47 System Authors: Veselin B. Kostov, Peter McCullough, Tobias Hinse, Zlatan Tsvetanov, Guillaume Hébrard, Rodrigo Díaz, Magali Deleuil, Jeff A. Valenti
We report the discovery of a transiting, gas giant circumbinary planet orbiting the eclipsing binary KIC 4862625 and describe our independent discovery of the two transiting planets orbiting Kepler-47 (Orosz et al. 2012). We describe a simple and semi-automated procedure for identifying individual transits in light curves and present our follow-up measurements of the two circumbinary systems. For the KIC 4862625 system, the 0.49±0.018 RJup radius planet revolves every ~138 days and occults the 1.14±0.14 solar masses, 1.59±0.06 solar radii F8 IV subgiant primary star producing aperiodic transits of variable durations commensurate with the configuration of the eclipsing binary star. Our best-fit model indicates the orbit has a semi-major axis of 0.56 AU and is slightly eccentric, e=0.1. For the Kepler-47 system, we confirm the results of Orosz et al. (2012). Modulations in the radial velocity of KIC 4862625A are measured both spectroscopically and photometrically, i.e. via Doppler boosting, and produce similar results.
Astronomers have found a planet whose skies are illuminated by four different suns - the first known of its type. The distant world orbits one pair of stars and has a second stellar pair revolving around it. It remains a mystery how the Neptune-like world avoids being pulled apart by the gravitational forces generated its four stars. Read more
Title: Planet Hunters: A Transiting Circumbinary Planet in a Quadruple Star System Authors: Megan E. Schwamb, Jerome A. Orosz, Joshua A. Carter, William F. Welsh, Debra A. Fischer, Guillermo Torres, Andrew W. Howard, Justin R. Crepp, William C. Keel, Chris J. Lintott, Nathan A. Kaib, Dirk Terrell, Robert Gagliano, Kian J. Jek, Michael Parrish, Arfon M. Smith, Stuart Lynn, Robert J. Simpson, Matthew J. Giguere, Kevin Schawinski
We report the discovery and confirmation of a transiting circumbinary planet (PH1) around KIC 4862625, an eclipsing binary in the Kepler field. The planet was discovered by volunteers searching the first six Quarters of publicly available Kepler data as part of the Planet Hunters citizen science project. Transits of the planet across the larger and brighter of the eclipsing stars are detectable by visual inspection every ~137 days, with seven transits identified in Quarters 1-11. The physical and orbital parameters of both the host stars and planet were obtained via a photometric-dynamical model, simultaneously fitting both the measured radial velocities and the Kepler light curve of KIC 4862625.The 6.18 ± 0.17 Earth radii planet orbits outside the 20-day orbit of an eclipsing binary consisting of an F dwarf (1.734 ± 0.044 Solar radii, 1.528 ± 0.087 Solar masses) and M dwarf (0.378 ± 0 0.023 Solar radii, 0.408 ± 0.024 solar masses). 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, PH1 is well within the planetary regime. Outside the planet's orbit, at ~1000 AU, a previously unknown visual binary has been identified that is bound to the planetary system, making this the first known case of a quadruple star system with a transiting planet.