An Earth Sized Planet Around a G Class Star Acting Like a Fast Ball

TRANSITS AND OCCULTATIONS OF AN EARTH-SIZED PLANET IN AN 8.5 hr ORBIT

Authors:

1. Roberto Sanchis-Ojeda (a)
2. Saul Rappaport (a)
3. Joshua N. Winn (a)
4. Alan Levine (b)
5. Michael C. Kotson (c)
6. David W. Latham (d)
7. Lars A. Buchhave (e,f)

Affiliations:

a. Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA

b. M.I.T. Kavli Institute for Astrophysics and Space Research, 70 Vassar St., Cambridge, MA 02139, USA

c. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA

d. Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA

e. Niels Bohr Institute, University of Copenhagen, Juliane Maries vej 30, DK-2100 Copenhagen, Denmark

f. Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen, Denmark

Abstract:

We report the discovery of an Earth-sized planet (1.16 ± 0.19 R ⊕) in an 8.5 hr orbit around a late G-type star (KIC 8435766, Kepler-xx). The object was identified in a search for short-period planets in the Kepler database and confirmed to be a transiting planet (as opposed to an eclipsing stellar system) through the absence of ellipsoidal light variations or substantial radial-velocity variations. The unusually short orbital period and the relative brightness of the host star (m Kep = 11.5) enable robust detections of the changing illumination of the visible hemisphere of the planet, as well as the occultations of the planet by the star. We interpret these signals as representing a combination of reflected and reprocessed light, with the highest planet dayside temperature in the range of 2300 K-3100 K. Follow-up spectroscopy combined with finer sampling photometric observations will further pin down the system parameters and may even yield the mass of the planet.