KEPLER-68: THREE PLANETS, ONE WITH A DENSITY BETWEEN THAT OF EARTH AND ICE GIANTS

Journal Article · Wed Mar 20 00:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/766/1/40· OSTI ID:22167573

Gilliland, Ronald L. ^[1]; Marcy, Geoffrey W.; Isaacson, Howard ^[2]; Rowe, Jason F.; Henze, Christopher E.; Lissauer, Jack J. ^[3]; Rogers, Leslie ^[4]; Torres, Guillermo; Fressin, Francois; Desert, Jean-Michel ^[5]; Lopez, Eric D. ^[6]; Buchhave, Lars A. ^[7]; Christensen-Dalsgaard, Jorgen; Handberg, Rasmus ^[8]; Jenkins, Jon M. ^[9]; Chaplin, William J.; Elsworth, Yvonne ^[10]; Basu, Sarbani ^[11]; Metcalfe, Travis S. ^[12]; Hekker, Saskia ^[13] ; others, and

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1. Department of Astronomy, and Center for Exoplanets and Habitable Worlds, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States)
2. Department of Astronomy, University of California, Berkeley, CA 94720 (United States)
3. NASA Ames Research Center, Moffett Field, CA 94035 (United States)
4. California Institute of Technology, Pasadena, CA 91125 (United States)
5. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
6. University of California, Santa Cruz, CA 95064 (United States)
7. Niels Bohr Institute, Copenhagen University (Denmark)
8. Stellar Astrophysics Centre, Department of Physics and Astronomy, DK-8000 Aarhus C (Denmark)
9. SETI Institute/NASA Ames Research Center, Moffett Field, CA 94035 (United States)
10. School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)
11. Department of Astronomy, Yale University, 260 Whitney Ave., New Haven, CT 06511 (United States)
12. White Dwarf Research Corporation, Boulder, CO 80301 (United States)
13. Astronomical Institute Anton Pannekoek, University of Amsterdam, 1098 XH Amsterdam, Science Park 904 (Netherlands)

NASA's Kepler Mission has revealed two transiting planets orbiting Kepler-68. Follow-up Doppler measurements have established the mass of the innermost planet and revealed a third Jovian-mass planet orbiting beyond the two transiting planets. Kepler-68b, in a 5.4 day orbit, has M{sub P}=8.3{sup +2.2}{sub -2.4} M{sub Circled-Plus }, R{sub P}=2.31{sup +0.06}{sub -0.09} R{sub Circled-Plus }, and {rho}{sub P}=3.32{sup +0.86}{sub -0.98} g cm{sup -3}, giving Kepler-68b a density intermediate between that of the ice giants and Earth. Kepler-68c is Earth-sized, with a radius R{sub P}=0.953{sup +0.037}{sub -0.042} R{sub Circled-Plus} and transits on a 9.6 day orbit; validation of Kepler-68c posed unique challenges. Kepler-68d has an orbital period of 580 {+-} 15 days and a minimum mass of M{sub P}sin i = 0.947 {+-} 0.035M{sub J} . Power spectra of the Kepler photometry at one minute cadence exhibit a rich and strong set of asteroseismic pulsation modes enabling detailed analysis of the stellar interior. Spectroscopy of the star coupled with asteroseismic modeling of the multiple pulsation modes yield precise measurements of stellar properties, notably T{sub eff} = 5793 {+-} 74 K, M{sub *} = 1.079 {+-} 0.051 M{sub Sun }, R{sub *} = 1.243 {+-} 0.019 R{sub Sun }, and {rho}{sub *} = 0.7903 {+-} 0.0054 g cm{sup -3}, all measured with fractional uncertainties of only a few percent. Models of Kepler-68b suggest that it is likely composed of rock and water, or has a H and He envelope to yield its density {approx}3 g cm{sup -3}.

• OSTI ID: 22167573
• Journal Information: Astrophysical Journal, Vol. 766, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
DENSITY
GIANT STARS
NASA
ORBITS
PHOTOMETRY
PLANETS
PULSATIONS
ROCKS
SIMULATION
SPECTRA
SPECTROSCOPY
VALIDATION
WATER