KEPLER-21b: A 1.6 REarth planet transiting the bright oscillating F subgiant star HD179070

Steve B. Howell, Jason F. Rowe, Stephen T. Bryson, Samuel N. Quinn, Geoffrey W. Marcy, Howard Isaacson, David R. Ciardi, William J. Chaplin, Travis S. Metcalfe, Mario J.P.F.G. Monteiro, Thierry Appourchaux, Sarbani Basu, Orlagh L. Creevey, Ronald L. Gilliland, Pierre Olivier Quirion, Denis Stello, Hans Kjeldsen, Jörgen Christensen-Dalsgaard, Yvonne Elsworth, Rafael A. GarcíaGünter Houdek, Christoffer Karoff, Joanna Molenda-Akowicz, Michael J. Thompson, Graham A. Verner, Guillermo Torres, Francois Fressin, Justin R. Crepp, Elisabeth Adams, Andrea Dupree, Dimitar D. Sasselov, Courtney D. Dressing, William J. Borucki, David G. Koch, Jack J. Lissauer, David W. Latham, Lars A. Buchhave, Thomas N. Gautier, Mark Everett, Elliott Horch, Natalie M. Batalha, Edward W. Dunham, Paula Szkody, David R. Silva, Ken Mighell, Jay Holberg, Jerme Ballot, Timothy R. Bedding, Hans Bruntt, Tiago L. Campante, Rasmus Handberg, Saskia Hekker, Daniel Huber, Savita Mathur, Benoit Mosser, Clara Régulo, Timothy R. White, Jessie L. Christiansen, Christopher K. Middour, Michael R. Haas, Jennifer R. Hall, Jon M. Jenkins, Sean McCaulif, Michael N. Fanelli, Craig Kulesa, Don McCarthy, Christopher E. Henze

Research output: Contribution to journalArticlepeer-review

98 Scopus citations


We present Kepler observations of the bright (V = 8.3), oscillating star HD179070. The observations show transit-like events which reveal that the star is orbited every 2.8days by a small, 1.6 R Earth object. Seismic studies of HD179070 using short cadence Kepler observations show that HD179070 has a frequency-power spectrum consistent with solar-like oscillations that are acoustic p-modes. Asteroseismic analysis provides robust values for the mass and radius of HD179070, 1.34 ± 0.06 M and 1.86 ± 0.04 R , respectively, as well as yielding an age of 2.84 ± 0.34Gyr for this F5 subgiant. Together with ground-based follow-up observations, analysis of the Kepler light curves and image data, and blend scenario models, we conservatively show at the >99.7% confidence level (3σ) that the transit event is caused by a 1.64 0.04 R Earth exoplanet in a 2.785755 ± 0.000032day orbit. The exoplanet is only 0.04 AU away from the star and our spectroscopic observations provide an upper limit to its mass of ∼10 M Earth (2σ). HD179070 is the brightest exoplanet host star yet discovered by Kepler.

Original languageEnglish (US)
Article number123
JournalAstrophysical Journal
Issue number2
StatePublished - Feb 20 2012

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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