KEPLER-20: A SUN-LIKE STAR WITH THREE SUB-NEPTUNE EXOPLANETS AND TWO EARTH-SIZE CANDIDATES

被引：91

作者：

Gautier, Thomas N., III ^{[1
]}

Charbonneau, David ^{[2
]}

Rowe, Jason F. ^{[3
]}

Marcy, Geoffrey W. ^{[4
]}

Isaacson, Howard ^{[4
]}

Torres, Guillermo ^{[2
]}

Fressin, Francois ^{[2
]}

Rogers, Leslie A. ^{[5
]}

Desert, Jean-Michel ^{[2
]}

Buchhave, Lars A. ^{[6
,7
]}

Latham, David W. ^{[2
]}

Quinn, Samuel N. ^{[2
]}

Ciardi, David R. ^{[8
]}

Fabrycky, Daniel C. ^{[9
]}

Ford, Eric B. ^{[10
]}

Gilliland, Ronald L. ^{[11
]}

Walkowicz, Lucianne M. ^{[12
]}

Bryson, Stephen T. ^{[3
]}

Cochran, William D. ^{[13
]}

Endl, Michael ^{[13
]}

Fischer, Debra A. ^{[14
]}

Howell, Steve B. ^{[3
]}

Horch, Elliott P. ^{[15
]}

Barclay, Thomas ^{[16
]}

Batalha, Natalie ^{[17
]}

Borucki, William J. ^{[3
]}

Christiansen, Jessie L. ^{[3
]}

Geary, John C. ^{[2
]}

Henze, Christopher E. ^{[3
]}

Holman, Matthew J. ^{[2
]}

Ibrahim, Khadeejah ^{[3
]}

Jenkins, Jon M. ^{[18
]}

Kinemuchi, Karen ^{[16
]}

Koch, David G. ^{[3
]}

Lissauer, Jack J. ^{[3
]}

Sanderfer, Dwight T. ^{[3
]}

Sasselov, Dimitar D. ^{[2
]}

Seager, Sara ^{[5
]}

Silverio, Kathryn ^{[4
]}

Smith, Jeffrey C. ^{[18
]}

Still, Martin ^{[16
]}

Stumpe, Martin C. ^{[18
]}

Tenenbaum, Peter ^{[18
]}

Van Cleve, Jeffrey ^{[18
]}

机构：

[1] CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA

[2] Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA

[3] NASA, Ames Res Ctr, Moffett Field, CA 94035 USA

[4] Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

[5] MIT, Dept Phys, Cambridge, MA 02139 USA

[6] Univ Copenhagen, Niels Bohr Inst, DK-2100 Copenhagen, Denmark

[7] Univ Copenhagen, Ctr Star & Planet Format, Nat Hist Museum Denmark, DK-1350 Copenhagen, Denmark

[8] CALTECH, NASA Exoplanet Sci Inst, Pasadena, CA 91125 USA

[9] Univ Calif Santa Cruz, Dept Astron & Astrophys, Santa Cruz, CA 95064 USA

[10] Univ Florida, Dept Astron, Gainesville, FL 32111 USA

[11] Penn State Univ, Dept Astron, Davey Lab 525, University Pk, PA 16802 USA

[12] Princeton Univ, Dept Astrophys Sci, Princeton, NJ 08544 USA

[13] Univ Texas Austin, McDonald Observ, Austin, TX 78712 USA

[14] Yale Univ, Dept Astron, New Haven, CT 06511 USA

[15] So Connecticut State Univ, Dept Phys, New Haven, CT 06515 USA

[16] NASA, Ames Res Ctr, Bay Area Environm Res Inst, Moffett Field, CA 94035 USA

[17] San Jose State Univ, Dept Phys & Astron, San Jose, CA 95192 USA

[18] NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA

来源：

ASTROPHYSICAL JOURNAL | 2012年 / 749卷 / 01期

关键词：

eclipses; planetary systems; stars:; individual; (Kepler-20; KIC; 6850504; 2MASS J19104752+4220194); TRANSITING PLANET; ADAPTIVE OPTICS; PHOTOMETRIC VARIABILITY; INITIAL CHARACTERISTICS; BLEND SCENARIOS; INFRARED CAMERA; Y-2; ISOCHRONES; WARM-SPITZER; LIGHT CURVES; TARGET STARS;

D O I：

10.1088/0004-637X/749/1/15

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present the discovery of the Kepler-20 planetary system, which we initially identified through the detection of five distinct periodic transit signals in the Kepler light curve of the host star 2MASS J19104752+4220194. From high-resolution spectroscopy of the star, we find a stellar effective temperature T-eff = 5455 +/- 100 K, a metallicity of [Fe/H] = 0.01 +/- 0.04, and a surface gravity of log g = 4.4 +/- 0.1. We combine these estimates with an estimate of the stellar density derived from the transit light curves to deduce a stellar mass of M-* = 0.912 +/- 0.034M(circle dot) and a stellar radius of R-* = 0.944(-0.095)(+0.060) R-circle dot. For three of the transit signals, we demonstrate that our results strongly disfavor the possibility that these result from astrophysical false positives. We accomplish this by first identifying the subset of stellar blends that reproduce the precise shape of the light curve and then using the constraints on the presence of additional stars from high angular resolution imaging, photometric colors, and the absence of a secondary component in our spectroscopic observations. We conclude that the planetary scenario is more likely than that of an astrophysical false positive by a factor of 2x10(5) (Kepler-20b), 1x10(5) (Kepler-20c), and 1.1x10(3) (Kepler-20d), sufficient to validate these objects as planetary companions. For Kepler-20c and Kepler-20d, the blend scenario is independently disfavored by the achromaticity of the transit: from Spitzer data gathered at 4.5 mu m, we infer a ratio of the planetary to stellar radii of 0.075 +/- 0.015 (Kepler-20c) and 0.065 +/- 0.011 (Kepler-20d), consistent with each of the depths measured in the Kepler optical bandpass. We determine the orbital periods and physical radii of the three confirmed planets to be 3.70 days and 1.91(-0.21)(+0.12) R-circle plus for Kepler-20b, 10.85 days and 3.07(-0.31)(+0.20) R-circle plus for Kepler-20c, and 77.61 days and 2.75(-0.30)(+0.17) R-circle plus for Kepler-20d. From multi-epoch radial velocities, we determine the masses of Kepler-20b and Kepler-20c to be 8.7 +/- 2.2M(circle plus) and 16.1 +/- 3.5M(circle plus), respectively, and we place an upper limit on the mass of Kepler-20d of 20.1M(circle plus) (2 sigma).

引用

页数：19

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