J/ApJ/749/15 The Kepler-20 planetary system (Gautier+, 2012)
Kepler-20: a sun-like star with three Sub-Neptune exoplanets and
two Earth-size candidates.
Gautier III T.N., Charbonneau D., Rowe J.F., Marcy G.W., Isaacson H.,
Torres G., Fressin F., Rogers L.A., Desert J.-M., Buchhave L.A.,
Latham D.W., Quinn S.N., Ciardi D.R., Fabrycky D.C., Ford E.B.,
Gilliland R.L., Walkowicz L.M., Bryson S.T., Cochran W.D., Endl M.,
Fischer D.A., Howell S.B., Horch E.P., Barclay T., Batalha N.,
Borucki W.J., Christiansen J.L., Geary J.C., Henze C.E., Holman M.J.,
Ibrahim K., Jenkins J.M., Kinemuchi K., Koch D.G., Lissauer J.J.,
Sanderfer D.T., Sasselov D.D., Seager S., Silverio K., Smith J.C.,
Still M., Stumpe M.C., Tenenbaum P., Van Cleve J.
<Astrophys. J., 749, 15 (2012)>
=2012ApJ...749...15G 2012ApJ...749...15G
ADC_Keywords: Planets ; Stars, double and multiple
Keywords: eclipses - planetary systems -
stars: individual (Kepler-20, KIC 6850504, 2MASS J19104752+4220194)
Abstract:
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 Teff= 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±0.034 M☉and a stellar radius of
R* = 0.944+0.060-0.095R☉. For three of the transit
signals, we demonstrate that our results strongly disfavor the
possibility that these result from astrophysical false positives. We
determine the orbital periods and physical radii of the three
confirmed planets to be 3.70 days and 1.91+0.12-0.21R{earth} for
Kepler-20b, 10.85 days and 3.07+0.20-0.31R{earth} for
Kepler-20c, and 77.61 days and 2.75+0.17-0.30R{earth} for
Kepler-20d. From multi-epoch radial velocities, we determine the
masses of Kepler-20b and Kepler-20c to be 8.7±2.2 M{earth} and
16.1 ±3.5 M{earth}, respectively, and we place an upper limit on
the mass of Kepler-20d of 20.1 M{earth}(2σ).
Description:
Kepler observations of Kepler-20 commenced UT 2009 May 13 with Quarter
1 (Q1), and the Kepler data that we describe here extend through UT
2011 March 14, corresponding to the end of Quarter 8 (Q8), resulting
in near-continuous monitoring over a span of 22.4 months. The Kepler
bandpass spans 423-897nm (∼V+R), for which the response is greater
than 5%.
Objects:
-------------------------------------------------------
RA (2000) DE Designation(s)
-------------------------------------------------------
19 10 47.52 +42 20 19.3 Kepler-20 = GSC 03129-01902
-------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 73 5 Offsets between photocenter of transit signal
and Kepler-20
table9.dat 38 358 Transit times for Kepler-20
--------------------------------------------------------------------------------
See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
J/ApJS/204/24 : Kepler planetary candidates. III. (Batalha+, 2013)
J/ApJS/199/24 : The first three quarters of Kepler mission (Tenenbaum+, 2012)
J/AJ/144/42 : Infrared photometry of 90 KOIs (Adams+, 2012)
J/PASP/123/412 : Exoplanet Orbit Database (Wright+, 2011)
J/ApJS/197/8 : Kepler's cand. multiple transiting planets (Lissauer+, 2011)
J/ApJS/197/2 : Transit timing observations from Kepler. I. (Ford+, 2011)
J/ApJ/738/170 : False positive Kepler planet candidates (Morton+, 2011)
J/ApJ/736/L25 : Habitability of Kepler planetary cand. (Kaltenegger+, 2011)
http://archive.stsci.edu/kepler/ : MAST Kepler archive
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- ID Planet candidate designation (Kepler-NNa or
KOI-NN.NN)
12- 16 F5.3 arcsec CentP [0.02/0.73] PRF centroid (1)
18- 21 F4.2 arcsec e_CentP CentP uncertainty
23- 26 F4.2 --- SigP Significance (2)
28- 32 F5.3 arcsec CentF [0.07/3.07] Flux-weighted centroid (1)
34- 37 F4.2 arcsec e_CentF CentF uncertainty
39- 42 F4.2 --- SigF Significance (2)
44- 53 F10.7 d Per ? Orbital period (from table 2)
55- 63 F9.7 d E_Per ? Positive error on Per
65- 73 F9.7 d e_Per ? Negative error on Per
-------------------------------------------------------------------------------
Note (1): We use two methods to examine the Kepler pixel data to evaluate
the location of the photocenter and thus to search for astrophysical
false positives: (1) the direct measurement of the source location via
difference images, the pixel response function (PRF) centroid method,
and (2) the inference of the source location from photocenter motion
associated with the transits, the flux-weighted centroid method. In
principle both techniques are similarly accurate, but in practice the
flux-weighted centroid technique is more sensitive to noise for low
signal-to-noise ratio (S/N) transits. We use both techniques because
they are both subject to biases due to various systematics but respond
to those systematics in different ways. See section 2.3.
Note (2): Offset/uncertainty
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table9.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- ID Planet identifier
12- 14 I3 --- n [0/180] Transit number
16- 23 F8.4 d tn Barycentric Julian date of transit; BJD-2454900 (1)
25- 31 F7.4 d TTV [-0.074/0.072] Transit Timing Variation
33- 38 F6.4 d e_TTV The 1σ uncertainty in TTV
--------------------------------------------------------------------------------
Note (1): Best-fit linear ephemerides
Kepler-20b: tn = 67.50027 + n * 3.6961219
70.04: tn = 68.9336 + n * 6.098493
Kepler-20c: tn = 71.6076 + n * 10.85409
70.05: tn = 68.219 + n * 19.57706
Kepler-20d: tn = 97.7271 + n * 77.61184
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 07-Nov-2013