J/AJ/161/231 A list of ∼330000 stars Kepler missed (Wolniewicz+, 2021)
The stars Kepler missed: investigating the Kepler target selection function
using Gaia DR2.
Wolniewicz L.M., Berger T.A., Huber D.
<Astron. J., 161, 231-231 (2021)>
=2021AJ....161..231W 2021AJ....161..231W (SIMBAD/NED BibCode)
ADC_Keywords: Stars, giant; Stars, dwarfs; Optical; Stars, diameters;
Cross identifications; Effective temperatures; Radial velocities
Keywords: Astronomy databases; Astronomy data analysis; Multiple stars
Exoplanet astronomy
Abstract:
The Kepler Mission revolutionized exoplanet science and stellar
astrophysics by obtaining highly precise photometry of over 200000
stars over 4yr. A critical piece of information to exploit Kepler data
is its selection function, since all targets had to be selected from a
sample of half a million stars on the Kepler CCDs using limited
information. Here we use Gaia DR2 to reconstruct the Kepler selection
function and explore possible biases with respect to evolutionary
state, stellar multiplicity, and kinematics. We find that the Kepler
target selection is nearly complete for stars brighter than Kp<14mag
and was effective at selecting main-sequence stars, with the fraction
of observed stars decreasing from 95% to 60% between 14<Kp<16mag. We
find that the observed fraction for subgiant stars is only 10% lower,
confirming that a significant number of subgiants selected for
observation were believed to be main-sequence stars. Conversely we
find a strong selection bias against low-luminosity red giant stars
(R∼3-5R☉, Teff∼5500K), dropping from 90% at Kp=14mag to below
30% at Kp=16mag, confirming that the target selection was efficient at
distinguishing dwarfs from giants. We compare the Gaia Re-normalized
Unit Weight Error (RUWE) values of the observed and nonobserved
main-sequence stars and find a difference in elevated (>1.2) RUWE
values at ~σ significance, suggesting that the Kepler target
selection shows some bias against either close or wide binaries. We
furthermore use the Gaia proper motions to show that the Kepler
selection function was unbiased with respect to kinematics.
Description:
In this paper we have analyzed the Kepler mission's target selection
function by using Gaia DR2 as the ground truth to characterize the
∼500000 stars that Kepler could have observed, and compared this
population to the sample of ∼200000 stars that were selected for
observations.
We started with a subset of 2.4million targets within the KIC that are
located in the Kepler field of view, which we downloaded from the
Mikulski Archive for Space Telescopes (MAST). As a first step, we
cross-matched the KIC with Gaia DR2 to obtain Gaia information for
each star in the KIC. To do this, we used the Centre de Donnees
astronomiques de Strasbourg (CDS) cross-match.
We conducted a positional match with a matching radius of 5", because
the astrometric offsets between the KIC and Gaia have not been well
characterized. We removed duplicates by only selecting the Kepler and
Gaia ID associated with the most similar magnitudes in the Kepler
passband Kp and Gaia passband.
We then extracted Gaia Re-normalized unit weight error (RUWE) values
for all sources.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 74 328196 Stellar properties of all stars that fall on
the Kepler CCDs
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/AJ/142/112 : KIC photometric calibration (Brown+, 2011)
J/A+A/546/A10 : Multiplicity in transiting planet-host stars (Lillo-Box+, 2012)
J/ApJ/753/90 : Stellar parameters of K5 & later type Kepler stars (Mann+, 2012)
J/ApJ/767/95 : Improved stellar parameters smallest KIC stars (Dressing+, 2013)
J/ApJ/771/107 : Spectroscopy of faint KOI stars (Everett+, 2013)
J/ApJ/791/35 : Detection 715 Kepler planet candidates host stars (Law+, 2014)
J/ApJ/795/64 : Catalog of exoplanet physical parameters (Foreman-Mackey+, 2014)
J/ApJS/211/2 : Revised stellar properties Q1-16 Kepler targets (Huber+, 2014)
J/ApJS/215/19 : APOKASC catalog of Kepler red giants (Pinsonneault+, 2014)
J/ApJ/809/8 : Terrestrial planet occurrence rates for KOI stars (Burke+, 2015)
J/AJ/152/8 : Impact of stellar mult. on planetary systems I. (Kraus+, 2016)
J/AJ/152/18 : Robo-AO Kepler planetary candidate survey. II. (Baranec+, 2016)
J/AJ/153/71 : Kepler follow-up observation program. I. Imaging (Furlan+, 2017)
J/AJ/155/161 : Stars nearby Robo-AO Kepler planetary candidates (Ziegler+,2018)
J/AJ/156/292 : Effect of close companions on exoplanetary radii (Teske+, 2018)
J/ApJS/235/38 : Kepler planetary cand. VIII. DR25 reliability (Thompson+, 2018)
J/ApJ/866/99 : Revised radii KIC stars & planets using Gaia DR2 (Berger+, 2018)
J/MNRAS/474/4322 : Orbital parameters of 341 new binaries (Murphy+, 2018)
J/AJ/158/109 : Occurrence rates of planets orbiting FGK stars (Hsu+, 2019)
J/MNRAS/499/4114 : Properties of LMC star clusters (Gatto+, 2020)
http://archive.stsci.edu/ : Mikulski Archive for Space Telecsope homepage
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- KIC Kepler Input Catalog identifier
10- 28 I19 --- Gaia Gaia DR2 identifier
30 I1 --- Obs [0/1] Observation flag (1)
32 I1 --- Host [0/1] Host flag (2)
34- 38 F5.2 mag Kmag [4.49/16] Apparent Kepler magnitude
40- 44 I5 K Teff [2469/19297] Effective temperature
46- 52 F7.3 Rsun Rad [0.14/796] Radius
54- 57 I4 pc Dist [4/9297] Distance
59- 64 F6.3 --- RUWE [0.63/68.7]? Gaia Re-normalized Unit Weight Error
66- 72 F7.3 km/s RVel [0.06/575] Radial velocity
74 I1 --- Class [0/2] Evolutionary state (3)
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Note (1): Flags as follows:
1 = observed; 177889 occurrences
0 = not observed; 15307 occurrences
Note (2): Flags as follows:
1 = host star; 3196 occurrences
0 = not a host star; 325000 occurrences
Note (3): State as follows:
0 = Main Sequence; 204644 occurrences
1 = Sub Giant; 62239 occurrences
2 = Red Giant; 61313 occurrences
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 05-Jul-2021