J/ApJ/855/115 Lithium abundances of KOIs from CKS spectra (Berger+, 2018)
Identifying young Kepler planet host stars from Keck-HIRES spectra of lithium.
Berger T.A., Howard A.W., Boesgaard A.M.
<Astrophys. J., 855, 115 (2018)>
=2018ApJ...855..115B 2018ApJ...855..115B
ADC_Keywords: Abundances; Stars, double and multiple; Equivalent widths;
Exoplanets; Optical
Keywords: planetary systems ; stars: abundances
Abstract:
The lithium doublet at 6708Å provides an age diagnostic for main
sequence FGK dwarfs. We measured the abundance of lithium in 1305
stars with detected transiting planets from the Kepler mission using
high-resolution spectroscopy. Our catalog of lithium measurements from
this sample has a range of abundance from A(Li)=3.11±0.07 to an
upper limit of -0.84dex. For a magnitude-limited sample that comprises
960 of the 1305 stars, our Keck-HIRES spectra have a median
signal-to-noise ratio of 45 per pixel at ∼6700Å with spectral
resolution λ/Δλ=R=55000. We identify 80 young
stars that have A(Li) values greater than the Hyades at their
respective effective temperatures; these stars are younger than
∼650Myr, the approximate age of the Hyades. We then compare the
distribution of A(Li) with planet size, multiplicity, orbital period,
and insolation flux. We find larger planets preferentially in younger
systems, with an A-D two-sided test p-value=0.002, a>3σ
confidence that the older and younger planet samples do not come from
the same parent distribution. This is consistent with planet
inflation/photoevaporation at early ages. The other planet parameters
(Kepler planet multiplicity, orbital period, and insolation flux) are
uncorrelated with age.
Description:
One key follow-up survey of Kepler-discovered exoplanets is the
California Kepler Survey (CKS) (Petigura+ 2017, J/AJ/154/107), which
was proposed to measure precise stellar parameters (Teff, logg,
[Fe/H], vsini) by using local thermodynamic equilibrium (LTE) modeling
of Keck-HIRES spectra of ∼1000 Kepler FGK stars.
Most spectra have signal-to-noise ratios (S/Ns) of ∼45 per pixel, or
∼90 per resolution element at 6700Å, with a resolution R=55000 and
wavelength coverage from 3642-7990Å. S/N ranges from ∼5 to ∼200.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 78 1301 Pipeline results for Kepler planet host stars
table2.dat 55 80 Stars younger than the Hyades
table3.dat 90 86 Planets younger than the Hyades
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
J/A+A/331/81 : Hyades membership (Perryman+ 1998)
J/ApJ/724/154 : Lithium abundances in stars with planets (Ghezzi+, 2010)
J/MNRAS/403/1368 : Li abundances+vsini for star-planet syst. (Gonzalez+, 2010)
J/other/Sci/330.653 : Detected planets in the Eta-Earth Survey (Howard+, 2010)
J/other/Sci/337.1511 : Kepler-47 transits (Orosz+, 2012)
J/ApJ/756/46 : Lithium abundances in HIP stars (Ramirez+, 2012)
J/A+A/562/A92 : Li abundance in solar analogues (Delgado Mena+, 2014)
J/ApJS/211/2 : Revised properties of Q1-16 Kepler targets (Huber+, 2014)
J/A+A/576/A69 : Li abundances in F stars (Delgado Mena+, 2015)
J/A+A/576/A89 : O abundances from HARPS in F-G stars (Bertran de Lis+, 2015)
J/MNRAS/446/1020 : Parent stars of extrasolar planets. XIV. (Gonzalez+, 2015)
J/MNRAS/462/1563 : Li to Eu in stars with & without planets (Mishenina+, 2016)
J/ApJS/224/12 : Kepler planetary candidates. VII. 48-month (Coughlin+, 2016)
J/AJ/154/107 : California-Kepler Survey (CKS). I. (Petigura+, 2017)
J/AJ/154/108 : California-Kepler Survey (CKS). II. (Johnson+, 2017)
J/AJ/154/109 : California-Kepler Survey (CKS). III. Radii (Fulton+, 2017)
http://exoplanetarchive.ipac.caltech.edu/ : NASA exoplanet archive
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Obs Observation Code (1)
11- 20 A10 "Y/M/D" Date Observation Date, UT, YYYY-MM-DD
22- 25 I04 --- KOI [1/7605] Kepler Object of Interest identifier
27- 31 F5.2 --- Kpmag [7.8/16.6] Magnitude in the Kepler bandpass
from the NASA Exoplanet Archive
33- 35 I3 --- S/N [5/223] Spectrum signal-to-noise
37- 40 I4 K Teff [4618/6656] Effective temperature (G1)
42- 45 F4.2 [cm/s2] logg [2.9/4.8] logarithm of surface gravity (G1)
47- 51 F5.2 [-] [Fe/H] [-0.7/0.5] Metallicity (G1)
53- 56 F4.2 km/s Vt [0.3/2] Microturbulent velocity (G2)
58- 62 F5.1 0.1pm EW(Li) [0.8/163] Equivalent width, Li,
in milli-Angstroms units
64- 67 F4.1 0.1pm e_EW(Li) [0.9/50] Uncertainty in EW(Li)
69- 73 F5.2 [-] A(Li) [-0.9/3.2] Lithium Abundance (12+log(Li/H))
75- 78 F4.2 [-] e_A(Li) [0.05/0.5]? Uncertainty in A(Li) (2)
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Note (1): The observation code is a combination of the HIRES outfile name and
the frame number for the given UT observation date. Example: j122.742
is the outfile j122 from frame number 742 on UT 2011-06-16. The
spectra can be found at:
http://koa.ipac.caltech.edu/cgi-bin/KOA/nph-KOAlogin?more or
http://california-planet-search.github.io/cks-website/
Or in Petigura+, 2017, J/AJ/154/107 (see the FTP).
Note (2): All items in the table which lack a given uncertainty for A(Li)
(e_A(Li) = "") indicate stars with EWLi<σUL+σEW,
which are flagged as upper limits in our analysis.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 I04 --- KOI [1/6759] Kepler Object of Interest identifier
6- 8 I3 --- S/N [13/181] Spectrum signal-to-noise
10- 13 I4 K Teff [4760/6656] Effective temperature (G1)
15- 18 F4.2 [cm/s2] logg [2.9/4.8] logarithm of surface gravity (G1)
20- 24 F5.2 [-] [Fe/H] [-0.5/0.5] Metallicity (G1)
26- 29 F4.2 km/s Vt [0.4/2] Microturbulent velocity (G2)
31- 35 F5.1 0.1pm EW(Li) [7.1/163] Equivalent width, Li,
in milli-Angstroms units
37- 40 F4.1 0.1pm e_EW(Li) [1.6/24] Uncertainty in EW(Li)
42- 45 F4.2 [-] A(Li) [0.4/3.2] Lithium Abundance (12+log(Li/H))
47- 50 F4.2 [-] e_A(Li) [0.05/0.4] Uncertainty in A(Li) (1)
52- 55 F4.2 --- dA(Li)Hy [0/4.4] delta Lithium abundance relative
to the Hyades
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Note (1): Upper limits are not given in this table.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 I04 --- KOI [1/5119] Kepler Object of Interest identifier
6- 6 A1 --- f_KOI System/Planet flags (1)
8- 11 I4 K Teff [4760/6532] Effective temperature (2)
13- 17 F5.1 0.1pm EW(Li) [9/163] Equivalent width, Li, milli-Angstroms
19- 22 F4.1 0.1pm e_EW(Li) [1.6/24] Uncertainty in EW(Li)
24- 27 F4.2 [-] A(Li) [0.4/3.2] Lithium Abundance (12+log(Li/H))
29- 32 F4.2 [-] e_A(Li) [0.05/0.4] Uncertainty in A(Li)
34- 37 F4.2 --- dA(Li)Hy [0.02/1.8] delta Lithium abundance relative
to the Hyades
39- 39 I1 --- Pl [1/4] KOI planet number
41- 44 F4.1 Rgeo Rp [0.6/39] Planet Radius, Earth units
46- 49 F4.1 Rgeo E_Rp [0.1/62] Upper uncertainty on Rp
51- 54 F4.1 Rgeo e_Rp [0.1/62] Lower uncertainty on Rp
56- 61 F6.1 d Per [1.1/1064.3] Planet orbital period
63- 65 F3.1 d E_Per [0] Upper uncertainty on Per (always "0.0")
67- 69 F3.1 d e_Per [0] Lower uncertainty on Per (always "0.0")
71- 76 F6.1 Earth Fp [0.7/7867] Planet insolation flux, Earth flux
78- 83 F6.1 Earth E_Fp [0.1/4771] Upper uncertainty on Fp
85- 90 F6.1 Earth e_Fp [0.1/4771] Lower uncertainty on Fp
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Note (1): All planets in this table are either confirmed planets (Pplanet≳0.99)
or planet candidates (Pplanet≳0.90) - no false positives are
included. Other System/Planet flags are as follows:
a = These planet sizes are too large to be physical. After further
investigation, we found that KOI 1230's companion has been dispositioned
as a certified false positive since we last accessed the NASA Exoplanet
Archive. KOI 3886's companion has also been dispositioned as a certified
false positive;
b = These systems have been modified with manually calculated Rp based on the
transit depth and the stellar radius due to a non-physical planet radius
in the California Kepler Survey (CKS) catalog.
Note (2): Errors in Teff are 60K.
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Global notes:
Note (G1): The stellar parameters Teff, log g, and [Fe/H] have uncertainties of
60K, 0.10dex, and 0.04dex, respectively; these are the adopted
values from Petigura+ (2017, J/AJ/154/107).
Note (G2): Employing Takeda+ (2013PASJ...65...53T 2013PASJ...65...53T)'s treatment of Vt.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 15-Jan-2019