J/AJ/152/187 Planet occurrence and stellar metallicity for KOIs (Mulders+, 2016)
A super-solar metallicity for stars with hot rocky exoplanets.
Mulders G.D., Pascucci I., Apai D., Frasca A., Molenda-Zakowicz J.
<Astron. J., 152, 187-187 (2016)>
=2016AJ....152..187M 2016AJ....152..187M (SIMBAD/NED BibCode)
ADC_Keywords: Planets ; Stars, double and multiple ; Abundances, [Fe/H]
Keywords: planetary systems - planets and satellites: formation -
stars: abundances
Abstract:
Host star metallicity provides a measure of the conditions in
protoplanetary disks at the time of planet formation. Using a sample
of over 20000 Kepler stars with spectroscopic metallicities from the
LAMOST survey, we explore how the exoplanet population depends on host
star metallicity as a function of orbital period and planet size. We
find that exoplanets with orbital periods less than 10 days are
preferentially found around metal-rich stars
([Fe/H]≃0.15±0.05dex). The occurrence rates of these hot
exoplanets increases to ∼30% for super-solar metallicity stars from
∼10% for stars with a sub-solar metallicity. Cooler exoplanets, which
reside at longer orbital periods and constitute the bulk of the
exoplanet population with an occurrence rate of ≳90%, have host star
metallicities consistent with solar. At short orbital periods,
P<10days, the difference in host star metallicity is largest for hot
rocky planets (<1.7R⊕), where the metallicity difference is
[Fe/H]≃0.25±0.07dex. The excess of hot rocky planets around
metal-rich stars implies they either share a formation mechanism with
hot Jupiters, or trace a planet trap at the protoplanetary disk inner
edge, which is metallicity dependent. We do not find statistically
significant evidence for a previously identified trend that small
planets toward the habitable zone are preferentially found around
low-metallicity stars. Refuting or confirming this trend requires a
larger sample of spectroscopic metallicities.
Description:
The sample contains 665 planet candidates from the Q1-Q16 catalog
(Mullally et al. 2015, Cat. J/ApJS/217/31) after removing false
positives identified by Santerne et al. 2016 (Cat. J/A+A/587/A64). The
planet occurrence rates and host star metallicities are listed in
Table1.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 45 653 Planet occurrence rates and host star metallicities
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See also:
J/A+A/594/A39 : LAMOST-Kepler parameters & activity indicators (Frasca+, 2016)
J/A+A/587/A64 : Physical properties of giant exoplanets (Santerne+, 2016)
J/ApJS/224/12 : Kepler planetary candidates. VII. 48-month (Coughlin+, 2016)
J/ApJ/814/130 : Planet occurrence rates calculated for KOIs (Mulders+, 2015)
J/ApJ/810/95 : Kepler pipeline S/N studies. II. (Christiansen+, 2015)
J/ApJ/808/187 : Metallicities of KIC stars without planets (Buchhave+, 2015)
J/ApJS/220/19 : LAMOST obs. in the Kepler field. I. (De Cat+, 2015)
J/ApJS/217/31 : Kepler planetary candidates. VI. 4yr Q1-Q16 (Mullally+, 2015)
J/ApJS/211/2 : Revised properties of Q1-16 Kepler targets (Huber+, 2014)
J/other/Nat/486.375 : Stellar parameters of KOI stars (Buchhave+, 2012)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1 A1 --- --- [K]
2- 9 F08.2 --- KOI [1.01/6246.01] Kepler Object of Interest
identifier
11- 17 E7.1 cm Rp Planet radius
19- 23 F5.1 d Per [0.6/581.7] Orbital period
25- 31 E7.1 --- focc [0/0.22] Planet occurrence rate in entire sample
33- 37 F5.2 [Sun] [Fe/H] [-1.67/0.71] Stellar metallicity
39- 45 E7.1 --- foccsub [0/0.54] Planet occurrence rate per subsample:
denotes the occurence rate of the planet in the
super-solar or sub-solar metallicity sample (1)
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Note (1): Although we find a large difference in host star metallicity for
planets at short orbital periods, this is also the region where planet
occurrence rates are low compared to longer orbital periods. To assess how
the metallicity dependence of the short-period planets affects the overall
planet population, we calculate planet occurrence rate for a sub-sample of
sub-solar ([Fe/H]<0) and super-solar ([Fe/H]≥0) metallicities. Please
refer to Section 3.2 in the paper for more details about the planet
occurrence.
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 01-Feb-2017