J/A+A/547/A36 Chemical abundances of 87 KOIs (Adibekyan++, 2012)
Exploring the alpha-enhancement of metal-poor planet-hosting stars.
The Kepler + HARPS samples.
Adibekyan V.Zh., Delgado Mena E., Sousa G., Santos N.C., Israelian G.,
Gonzalez Hernandez J.I., Mayor M., Hakobyan A.A.
<Astron. Astrophys. 547, A36 (2012)>
=2012A&A...547A..36A 2012A&A...547A..36A
ADC_Keywords: Stars, nearby ; Stars, double and multiple ; Planets ;
Abundances, peculiar
Keywords: stars: abundances - planetary systems
Abstract:
Recent studies showed that at low metallicities Doppler-detected
planet-hosting stars have preferably high alpha-content and belong to
the thick disk.We used the reconnaissance spectra of 87 Kepler planet
candidates and data available from the HARPS planet search survey to
explore this phenomena. Using the traditional spectroscopic abundance
analysis methods we derived Ti, Ca, and Cr abundances for the Kepler
stars. In the metallicity region -0.65<[Fe/H]←0.3dex the fraction of
Ti-enhanced thick-disk HARPS planet harboring stars is 12.3±4.1% and
for their thin-disk counterparts this fraction is 2.2±1.3%. The
binomial statistics gives a probability of 0.008 that this could have
occurred by chance. Combining the two samples (HARPS + Kepler)
reinforces the significance of this result (P∼99.97%). Since most of
these stars are harboring small-mass/size planets we can assume that,
although terrestrial planets can be found at low-iron regime, they are
mostly enhanced by alpha-elements. This implies that early formation
of rocky planets could get started in the Galactic thick disk, where
the chemical conditions for their formation were more favorable.
Description:
Chemical abundances of 87 Kepler planet host candidates.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table.dat 27 87 Abundances for each star and element
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
J/A+A/497/563 : Chemical abundances of 451 stars (Neves+, 2009)
J/A+A/545/A32 : Chemical abundances of 1111 stars (Adibekyan+, 2012)
Byte-by-byte Description of file: table.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- --- [k0]
3- 6 I4 --- KOI Star's identifier (<KOI-NNNNN> in Simbad)
8- 13 F6.3 [Sun] [Cr/H] ? Abundance [Cr/H] (Z=24.0) (1)
15- 20 F6.3 [Sun] [Ca/H] ? Abundance [Ca/H] (Z=20.0) (1)
22- 27 F6.3 [Sun] [Ti/H] ? Abundance [Ti/H] (Z=22.0) (1)
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Note (1): Abundances for selected elements;
logε0(CaI) = 6.36
logε0(TiI) = 4.99
logε0(CrI) = 5.67
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Acknowledgements:
Vardan Adibekyan, Vardan.Adibekyan(at)astro.up.pt
(End) Vardan Adibekyan [CAUP], Patricia Vannier [CDS] 01-Oct-2012