Bibcode
Souto, D.; Cunha, K.; García-Hernández, D. A.; Zamora, O.; Allende Prieto, C.; Smith, V. V.; Mahadevan, S.; Blake, C.; Johnson, J. A.; Jönsson, H.; Pinsonneault, M.; Holtzman, J.; Majewski, S. R.; Shetrone, M.; Teske, J.; Nidever, D.; Schiavon, R.; Sobeck, J.; García Pérez, A. E.; Gómez Maqueo Chew, Y.; Stassun, K.
Bibliographical reference
The Astrophysical Journal, Volume 835, Issue 2, article id. 239, 12 pp. (2017).
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2
2017
Journal
Citations
46
Refereed citations
40
Description
We report the first detailed chemical abundance analysis of the
exoplanet-hosting M-dwarf stars Kepler-138 and Kepler-186 from the
analysis of high-resolution (R ∼ 22,500) H-band spectra from the
SDSS-IV–APOGEE survey. Chemical abundances of 13 elements—C,
O, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, and Fe—are extracted from
the APOGEE spectra of these early M-dwarfs via spectrum syntheses
computed with an improved line list that takes into account
H2O and FeH lines. This paper demonstrates that APOGEE
spectra can be analyzed to determine detailed chemical compositions of
M-dwarfs. Both exoplanet-hosting M-dwarfs display modest sub-solar
metallicities: [Fe/H]Kepler-138 = ‑0.09 ± 0.09
dex and [Fe/H]Kepler-186 = ‑0.08 ± 0.10 dex. The
measured metallicities resulting from this high-resolution analysis are
found to be higher by ∼0.1–0.2 dex than previous estimates
from lower-resolution spectra. The C/O ratios obtained for the two
planet-hosting stars are near-solar, with values of 0.55 ± 0.10
for Kepler-138 and 0.52 ± 0.12 for Kepler-186. Kepler-186
exhibits a marginally enhanced [Si/Fe] ratio.
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