Chemical Abundances of M-Dwarfs from the Apogee Survey. I. The Exoplanet Hosting Stars Kepler-138 and Kepler-186

Journal Article · Wed Feb 01 00:00:00 EST 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/835/2/239· OSTI ID:22663891

Souto, D.; Cunha, K. ^[1]; García-Hernández, D. A.; Zamora, O.; Prieto, C. Allende; Jönsson, H.; Pérez, A. E. García ^[2]; Smith, V. V. ^[3]; Mahadevan, S. ^[4]; Blake, C. ^[5]; Johnson, J. A.; Pinsonneault, M. ^[6]; Holtzman, J. ^[7]; Majewski, S. R.; Sobeck, J. ^[8]; Shetrone, M. ^[9]; Teske, J. ^[10]; Nidever, D. ^[11]; Schiavon, R. ^[12]; others, and

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1. Observatório Nacional, Rua General José Cristino, 77, 20921-400 São Cristóvão, Rio de Janeiro, RJ (Brazil)
2. Instituto de Astrofísica de Canarias (IAC), Vía Lactea S/N, E-38205, La Laguna, Tenerife (Spain)
3. National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)
4. Department of Astronomy and Astrophysics, The Pennsylvania State University (United States)
5. Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States)
6. Department of Astronomy, The Ohio State University, Columbus, OH 43210 (United States)
7. New Mexico State University, Las Cruces, NM 88003 (United States)
8. Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States)
9. University of Texas at Austin, McDonald Observatory (United States)
10. Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington, DC 20015 (United States)
11. Department of Astronomy, University of Michigan, Ann Arbor, MI, 48104 (United States)
12. Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool, L3 5RF (United Kingdom)

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 H{sub 2}O 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]{sub Kepler-138} = −0.09 ± 0.09 dex and [Fe/H]{sub 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.

• OSTI ID: 22663891
• Journal Information: Astrophysical Journal, Vol. 835, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ABUNDANCE
CHEMICAL COMPOSITION
CONCENTRATION RATIO
DWARF STARS
INTERACTIONS
MASS
METALLICITY
PLANETS
RESOLUTION
SPECTRA
SYNTHESIS
WATER