Metal-rich M-dwarf planet hosts: Metallicities with k-band spectra

Bárbara Rojas-Ayala, Kevin R. Covey, Philip S. Muirhead, James P. Lloyd

Resultado de la investigación: Article

95 Citas (Scopus)

Resumen

Ametal-rich environment facilitates planet formation, making metal-rich stars the most favorable targets for surveys seeking to detect new exoplanets. Using this advantage to identify likely low-mass planet hosts, however, has been difficult: until now methods to determine M-dwarf metallicities required observationally expensive data (such as parallaxes and high-resolution spectra) and were limited to a few bright cool stars. We have obtained moderate (R∼2700) resolutionK-band spectra of 17Mdwarfswith metallicity estimates derived from their FGK companions. Analysis of these spectra, and inspection of theoretical synthetic spectra, reveals that an M dwarf's metallicity can be inferred from the strength of its Na i doublet (2.206μm and 2.209μm) and Ca i triplet (2.261μm, 2.263μm, and 2.265μm) absorption lines.We use these features, and a temperature-sensitive water index, to construct an empirical metallicity indicator applicable for M dwarfs with near-solar metallicities (-0.5<[Fe/H] < +0.5). This indicator has an accuracy of ±0.15 dex, comparable to that of existing techniques for estimating M-dwarf metallicities, but is more observationally accessible, requiring only a moderate resolution K-band spectrum. Applyin g this method to eight known M-dwarf planet hosts, we estimate metallicities ([Fe/H]) in excess of the mean metallicity of M dwarfs in the solar neighborhood, consistent with the metallicity distribution of FGK planet hosts.

Idioma originalEnglish
PublicaciónAstrophysical Journal Letters
Volumen720
N.º1 PART 2
DOI
EstadoPublished - 1 sep 2010

Huella dactilar

dwarf planets
metallicity
planet
metal
metals
planets
cool stars
solar neighborhood
extrasolar planets
estimates
extremely high frequencies
inspection
estimating

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics
  • Nuclear and High Energy Physics

Citar esto

Rojas-Ayala, Bárbara ; Covey, Kevin R. ; Muirhead, Philip S. ; Lloyd, James P. / Metal-rich M-dwarf planet hosts : Metallicities with k-band spectra. En: Astrophysical Journal Letters. 2010 ; Vol. 720, N.º 1 PART 2.
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Metal-rich M-dwarf planet hosts : Metallicities with k-band spectra. / Rojas-Ayala, Bárbara; Covey, Kevin R.; Muirhead, Philip S.; Lloyd, James P.

En: Astrophysical Journal Letters, Vol. 720, N.º 1 PART 2, 01.09.2010.

Resultado de la investigación: Article

TY - JOUR

T1 - Metal-rich M-dwarf planet hosts

T2 - Metallicities with k-band spectra

AU - Rojas-Ayala, Bárbara

AU - Covey, Kevin R.

AU - Muirhead, Philip S.

AU - Lloyd, James P.

PY - 2010/9/1

Y1 - 2010/9/1

N2 - Ametal-rich environment facilitates planet formation, making metal-rich stars the most favorable targets for surveys seeking to detect new exoplanets. Using this advantage to identify likely low-mass planet hosts, however, has been difficult: until now methods to determine M-dwarf metallicities required observationally expensive data (such as parallaxes and high-resolution spectra) and were limited to a few bright cool stars. We have obtained moderate (R∼2700) resolutionK-band spectra of 17Mdwarfswith metallicity estimates derived from their FGK companions. Analysis of these spectra, and inspection of theoretical synthetic spectra, reveals that an M dwarf's metallicity can be inferred from the strength of its Na i doublet (2.206μm and 2.209μm) and Ca i triplet (2.261μm, 2.263μm, and 2.265μm) absorption lines.We use these features, and a temperature-sensitive water index, to construct an empirical metallicity indicator applicable for M dwarfs with near-solar metallicities (-0.5<[Fe/H] < +0.5). This indicator has an accuracy of ±0.15 dex, comparable to that of existing techniques for estimating M-dwarf metallicities, but is more observationally accessible, requiring only a moderate resolution K-band spectrum. Applyin g this method to eight known M-dwarf planet hosts, we estimate metallicities ([Fe/H]) in excess of the mean metallicity of M dwarfs in the solar neighborhood, consistent with the metallicity distribution of FGK planet hosts.

AB - Ametal-rich environment facilitates planet formation, making metal-rich stars the most favorable targets for surveys seeking to detect new exoplanets. Using this advantage to identify likely low-mass planet hosts, however, has been difficult: until now methods to determine M-dwarf metallicities required observationally expensive data (such as parallaxes and high-resolution spectra) and were limited to a few bright cool stars. We have obtained moderate (R∼2700) resolutionK-band spectra of 17Mdwarfswith metallicity estimates derived from their FGK companions. Analysis of these spectra, and inspection of theoretical synthetic spectra, reveals that an M dwarf's metallicity can be inferred from the strength of its Na i doublet (2.206μm and 2.209μm) and Ca i triplet (2.261μm, 2.263μm, and 2.265μm) absorption lines.We use these features, and a temperature-sensitive water index, to construct an empirical metallicity indicator applicable for M dwarfs with near-solar metallicities (-0.5<[Fe/H] < +0.5). This indicator has an accuracy of ±0.15 dex, comparable to that of existing techniques for estimating M-dwarf metallicities, but is more observationally accessible, requiring only a moderate resolution K-band spectrum. Applyin g this method to eight known M-dwarf planet hosts, we estimate metallicities ([Fe/H]) in excess of the mean metallicity of M dwarfs in the solar neighborhood, consistent with the metallicity distribution of FGK planet hosts.

KW - Planetary systems

KW - Stars: abundances

KW - Stars: late-type

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