Metallicity and temperature indicators in Mdwarf K-band spectra: Testing new and updated calibrations with observations of 133 solar neighborhood Mdwarfs

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

Resultado de la investigación: Article

179 Citas (Scopus)

Resumen

We present K-band spectra for 133 nearby (d < 33 ps) Mdwarfs, including 18 Mdwarfs with reliable metallicity estimates (as inferred from an FGK type companion), 11 Mdwarf planet hosts, more than 2/3 of the Mdwarfs in the northern 8 pc sample, and several Mdwarfs from the LSPM catalog. From these spectra, we measure equivalent widths of the Ca and Na lines, and a spectral index quantifying the absorption due to H2O opacity (the H2O-K2 index). Using empirical spectral type standards and synthetic models, we calibrate the H2O-K2 index as an indicator of an Mdwarf's spectral type and effective temperature. We also present a revised relationship that estimates the [Fe/H] and [M/H] metallicities of Mdwarfs from their Na I, Ca I, and H2O-K2 measurements. Comparisons to model atmosphere provide a qualitative validation of our approach, but also reveal an overall offset between the atomic line strengths predicted by models as compared to actual observations. Our metallicity estimates also reproduce expected correlations with Galactic space motions and Hα emission line strengths, and return statistically identical metallicities for Mdwarfs within a common multiple system. Finally, we find systematic residuals between our H2O-based spectral types and those derived from optical spectral features with previously known sensitivity to stellar metallicity, such as TiO, and identify the CaH1 index as a promising optical index for diagnosing the metallicities of near-solar Mdwarfs.

Idioma originalEnglish
Número de artículo93
PublicaciónAstrophysical Journal
Volumen748
N.º2
DOI
EstadoPublished - 1 abr 2012

Huella dactilar

temperature indicators
solar neighborhood
extremely high frequencies
metallicity
calibration
temperature
estimates
opacity
planet
catalogs
indicator
index
planets
atmosphere
atmospheres
sensitivity

ASJC Scopus subject areas

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

Citar esto

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abstract = "We present K-band spectra for 133 nearby (d < 33 ps) Mdwarfs, including 18 Mdwarfs with reliable metallicity estimates (as inferred from an FGK type companion), 11 Mdwarf planet hosts, more than 2/3 of the Mdwarfs in the northern 8 pc sample, and several Mdwarfs from the LSPM catalog. From these spectra, we measure equivalent widths of the Ca and Na lines, and a spectral index quantifying the absorption due to H2O opacity (the H2O-K2 index). Using empirical spectral type standards and synthetic models, we calibrate the H2O-K2 index as an indicator of an Mdwarf's spectral type and effective temperature. We also present a revised relationship that estimates the [Fe/H] and [M/H] metallicities of Mdwarfs from their Na I, Ca I, and H2O-K2 measurements. Comparisons to model atmosphere provide a qualitative validation of our approach, but also reveal an overall offset between the atomic line strengths predicted by models as compared to actual observations. Our metallicity estimates also reproduce expected correlations with Galactic space motions and Hα emission line strengths, and return statistically identical metallicities for Mdwarfs within a common multiple system. Finally, we find systematic residuals between our H2O-based spectral types and those derived from optical spectral features with previously known sensitivity to stellar metallicity, such as TiO, and identify the CaH1 index as a promising optical index for diagnosing the metallicities of near-solar Mdwarfs.",
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Metallicity and temperature indicators in Mdwarf K-band spectra : Testing new and updated calibrations with observations of 133 solar neighborhood Mdwarfs. / Rojas-Ayala, Bárbara; Covey, Kevin R.; Muirhead, Philip S.; Lloyd, James P.

En: Astrophysical Journal, Vol. 748, N.º 2, 93, 01.04.2012.

Resultado de la investigación: Article

TY - JOUR

T1 - Metallicity and temperature indicators in Mdwarf K-band spectra

T2 - Testing new and updated calibrations with observations of 133 solar neighborhood Mdwarfs

AU - Rojas-Ayala, Bárbara

AU - Covey, Kevin R.

AU - Muirhead, Philip S.

AU - Lloyd, James P.

PY - 2012/4/1

Y1 - 2012/4/1

N2 - We present K-band spectra for 133 nearby (d < 33 ps) Mdwarfs, including 18 Mdwarfs with reliable metallicity estimates (as inferred from an FGK type companion), 11 Mdwarf planet hosts, more than 2/3 of the Mdwarfs in the northern 8 pc sample, and several Mdwarfs from the LSPM catalog. From these spectra, we measure equivalent widths of the Ca and Na lines, and a spectral index quantifying the absorption due to H2O opacity (the H2O-K2 index). Using empirical spectral type standards and synthetic models, we calibrate the H2O-K2 index as an indicator of an Mdwarf's spectral type and effective temperature. We also present a revised relationship that estimates the [Fe/H] and [M/H] metallicities of Mdwarfs from their Na I, Ca I, and H2O-K2 measurements. Comparisons to model atmosphere provide a qualitative validation of our approach, but also reveal an overall offset between the atomic line strengths predicted by models as compared to actual observations. Our metallicity estimates also reproduce expected correlations with Galactic space motions and Hα emission line strengths, and return statistically identical metallicities for Mdwarfs within a common multiple system. Finally, we find systematic residuals between our H2O-based spectral types and those derived from optical spectral features with previously known sensitivity to stellar metallicity, such as TiO, and identify the CaH1 index as a promising optical index for diagnosing the metallicities of near-solar Mdwarfs.

AB - We present K-band spectra for 133 nearby (d < 33 ps) Mdwarfs, including 18 Mdwarfs with reliable metallicity estimates (as inferred from an FGK type companion), 11 Mdwarf planet hosts, more than 2/3 of the Mdwarfs in the northern 8 pc sample, and several Mdwarfs from the LSPM catalog. From these spectra, we measure equivalent widths of the Ca and Na lines, and a spectral index quantifying the absorption due to H2O opacity (the H2O-K2 index). Using empirical spectral type standards and synthetic models, we calibrate the H2O-K2 index as an indicator of an Mdwarf's spectral type and effective temperature. We also present a revised relationship that estimates the [Fe/H] and [M/H] metallicities of Mdwarfs from their Na I, Ca I, and H2O-K2 measurements. Comparisons to model atmosphere provide a qualitative validation of our approach, but also reveal an overall offset between the atomic line strengths predicted by models as compared to actual observations. Our metallicity estimates also reproduce expected correlations with Galactic space motions and Hα emission line strengths, and return statistically identical metallicities for Mdwarfs within a common multiple system. Finally, we find systematic residuals between our H2O-based spectral types and those derived from optical spectral features with previously known sensitivity to stellar metallicity, such as TiO, and identify the CaH1 index as a promising optical index for diagnosing the metallicities of near-solar Mdwarfs.

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KW - stars: fundamental parameters

KW - stars: late-type

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