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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



ID: 710139.0, MPI für Astronomie / Publikationen_mpia
Prospecting in ultracool dwarfs: Measuring the metallicities of mid- and late-M dwarfs
Authors:Mann, A. W.; Deacon, N. R.; Gaidos, E.; Ansdell, M.; Brewer, J. M.; Liu, M. C.; Magnier, E. A.; Aller, K. M.
Date of Publication (YYYY-MM-DD):2014
Title of Journal:The Astronomical Journal
Volume:147
Issue / Number:6
Start Page:160
Audience:Not Specified
Abstract / Description:Metallicity is a fundamental parameter that contributes to the physical characteristics of a star. The low temperatures and complex molecules present in M dwarf atmospheres make it difficult to measure their metallicities using techniques that have been commonly used for Sun-like stars. Although there has been significant progress in developing empirical methods to measure M dwarf metallicities over the last few years, these techniques have been developed primarily for early- to mid-M dwarfs. We present a method to measure the metallicity of mid- to late-M dwarfs from moderate resolution (R ~ 2000) K-band (sime 2.2 mum) spectra. We calibrate our formula using 44 wide binaries containing an F, G, K, or early-M primary of known metallicity and a mid- to late-M dwarf companion. We show that similar features and techniques used for early-M dwarfs are still effective for late-M dwarfs. Our revised calibration is accurate to ~0.07 dex for M4.5-M9.5 dwarfs with -0.58 < [Fe/H] < +0.56 and shows no systematic trends with spectral type, metallicity, or the method used to determine the primary star metallicity. We show that our method gives consistent metallicities for the components of M+M wide binaries. We verify that our new formula works for unresolved binaries by combining spectra of single stars. Lastly, we show that our calibration gives consistent metallicities with the Mann et al. study for overlapping (M4-M5) stars, establishing that the two calibrations can be used in combination to determine metallicities across the entire M dwarf sequence.
Free Keywords:binaries: visual; stars: abundances; stars: fundamental parameters; stars: late-type; techniques: spectroscopic
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-6256 %R 10.1088/0004-6256/147/6/160
URL:http://cdsads.u-strasbg.fr/abs/2014AJ....147..160M
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