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The Milky Way's metal-poor stars are nearby ancient objects that are used to study early chemical evolution and the assembly and structure of the Milky Way. Here we present reliable metallicities of $\sim280,000$ stars with $-3.75 \lesssim$…

Astrophysics of Galaxies · Physics 2021-06-09 Anirudh Chiti , Anna Frebel , Mohammad K. Mardini , Tatsuya W. Daniel , Xiaowei Ou , Anastasiia V. Uvarova

We present a theoretical calibration of a new metallicity diagnostic based on the Stroemgren index m1 and on visual -- near-infrared (NIR) colors to estimate the global metal abundance of cluster and field dwarf stars. To perform the…

Solar and Stellar Astrophysics · Physics 2015-06-05 Annalisa Calamida , M. Monelli , A. P. Milone , G. Bono , A. Pietrinferni , E. P. Lagioia

With the aid of stellar atmosphere models, we derive iron abundances [Fe/H] from the OGLE B, V, I photometry on the Magellanic Cloud Cepheids. We show that in both clouds the average metallicities of the first overtone variables are lower…

Astrophysics · Physics 2015-05-13 Geza Kovacs

Knowledge of late K and M dwarf metallicities can be used to guide planet searches and constrain planet formation models. However, the determination of metallicities of late-type stars is difficult because visible wavelength spectra of…

Solar and Stellar Astrophysics · Physics 2014-05-16 Andrew W. Mann , John M. Brewer , Eric Gaidos , Sebastien Lepine , Eric J. Hilton

We present ISOCAM 7 micron and 15 micron observations of 12 nearby white dwarfs, 6 of which have been found to have metals such as Ca, Mg and Fe in their photospheres. Our purpose was to search for an excess of infrared emission above the…

Astrophysics · Physics 2007-05-23 R. Chary , B. Zuckerman , E. E. Becklin

The location of M dwarfs in the V-K_s--M_Ks color-magnitude diagram (CMD) has been shown to correlate with metallicity. We demonstrate that previous empirical photometric calibrations of M dwarf metallicity exploiting this correlation…

Earth and Planetary Astrophysics · Physics 2015-05-19 Kevin C. Schlaufman , Gregory Laughlin

We report new measurements of carbon and oxygen abundances in 34 F and G dwarf and subgiant stars belonging to the halo population and spanning a range of metallicity from [Fe/H] = -0.7 to -3.2 . The survey is based on observations of four…

Astrophysics · Physics 2008-11-26 Chris J. Akerman , Leticia Carigi , Poul E. Nissen , Max Pettini , Martin Asplund

Stellar population models with abundance distributions determined from the analytic Simple model of chemical evolution fail to match observations of the nuclei of bulge-dominated galaxies in three respects. First, the spectral energy…

Astrophysics · Physics 2009-10-28 Guy Worthey , Ben Dorman , Lewis Jones

We present an improved uvby-metallicity relation calibrated for F, G, and early K dwarfs, and an analogous uvby-T(eff) relation, both derived using a Levenberg-Marquardt minimization scheme. Our calibrations are based on 1533 stars which…

Astrophysics · Physics 2015-06-24 Sarah Martell , Gregory Laughlin

We investigate the stellar metallicity ([Fe/H] and [M/H]) dependence of giant planets around M dwarfs by comparing the metallicity distribution of 746 field M dwarfs without known giant planets with a sample of 22 M dwarfs hosting confirmed…

Earth and Planetary Astrophysics · Physics 2024-12-12 Tianjun Gan , Christopher A. Theissen , Sharon X. Wang , Adam J. Burgasser , Shude Mao

We report the first survey of chemical abundances in M and K dwarf stars using atomic absorption lines in high resolution spectra. We have measured Fe and Ti abundances in 35 M and K dwarf stars using equivalent widths measured from (lambda…

Astrophysics · Physics 2009-11-10 Vincent M. Woolf , George Wallerstein

Over a quarter of white dwarfs have photospheric metal pollution, which is evidence for recent accretion of exoplanetary material. While a wide range of mechanisms have been proposed to account for this pollution, there are currently few…

Stellar evolutionary tracks for $0.12 \le M/M_\odot \le 1.0$ have been computed for each of several variations in the abundances of C, N, and O, assuming mass-fraction helium abundances $Y = 0.25$ and $0.29$, and 11 metallicities in the…

Solar and Stellar Astrophysics · Physics 2022-11-30 Don A. VandenBerg

Comparisons between the planet populations around solar-type stars and those orbiting M dwarfs shed light on the possible dependence of planet formation and evolution on stellar mass. However, such analyses must control for other factors,…

Earth and Planetary Astrophysics · Physics 2015-06-22 Eric Gaidos , Andrew W. Mann

We present the analysis of an extensive set of new and literature high quality data concerning Fe, C, N, O, Na, and Mg, exploiting the Teff scale determined in Gratton et al. (1996), and the non-LTE abundance corrections computed in Gratton…

Astrophysics · Physics 2007-05-23 Eugenio Carretta , Raffaele Gratton , Chris Sneden

Deriving metallicities for solar-like stars follows well-established methods, but for cooler stars such as M dwarfs, the determination is much more complicated due to forests of molecular lines that are present. Several methods have been…

We present metallicity measurements of 25 stars in the blue horizontal branch of the Galactic globular cluster NGC 2808. Our measurements are based on moderate-resolution spectra taken with the multi-object fiber facility FLAMES-UVES,…

Astrophysics · Physics 2007-05-23 G. Pace , A. Recio-Blanco , G. Piotto , Y. Momany

While the planet-metallicity correlation for FGK main-sequence stars hosting giant planets is well established, the results are not so clear for M-dwarf stars, for which precise metallicity measurements are not straightforward. However, new…

Solar and Stellar Astrophysics · Physics 2017-11-15 M. J. Hobson , E. Jofré , L. García , R. Petrucci , M. Gómez

We report the statistical properties of stars and brown dwarfs obtained from four radiation hydrodynamical simulations of star cluster formation, the metallicities of which span a range from 1/100 to 3 times the solar value. Unlike previous…

Solar and Stellar Astrophysics · Physics 2019-01-15 Matthew R. Bate

We study the metal abundances of F and G type stars in the Galactic disk and halo using the Canada-France-Hawaii Telescope Legacy Survey D4 field. For a sample of stars within 7 kpc of the Galactic plane, we derive mean abundance values of…

Astrophysics · Physics 2009-11-13 Y. Karatas , M. Kilic , O. Gunes , F. Limboz