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Title: STELLAR LOCI. I. METALLICITY DEPENDENCE AND INTRINSIC WIDTHS

Stellar loci are widely used for selection of interesting outliers, reddening determinations, and calibrations. However, until now, the dependence of stellar loci on metallicity has not been fully explored, and their intrinsic widths are unclear. In this paper, by combining the spectroscopic and recalibrated imaging data of the Sloan Digital Sky Survey (SDSS) Stripe 82, we have built a large, clean sample of dwarf stars with accurate colors and well-determined metallicities to investigate the metallicity dependence and intrinsic widths of the SDSS stellar loci. Typically, 1 dex decrease in metallicity causes 0.20 and 0.02 mag decrease in colors u – g and g – r and 0.02 and 0.02 mag increase in colors r – i and i – z, respectively. The variations are larger for metal-rich stars than for metal-poor ones, and larger for F/G/K stars than for A/M ones. Using the sample, we have performed two-dimensional polynomial fitting to the u – g, g – r, r – i, and i – z colors as a function of color g – i and metallicity [Fe/H]. The residuals, at the level of 0.029, 0.008, 0.008, and 0.011 mag for the u – g, g – r, r – i, and i – z colors, respectively, can be fully accounted for by the photometric errors and metallicity uncertainties, suggesting that the intrinsic widths of the loci are atmore » maximum a few millimagnitudes. The residual distributions are asymmetric, revealing that a significant fraction of stars are binaries. In a companion paper, we will present an unbiased estimate of the binary fraction for field stars. Other potential applications of the metallicity-dependent stellar loci are briefly discussed.« less
Authors:
;  [1] ; ; ;  [2]
  1. Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)
  2. Department of Astronomy, Peking University, Beijing 100871 (China)
Publication Date:
OSTI Identifier:
22364395
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 799; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASYMMETRY; BINARY STARS; COLOR; DATA ANALYSIS; DWARF STARS; ERRORS; METALLICITY; PHOTOMETRY; POLYNOMIALS; VARIATIONS