Stellar loci IV. Red giant stars
arXiv:2109.06390 · doi:10.1088/1674-4527/21/12/319
Abstract
In the fourth paper of this series, we present the metallicity-dependent Sloan Digital Sky Survey (SDSS) stellar color loci of red giant stars, using a spectroscopic sample of red giants in the SDSS Stripe 82 region. The stars span a range of 0.55 -- 1.2 mag in color g-i, -0.3 -- -2.5 in metallicity [Fe/H], and have values of surface gravity log g smaller than 3.5 dex. As in the case of main-sequence (MS) stars, the intrinsic widths of loci of red giants are also found to be quite narrow, a few mmag at maximum. There are however systematic differences between the metallicity-dependent stellar loci of red giants and MS stars. The colors of red giants are less sensitive to metallicity than those of MS stars. With good photometry, photometric metallicities of red giants can be reliably determined by fitting the u-g, g-r, r-i, and i-z colors simultaneously to an accuracy of 0.2 -- 0.25 dex, comparable to the precision achievable with low-resolution spectroscopy for a signal-to-noise ratio of 10. By comparing fitting results to the stellar loci of red giants and MS stars, we propose a new technique to discriminate between red giants and MS stars based on the SDSS photometry. The technique achieves completeness of ~ 70 per cent and efficiency of ~ 80 per cent in selecting metal-poor red giant stars of [Fe/H] -1.2. It thus provides an important tool to probe the structure and assemblage history of the Galactic halo using red giant stars.
arXiv comment18 pages, 13 figures. Accepted for publication in Research in Astronomy and Astrophysics
References in corpus (20)
- Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
- The Sloan Digital Sky Survey: Technical Summary
- The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
- The Ninth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Baryon Oscillation Spectroscopic Survey
- SEGUE: A Spectroscopic Survey of 240,000 stars with g=14-20
- LSST Science Book, Version 2.0
- LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) The survey science plan
- The SEGUE Stellar Parameter Pipeline. I. Description and Initial Validation Tests
- Empirical extinction coefficients for the GALEX, SDSS, 2MASS and WISE passbands
- SDSS Standard Star Catalog for Stripe 82: the Dawn of Industrial 1% Optical Photometry
- The SEGUE Stellar Parameter Pipeline. II. Validation with Galactic Globular and Open Clusters
- Galactic Globular and Open Clusters in the Sloan Digital Sky Survey. I. Crowded Field Photometry and Cluster Fiducial Sequences in ugriz
- Mapping the Galactic Halo I. The `Spaghetti' Survey
- Mining SDSS in search of Multiple Populations in Globular Clusters
- The Stellar Metallicity Distribution Function of the Galactic Halo from SDSS Photometry
- Stellar loci II. a model-free estimate of the binary fraction for field FGK stars
- Stellar color regression: a spectroscopy based method for color calibration to a few mmag accuracy and the recalibration of Stripe 82
- Stellar loci I. Metallicity dependence and intrinsic widths
- Stellar loci III: Photometric metallicities for half million FGK stars of Stripe 82
- An Improved Photometric Calibration of the Sloan Digital Sky Survey Imaging Data