The Photometric Metallicity and Carbon Distributions of the Milky Way's Halo and Solar Neighborhood from S-PLUS Observations of SDSS Stripe 82

Abstract

We report photometric estimates of effective temperature, $T_{\mathrm{eff}}$, metallicity, [Fe/H], carbonicity, [C/Fe], and absolute carbon abundances, $A(\mathrm{C})$, for over 700,000 stars from the Southern Photometric Local Universe Survey (S-PLUS) Data Release 2, covering a substantial fraction of the equatorial Sloan Digital Sky Survey Stripe 82. We present an analysis for two stellar populations: 1) halo main-sequence turnoff stars and 2) K-dwarf stars of mass $0.58<M/M_{\odot }<0.75$ in the Solar Neighborhood. Application of the Stellar Photometric Index Network Explorer (SPHINX) to the mixed-bandwidth (narrow- plus wide-band) filter photometry from S-PLUS produces robust estimates of the metallicities and carbon abundances in stellar atmospheres over a wide range of temperature, $4250<T_{\mathrm{eff}}\text{(K)}<7000$. The use of multiple narrow-band S-PLUS filters enables SPHINX to achieve substantially lower levels of "catastrophic failures" (large offsets in metallicity estimates relative to spectroscopic determinations) than previous efforts using a single metallicity-sensitive narrow-band filter. We constrain the exponential slope of the Milky Way's K-dwarf halo metallicity distribution function (MDF), $\hat{I}{»}_{10,\text{[Fe/H]}}=0.85\pm 0.21$, over the metallicity range $-2.5<\text{[Fe/H]}<-1.0$; the MDF of our local-volume K-dwarf sample is well-represented by a gamma distribution with parameters $\hat{I}\pm =2.8$ and ${\hat{I}}^2=4.2$. S-PLUS photometry obtains absolute carbon abundances with a precision of $\sim 0.35$dex for stars with $T_{\mathrm{eff}}<6500$K. We identify 364 candidate carbon-enhanced metal-poor stars, obtain assignments of these stars into the Yoon-Beers morphological groups in the $A$(C)-[Fe/H] space, and derive the CEMP frequencies.

27 pages, 14 figures, 3 tables, Accepted for publication in ApJ