Examining the relationships between colour, $T_{\mathrm{eff}}$, and [M/H] for APOGEE K and M dwarfs

Abstract

We present the effective temperatures ($T_{\mathrm{eff}}$), metallicities, and colours in SDSS, 2MASS, and WISE filters, of a sample of 3834 late-K and early-M dwarfs selected from the Sloan Digital Sky Survey APOGEE spectroscopic survey ASPCAP catalog. We confirm that ASPCAP $T_{\mathrm{eff}}$ values between 3550 K$<T_{\mathrm{eff}}<$4200 K are accurate to $\sim$100 K compared to interferometric $T_{\mathrm{eff}}$ values. In that same $T_{\mathrm{eff}}$ range, ASPCAP metallicities are accurate to 0.18 dex between $-1.0<$[M/H]$<0.2$. For these cool dwarfs, nearly every colour is sensitive to both $T_{\mathrm{eff}}$ and metallicity. Notably, we find that $g-r$ is not a good indicator of metallicity for near-solar metallicity early-M dwarfs. We confirm that $J-K_S$ colour is strongly dependent on metallicity, and find that $W1-W2$ colour is a promising metallicity indicator. Comparison of the late-K and early-M dwarf colours, metallicities, and $T_{\mathrm{eff}}$ to those from three different model grids shows reasonable agreement in $r-z$ and $J-K_S$ colours, but poor agreement in $u-g$, $g-r$, and $W1-W2$. Comparison of the metallicities of the KM dwarf sample to those from previous colour-metallicity relations reveals a lack of consensus in photometric metallicity indicators for late-K and early-M dwarfs. We also present empirical relations for $T_{\mathrm{eff}}$ as a function of $r-z$ colour combined with either [M/H] or $W1-W2$ colour, and for [M/H] as a function of $r-z$ and $W1-W2$ colour. These relations yield $T_{\mathrm{eff}}$ to $\sim$100 K and [M/H] to $\sim$0.18 dex precision with colours alone, for $T_{\mathrm{eff}}$ in the range of 3550-4200 K and [M/H] in the range of $-$0.5-0.2.

14 pages, 6 tables, 5 figures, accepted for publication in MNRAS

References in corpus (15)

• The 2.5 m Telescope of the Sloan Digital Sky Survey
• The Dartmouth Stellar Evolution Database
• How to Constrain Your M Dwarf: measuring effective temperature, bolometric luminosity, mass, and radius
• Improving PARSEC models for very low mass stars
• The SEGUE Stellar Parameter Pipeline. I. Description and Initial Validation Tests
• Stellar SEDs from 0.3-2.5 Microns: Tracing the Stellar Locus and Searching for Color Outliers in SDSS and 2MASS
• A new implementation of the infrared flux method using the 2MASS catalogue
• Revised metallicity classes for low-mass stars: dwarfs (dM), subdwarfs (sdM), extreme subdwarfs (esdM), and ultra subdwarfs (usdM)
• M dwarfs: effective temperatures, radii and metallicities
• New H-band Stellar Spectral Libraries for the SDSS-III/APOGEE survey
• A Map of Dust Reddening to 4.5 kpc from Pan-STARRS1
• The SDSS-2MASS-WISE Ten Dimensional Stellar Color Locus
• Twenty-three new ultra-cool subdwarfs from the Sloan Digital Sky Survey
• A New Sample of Cool Subdwarfs from SDSS: Properties and Kinematics
• M dwarf luminosity, radius, and $\alpha$-enrichment from $I$-band spectral features

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