The Metallicity of the CM Draconis System

Abstract

The CM Draconis system comprises two eclipsing mid-M dwarfs of nearly equal mass in a 1.27-day orbit. This well-studied eclipsing binary has often been used for benchmark tests of stellar models, since its components are amongst the lowest mass stars with well-measured masses and radii (~ 1% relative precision). However, as with many other low-mass stars, non-magnetic models have been unable to match the observed radii and effective temperatures for CM Dra at the 5-10% level. To date, the uncertain metallicity of the system has complicated comparison of theoretical isochrones with observations. In this Letter, we use data from the SpeX instrument on the NASA Infrared Telescope Facility (IRTF) to measure the metallicity of the system during primary and secondary eclipses, as well as out of eclipse, based on an empirical metallicity calibration in the H and K near-infrared (NIR) bands. We derive a [Fe/H] = -0.30 +- 0.12 that is consistent across all orbital phases. The determination of [Fe/H] for this system constrains a key dimension of parameter space when attempting to reconcile model isochrone predictions and observations.

Accepted to ApJ Letters

References in corpus (14)

• The Dartmouth Stellar Evolution Database
• Stellar Diameters and Temperatures II. Main Sequence K & M Stars
• Evolution of low-mass star and brown dwarf eclipsing binaries
• KOI-126: A Triply-Eclipsing Hierarchical Triple with Two Low-Mass Stars
• Efficient fitting of multiplanet Keplerian models to radial velocity and astrometry data
• The Neptune-Sized Circumbinary Planet Kepler-38b
• Absolute properties of the low-mass eclipsing binary CM Draconis
• APOGEE: The Apache Point Observatory Galactic Evolution Experiment
• The effect of activity on stellar temperatures and radii
• K-H_2 Quasi-molecular absorption detected in the T-dwarf epsilon Indi Ba
• Reevaluating the Mass-Radius Relation for Low-Mass, Main Sequence Stars
• An Empirical Correction for Activity Effects on the Temperatures, Radii, and Estimated Masses of Low-Mass Stars and Brown Dwarfs
• Stellar Population Models and Individual Element Abundances I: Sensitivity of Stellar Evolution Models
• The SDSS-HET Survey of Kepler Eclipsing Binaries: Spectroscopic Dynamical Masses of the Kepler-16 Circumbinary Planet Hosts

Cited by in corpus (29)

• The Solar Neighborhood XXXVII: The Mass-Luminosity Relation for Main Sequence M Dwarfs
• Magnetic Inhibition of Convection and the Fundamental Properties of Low-Mass Stars. I. Stars with a Radiative Core
• Older and Colder: The impact of starspots on pre-main sequence stellar evolution
• Magnetic Inhibition of Convection and the Fundamental Properties of Low-Mass Stars. II. Fully Convective Main Sequence Stars
• Self-Consistent Magnetic Stellar Evolution Models of the Detached, Solar-Type Eclipsing Binary EF Aquarii
• Fundamental properties of lower main-sequence stars
• Analysis of Early Science observations with the CHaracterising ExOPlanets Satellite (CHEOPS) using pycheops
• A Tale of Two Anomalies: Depletion, Dispersion, and the Connection Between the Stellar Lithium Spread and Inflated Radii on the Pre-Main Sequence
• A Near-Infrared Spectroscopic Survey of 886 Nearby M Dwarfs
• The Mass-Radius Relationship for Very Low Mass Stars: Four New Discoveries from the HATSouth Survey
• SOPHIE velocimetry of Kepler transit candidates. XIII. KOI-189 B and KOI-686 B: two very low-mass stars in long-period orbits
• Exploring the M-dwarf Luminosity--Temperature--Radius Relationships using Gaia DR2
• The SDSS-III APOGEE Radial Velocity Survey of M dwarfs I: Description of Survey and Science Goals
• Magnetic modeling of inflated low-mass stars using interior fields no larger than ~10 kilogauss
• A magnetic white dwarf in a detached eclipsing binary
• Testing Models of Stellar Structure and Evolution I. Comparison with Detached Eclipsing Binaries
• Magnetic Inflation and Stellar Mass I: Revised Parameters for the Component Stars of the Kepler Low-mass Eclipsing Binary T-Cyg1-12664
• Revised age for CM Draconis and WD 1633+572: Toward a resolution of model-observation radius discrepancies
• An eclipsing double-line spectroscopic binary at the stellar/substellar boundary in the Upper Scorpius OB association
• The Radius and Entropy of a Magnetized, Rotating Fully-convective Star: Analysis With Depth-dependent Mixing Length Theories
• Measuring Model-independent Masses and Radii of Single-Lined Eclipsing Binaries: Analytic Precision Estimates
• New Red Jewels in Coma Berenices
• A low-mass eclipsing binary within the fully convective zone from the NGTS
• HAT-TR-318-007: a double-lined M-dwarf binary with total secondary eclipses discovered by HATNet and observed by K2
• An eclipsing M-dwarf close to the hydrogen burning limit from NGTS
• NGTS J214358.5-380102 -- NGTS discovery of the most eccentric known eclipsing M-Dwarf binary system
• The SDSS-HET Survey of Kepler Eclipsing Binaries. Description of the Survey and First Results
• The first low-mass eclipsing binary within the fully convective zone from TMTS
• NGTS-EB-8: A double-lined eclipsing M+M binary discovered by citizen scientists