M dwarfs: effective temperatures, radii and metallicities

2008/06/15 by Luca Casagrande, L. Casagrande, Chris Flynn +3
Physics and Astronomy · #Astronomy and Astrophysical Research #Bolometer #Brown dwarf #Effective temperature #Luminosity #Metallicity #Photometry (optics) #Proper motion #Scaling #Scientific Research and Discoveries #Stars #Stellar, planetary, and galactic studies #astro-ph

paper · pdf · doi:10.1111/j.1365-2966.2008.13573.x

published as Mon.Not.Roy.Astron.Soc. 389 (2008) 585-607 · 26 pages, 14 figures. Accepted by MNRAS. Landscape table available online at http://users.utu.fi/luccas/MOITE/

arxiv created 2008/06/15 · openalex publication_date 2008/08/12 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05

Abstract

We empirically determine effective temperatures and bolometric luminosities for a large sample of nearby M dwarfs, for which high accuracy optical and infrared photometry is available. We introduce a new technique which exploits the flux ratio in different bands as a proxy of both effective temperature and metallicity. Our temperature scale for late-type dwarfs extends well below 3000 K (almost to the brown dwarf limit) and is supported by interferometric angular diameter measurements above 3000 K. Our metallicities are in excellent agreement (usually within 0.2 dex) with recent determinations via independent techniques. A subsample of cool M dwarfs with metallicity estimates based on hotter Hipparcos common proper motion companions indicates our metallicities are also reliable below 3000 K, a temperature range unexplored until now. The high quality of our data allows us to identify a striking feature in the bolometric luminosity versus temperature plane, around the transition from K to M dwarfs. We have compared our sample of stars with theoretical models and conclude that this transition is due to an increase in the radii of the M dwarfs, a feature which is not reproduced by theoretical models.

Citations

• The helium abundance and ΔY/ΔZ in lower main-sequence stars
• An expanded set of brown dwarf and very low mass star models
• Calibrating M Dwarf Metallicities Using Molecular Indices
• Masses and Radii of Low-Mass Stars: Theory Versus Observations
• Chromospheric activity, kinematics, and metallicities of nearby M dwarfs
• The First Direct Measurements of Surface Magnetic Fields on Very Low Mass Stars
• Accurate fundamental parameters for lower main-sequence stars
• Constraints on thick disc and halo parameters from HST photometry of field stars in the Galaxy
• The Lower Main Sequence and the Orbital Period Distribution of Cataclysmic Variable Stars
• Angular Diameters of Stars from the Mark III Optical Interferometer
• Absolute Dimensions of the M‐Type Eclipsing Binary YY Geminorum (Castor C): A Challenge to Evolutionary Models in the Lower Main Sequence
• First radius measurements of very low mass stars with the VLTI
• Accurate M Dwarf Metallicities from Spectral Synthesis: A Critical Test of Model Atmospheres
• Metallicities of M Dwarf Planet Hosts from Spectral Synthesis
• Model atmospheres for M (sub)dwarf stars. 1: The base model grid
• Infrared Spectra of Low-Mass Stars: Toward a Temperature Scale for Red Dwarfs
• The Solar Neighborhood. X. New Nearby Stars in the Southern Sky and Accurate Photometric Distance Estimates for Red Dwarfs
• Barnard's Star and the M Dwarf Temperature Scale
• Metallicity measurements using atomic lines in M and K dwarf stars
• Spectral Irradiance Calibration in the Infrared. XIV. The Absolute Calibration of 2MASS
• The interferometric diameter and internal structure of Sirius A
• Spheroid Luminosity and Mass Functions fromHubble Space TelescopeStar Counts
• Carbon monoxide bands in M dwarfs
• UBVRI passbands
• The NextGen Model Atmosphere Grid for \documentclassaastex \usepackageamsbsy \usepackageamsfonts \usepackageamssymb \usepackagebm \usepackagemathrsfs \usepackagepifont \usepackagestmaryrd \usepackagetextcomp \usepackageportland,xspace \usepackageamsmath,amsxtra \usepackage[OT2,OT1]fontenc \newcommand\cyr \renewcommand\rmdefaultwncyr \renewcommand\sfdefaultwncyss \renewcommand\encodingdefaultOT2 \normalfont \selectfont \DeclareTextFontCommand\textcyr\cyr \pagestyleempty \DeclareMathSizes10976 \begindocument \landscape 3000≤ T_eff ≤ 10,000 \enddocument K
• The HARPS search for southern extra-solar planets XI. Super-Earths (5 & 8 M_Earth) in a 3-planet system