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J/MNRAS/389/585     Fundamental parameters of M dwarfs     (Casagrande+, 2008)

M dwarfs: effective temperatures, radii and metallicities. Casagrande L., Flynn C., Bessell M. <Mon. Not. R. Astron. Soc., 389, 585-607 (2008)> =2008MNRAS.389..585C
ADC_Keywords: Stars, dwarfs ; Stars, M-type ; Photometry, UBVRI ; Photometry, infrared ; Effective temperatures Keywords: stars: abundances - stars: atmospheres - stars: fundamental parameters - Hertzsprung-Russell (HR) diagram - stars: low-mass, brown dwarf - infrared: stars 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 3000K (almost to the brown dwarf limit) and is supported by interferometric angular diameter measurements above 3000K. Our metallicities are in excellent agreement (usually within 0.2dex) 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 3000K, 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. Description: Our basic sample consists of 343 nearby M dwarfs with high-quality optical and IR photometry. We apply an extension of the IRFM we developed for G and K dwarfs (Casagrande et al., 2006, Cat. J/MNRAS/373/13) to M dwarfs. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 100 343 Observable and physical quantities for our sample stars
See also: J/MNRAS/334/20 : UBV(RI)c photometry of HIP red stars (Koen+, 2002) J/AJ/123/2822 : Photometry of southern NLTT stars (Reid+, 2002) J/AJ/126/3007 : Spectroscopy of faint red NLTT dwarfs (Reid+, 2003) J/AJ/128/463 : A preliminary 20pc census from NLTT catalogue (Reid+, 2004) J/MNRAS/373/13 : Lower main-sequence stars fund. param. (Casagrande+, 2006) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 14 A14 --- Name Star name 16- 19 I4 K Teff Effective temperature 21- 23 I3 K e_Teff rms uncertainty on Teff 25- 29 F5.3 mas theta Angular diameter 31- 35 F5.3 mas e_theta rms uncertainty on theta 37- 42 F6.3 mag mBol Apparent bolometric magnitude (1) 44- 49 F6.3 mag Vmag Johnson V magnitude 51- 55 F5.3 mag B-V ?=- Johnson B-V colour index 57- 61 F5.3 mag U-B ?=- Johnson U-B colour index 63- 67 F5.3 mag V-Rc Johnson-Cousins V-Rc colour index 69- 73 F5.3 mag V-Ic Johnson-Cousins V-Ic colour index 75- 80 F6.3 mag Jmag 2MASS Johnson J magnitude 82- 87 F6.3 mag Hmag 2MASS Johnson H magnitude 89- 94 F6.3 mag Ksmag 2MASS Johnson Ks magnitude 96-100 F5.2 [-] [M/H] ?=- Metallicity (2)
Note (1): Apparent bolometric magnitudes (mBol) are obtained according to Section 6, where the absolute bolometric magnitude of the Sun MBol,sun=4.74. Note (2): For the stars with HIP number, the metallicities are from the Bonfils et al. (2005A&A...442..635B) calibration, while the remainder are obtained with the MOITE.
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 09-Feb-2009
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