J/A+A/564/A90 M subdwarfs VLT/UVES high resolution spectra (Rajpurohit+, 2014)
A high resolution spectroscopic atlas of M subdwarfs. Effective temperature and
metallicity.
Rajpurohit A.S., Reyle C., Allard F., Scholz R.-D., Homeier D.,
Schultheis M., Bayo A.
<Astron. Astrophys. 564, A90 (2014)>
=2014A&A...564A..90R 2014A&A...564A..90R
ADC_Keywords: Stars, M-type ; Stars, K-type ; Stars, subdwarf ; Spectroscopy
Keywords: stars: atmospheres - stars: fundamental parameters - stars: low-mass -
subdwarfs
Abstract:
M subdwarfs are metal poor and cool stars. They are important probes
of the old galactic populations. However, they remain elusive due to
their low luminosity. Observational and modeling efforts are required
to fully understand their physics and to investigate the effects of
metallicity in their cool atmospheres.
We perform a detailed study of a sample of subdwarfs to determine
their stellar parameters and constrain the stat-of-the art atmospheric
models.
We present UVES/VLT high resolution spectra of three late-K subdwarfs
and 18 M subdwarfs. Our atlas covers the optical region from 6400Å
up to the near infrared at 8900Å. We show spectral details of cool
atmospheres at very high resolution (R∼40000) and compare with
synthetic spectra computed from the recent BT-Settl atmosphere models.
Our comparison shows that molecular features (TiO, VO, CaH), and
atomic features (FeI, TiI, NaI, KI) are well fitted by current
models. We produce an effective temperature versus spectral type
relation all over the subdwarf spectral sequence. Thanks to the high
resolution of our spectra, we perform a detailed comparison of line
profiles of individual elements such as FeI, CaII, TiI, and are
able to determine accurate metallicities of these stars. These
determinations contribute to calibrate the relation between
metallicity and molecular band strength indices from low-resolution
spectra.
This work shows that the new generation of models are able to
reproduce various spectral features of M subdwarfs. Working with these
high resolution spectra allowed us to disentangle the atmospheric
parameters (effective temperature, gravity, metallicity), which is not
possible when using low resolution spectroscopy or photometry.
Description:
Spectral types, near-infrared photometry, and spectral indices of 21 K
and M subdwarfs. The photometry and coordinates are taken from 2MASS,
at epochs between 1997 and 2001. References are given for spectral
types first and spectral indices next.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 88 21 Spectral types, near-infrared photometry, and
spectral indices of 21 K and M subdwarfs
refs.dat 65 13 References
table2.dat 51 21 Stellar parameters of the observed targets
sp/* . 21 Individual reduced UVES Spectrum
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See also:
J/AJ/113/806 : M-subdwarfs (Gizis 1997)
J/ApJS/190/100 : NIR proper motion survey using 2MASS (Kirkpatrick+, 2010)
J/MNRAS/373/705 : High proper motion stars optical spectroscopy (Reyle+, 2006)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- Name Name of the target
18- 19 I2 h RAh Right Ascension (J2000) (1)
21- 22 I2 min RAm Right Ascension (J2000) (1)
24- 27 F4.1 s RAs Right Ascension (J2000) (1)
29 A1 --- DE- Declination sign (J2000) (1)
30- 31 I2 deg DEd Declination (J2000) (1)
33- 34 I2 arcmin DEm Declination (J2000) (1)
36- 37 I2 arcsec DEs Declination (J2000) (1)
39- 45 A7 --- SpType MK spectral type
47- 51 F5.2 mag Jmag J magnitude (2MASS) (1)
53- 57 F5.2 mag Hmag H magnitude (2MASS) (1)
59- 63 F5.2 mag Ksmag Ks magnitude (2MASS) (1)
65- 69 F5.3 --- TiO5 ?=- TiO5 spectral index
71- 75 F5.3 --- CaH2 ?=- CaH2 spectral index
77- 81 F5.3 --- CaH3 ?=- CaH3 spectral index
83- 85 A3 --- r_SpType Reference for spectral type, in refs.dat file
87- 88 I2 --- r_TiO5 ? Reference for spectral indices,
in refs.dat file
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Note (1): The photometry and coordinates are taken from 2MASS,
between 1997 and 2001.
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Ref Reference code
4- 22 A19 --- BibCode BibCode
24- 43 A20 --- Aut Author's name
45- 65 A21 --- Com Comments
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- Name Name of the target
18- 24 A7 --- SpType MK spectral type
26- 29 I4 K Teff Effective temperature
31- 32 I2 K e_Teff Error on effective temperature
34- 36 F3.1 [cm/s2] logg Surface gravity
38- 41 F4.2 [cm/s2] e_logg Error on surface gravity
43- 46 F4.1 [-] [Fe/H] Metallicity
48- 51 F4.2 [-] e_[Fe/H] Error on metallicity
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Byte-by-byte Description of file: sp/*
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Bytes Format Units Label Explanations
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2- 18 F17.11 0.1nm lambda [6437/1025] Wavelength (Å)
20- 32 E13.7 cW/m2/nm Flux Flux (erg/s/Å/cm2)
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Acknowledgements:
Arvind Singh Rajpurohit, arvind(at)obs-besancon.fr
(End) Patricia Vannier [CDS] 27-Feb-2014