J/A+A/478/507 Distances and atmospheric parameters of MSU stars (Morales+, 2008)
The effect of activity on stellar temperatures and radii.
Morales J.C., Ribas I., Jordi C.
<Astron. Astrophys. 478, 507 (2008)>
=2008A&A...478..507M 2008A&A...478..507M
ADC_Keywords: Binaries, eclipsing ; Stars, late-type; Effective temperatures ;
Magnitudes
Keywords: stars: activity - stars: fundamental parameters - stars: late-type -
stars: binaries: eclipsing
Abstract:
Recent analyses of low-mass eclipsing binary stars have unveiled a
significant disagreement between the observations and the predictions
of stellar structure models. Results show that theoretical models
underestimate the radii and overestimate the effective temperatures of
low-mass stars but yield luminosities that accord with observations. A
hypothesis based upon the effects of stellar activity was put forward
to explain the discrepancies. Here we study the existence of the same
trend in single active stars and provide a consistent scenario to
explain systematic differences between active and inactive stars in
the H-R diagram reported earlier. The analysis is done using single
field stars of spectral types late-K and M and computing its
bolometric magnitudes and temperatures through infrared colours and
spectral indices. The properties of the stars in samples of active
and inactive stars are compared statistically to reveal systematic
differences. After accounting for a number of possible bias effects,
active stars are shown to be cooler than inactive stars of similar
luminosity therefore implying a larger radius as well, in proportions
that are in excellent agreement with those found from eclipsing
binaries. The present results generalise the existence of strong
radius and temperature dependences on stellar activity to the entire
population of low-mass stars, regardless of their membership in close
binary systems.
Description:
These tables list the fundamental properties of 747 stars with
trigonometric parallaxes determinations from the Palomar/Michigan
State University survey (hereafter PMSU; Reid et al. 1995; Hawley et
al. 1996, Cat. III/198).
For each of those stars its PMSU number, identifier, distance, TiO5
spectral index, equivalent width of the Hα line (EW Hα) if
active, K band magnitude and absolute bolometric magnitude are listed.
The final remark indicates if the star has been excluded from the
sample of single main sequence stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 54 675 List of inactive stars
table2.dat 54 72 List of active stars
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See also:
III/198 : Palomar/MSU nearby star spectroscopic survey (Hawley+ 1997)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/A+A/333/231 : O-M stars model atmospheres (Bessell+ 1998)
J/AJ/130/1871 : Spectroscopic survey of M dwarfs (Bochanski+, 2005)
Byte-by-byte Description of file: table?.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- [RHG95] Star PMSU number
6- 16 A11 --- OName Gliese or other identification
17- 22 F6.1 pc Dist Heliocentric distance
23- 28 F6.3 --- TiO5 TiO5 spectral index
29- 34 F6.3 0.1nm Halpha ? Hα equivalent width (only in table2)
35- 39 I5 K Teff ? Effective temperature (1)
40- 46 F7.3 mag Kmag ? K band magnitude (2)
47- 52 F6.2 mag Mbol ? Bolometric magnitude (3)
53- 54 I2 --- Rem ? Remarks (4)
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Note (1): Effective temperature is computed from de TiO5 spectral index
using its relation with the spectral type given in Reid et al.
(1995AJ....110.1838R 1995AJ....110.1838R, Cat. III/198). The Bessell (1991AJ....101..662B 1991AJ....101..662B)
scale of effective temperature vs. spectral type is then used to get
the Teff value.
Note (2): The magnitude in the K band is obtained from the 2MASS survey
catalog.
Note (3): The absolute bolometric magnitude is computed using Kmag and a
bolometric correction in the K band. The absolute K band magnitude is
obtained from Kmag and the distance given for each star in the PMSU
catalog. The bolometric correction is computed as a function of
effective temperature using the models in Bessell et al. (1998,
Cat. J/A+A/333/231).
Note (4): Remarks for the excluded stars from the sample of single main
sequence stars are as follows:
1 = Stars in associations and moving groups with ages less than 200Myrs
2 = Stars excluded using the common criteria of halo stars kinematics
3 = Subdwarfs excluded using the relation between TiO5 and CaH2
spectral indices found by Bochanski et al. (2005, J/AJ/130/1871)
4 = Binary or multiple systems
5 = Insufficient or bad data
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Acknowledgements:
Juan Carlos Morales, moralesieec.uab.es
(End) Juan Carlos Morales [IEEC, Spain], Patricia Vannier [CDS] 30-Nov-2007