J/A+A/575/A26 Properties of the Population II star HD 140283 (Creevey+, 2015)
Benchmark stars for Gaia: Fundamental properties of the Population II star
HD 140283 from interferometric, spectroscopic, and photometric data.
Creevey O.L., Thevenin F., Berio P., Heiter U., von Braun K., Mourard D.,
Bigot L., Boyajian T.S., Kervella P., Morel P., Pichon B., Chiavassa A.,
Nardetto N., Perraut K., Meilland A., Mc Alister H.A., ten Brummelaar T.A.,
Farrington C., Sturmann J., Sturmann L., Turner N.
<Astron. Astrophys. 575, A26 (2015)>
=2015A&A...575A..26C 2015A&A...575A..26C
ADC_Keywords: Stars, population II ; Models ; Stars, ages
Keywords: stars: fundamental parameters - stars: Population II -
techniques: interferometric - techniques: spectroscopic - surveys -
stars: individual HD 140283
Abstract:
Metal-poor halo stars are important astrophysical laboratories that
allow us to unravel details about many aspects of astrophysics,
including the chemical conditions at the formation of our Galaxy,
understanding the processes of diffusion in stellar interiors, and
determining precise effective temperatures and calibration of
colour-effective temperature relations. To address any of these issues
the fundamental properties of the stars must first be determined.
HD 140283 is the closest and brightest metal-poor Population II halo
star (distance = 58pc and V=7.21), an ideal target that allows us
to approach these questions, and one of a list of 34 benchmark stars
defined for Gaia astrophysical parameter calibration. In the framework
of characterizing these benchmark stars, we determined the fundamental
properties of HD 140283 (radius, mass, age, and effective temperature)
by obtaining new interferometric and spectroscopic measurements and
combining them with photometry from the literature. The
interferometric measurements were obtained using the visible
interferometer VEGA on the CHARA array and we determined a 1D
limb-darkened angular diameter of θ1D=0.353±0.013-milliarcsec.
Description:
Table 12 contains all of the combinations of model stellar properties
of HD 140283. The age of HD 140283 and the corresponding mixing-length
parameter, alpha, is given as a function of mass, initial helium mass
fraction Yi and total absorption between the Earth and the star AV
(mag). The last column indicates if the age and α come from a
calculated evolution model (M) or from equations 11 and 12
(I = interpolated). The calculated models are used to obtain the
coefficients for equations 11 and 12. For the 'I' results, only a
valid range is given i.e. age<14.5Gyr and 0.5<α<1.5.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
15 43 03.10 -10 56 00.6 HD 140283 = HIP 76976
----------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table12.dat 34 157 Combinations of model stellar properties of the
star HD 140283
--------------------------------------------------------------------------------
See also:
I/324 : The Initial Gaia Source List (IGSL) (Smart, 2013)
VI/137 : GaiaSimu Universe Model Snapshot (Robin+, 2012)
J/A+A/564/A133 : Gaia FGK benchmark stars: metallicity (Jofre+, 2014)
J/A+A/565/A11 : Gaia photometry for white dwarfs (Carrasco+, 2014)
J/A+A/566/A98 : The Gaia Benchmark Stars - Library (Blanco-Cuaresma+, 2014)
J/A+A/548/A42 : HD 140283 average spectrum (370-1040nm) (Siqueira Mello+ 2012)
Byte-by-byte Description of file: table12.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 F5.3 Msun Mass [0.77/0.83] Adopted mass of HD140283
8- 12 F5.3 --- Yi [0.245/0.26] Adopted initial helium mass fraction
(Yi)
15- 18 F4.2 mag AV [0/0.1] Adopted total absorption (AV)
21- 25 F5.2 Gyr Age [9.91/14.29] Age of HD140283 for the adopted
values of Mass, Yi and AV
28- 31 F4.2 --- alpha [0.42/1.45] Corresponding mixing-length parameter
α
34 A1 --- M/I [M/I] Result of Model, or Interpolation (1)
--------------------------------------------------------------------------------
Note (1): Flag as follows:
M = a stellar evolution model was calculated
I = the parameters were derived from eqs. 11 and 12 (I for interpolated)
--------------------------------------------------------------------------------
Acknowledgements:
Orlagh Creevey, orlagh.creevey(at)ias.u-psud.fr
(End) Patricia Vannier [CDS] 10-Dec-2014