J/A+A/658/A48 7 giants/subgiants limb-darkening coefficients (Karovicova, 2022)
Fundamental stellar parameters of benchmark stars from CHARA interferometry.
III. Giant and subgiant stars.
Karovicova I., White T.R., Nordlander T., Casagrande L., Ireland M.,
Huber D.
<Astron. Astrophys. 658, A48 (2022)>
=2022A&A...658A..48K 2022A&A...658A..48K (SIMBAD/NED BibCode)
ADC_Keywords: Stars, giant ; Models, atmosphere
Keywords: standards - techniques: interferometric - surveys -
Abstract:
Large spectroscopic surveys of the Milky Way need to be calibrated
against a sample of benchmark stars to ensure the reliable
determination of atmospheric parameters. Here we present new
fundamental stellar parameters of seven giant and subgiant stars that
will serve as benchmark stars for large surveys. The aim is to reach a
precision of 1% in the effective temperature. This precision is
essential for accurate determinations of the full set of fundamental
parameters and abundances of stars observed by the stellar surveys. We
observed HD121370 (eta Boo), HD161797 (mu Her), HD175955, HD182736,
HD185351, HD188512 (beta Aql), and HD189349 using the high angular
resolution optical interferometric instrument PAVO at the CHARA Array.
The limb-darkening corrections were determined from 3D model
atmospheres based on the STAGGER grid. The Teff were determined
directly from the Stefan-Boltzmann relation, with an iterative
procedure to interpolate over tables of bolometric corrections. We
estimated surface gravities from comparisons to Dartmouth stellar
evolution model tracks. The spectroscopic observations were collected
from the ELODIE and FIES spectrographs. We estimated metallicities
([Fe/H]) from a 1D non-local thermodynamic equilibrium (NLTE)
abundance analysis of unblended lines of neutral and singly ionised
iron. For six of the seven stars we measure Teff to better than 1%.
For one star, HD189349, the uncertainty in Teff is 2% due to an
uncertain bolometric flux. We do not recommend this star as a
benchmark until this measurement can be improved. Median uncertainties
for all stars in logg and [Fe/H] are 0.034dex and 0.07dex,
respectively. This study presents updated fundamental stellar
parameters of seven giant and subgiant stars that can be used as a new
set of benchmarks. All the fundamental stellar parameters were based
on consistently combining interferometric observations, 3D
limb-darkening modelling and spectroscopic analysis. This paper in
this series follows our previous papers including dwarf stars and
stars in the metal-poor range.
Description:
Limb-darkening coefficients derived for the target stars using the 3D
STAGGER-grid (Magic et al., 2015A&A...573A..90M 2015A&A...573A..90M, Cat. J/A+A/573/A90).
The coefficients a1, a2, a3, and a4 appearing in Eq. 7 of Magic et al.
(2015A&A...573A..90M 2015A&A...573A..90M) are provided for each star, in 38 observed
channels of the PAVO instrument at the CHARA array (Ireland+, 2008,
Proc. SPIE, 701324). See Sect. 3.1 of the paper for further details.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 89 7 Stellar parameters
tablea.dat 44 266 Angular diameters and limb-darkening coefficients
(tables A1-A7)
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See also:
J/A+A/573/A90 : STAGGER-grid of 3D stellar models. IV. (Magic+, 2015)
J/A+A/640/A25 : Metal-poor stars limb-darkening coefficients
(Karovicova+, 2020)
J/A+A/658/A47 : Dwarf stars limb-darkening coefficients (Karovicova+, 2022)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Star name
10- 17 A8 --- OName Other name
19- 26 A8 --- SpType Spectral type
28- 29 I2 h RAh Right ascension (J2000)
31- 32 I2 min RAm Right ascension (J2000)
34- 40 F7.4 s RAs Right ascension (J2000)
42 A1 --- DE- Declination sign (J2000)
43- 44 I2 deg DEd Declination (J2000)
46- 47 I2 arcmin DEm Declination (J2000)
49- 55 F7.4 arcsec DEs Declination (J2000)
57- 60 F4.2 mag Vmag V magnitude
62- 65 F4.2 mag gmag g magnitude
67- 70 F4.2 mag E(B-V) Redenning
72- 75 F4.2 mag e_E(B-V) Redenning error
77- 83 F7.3 mas Plx Gaia DR2 parallax without any zero point
correction
85- 89 F5.3 mas e_Plx Gaia DR2 parallax error
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Byte-by-byte Description of file: tablea.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Star name
10- 11 I2 --- Chan [1/38] Channel number
13- 18 F6.4 um lambda Wavelength
20- 24 F5.3 --- a1 Limb-darkening coefficient a1 (1)
26- 31 F6.3 --- a2 Limb-darkening coefficient a2 (1)
33- 37 F5.3 --- a3 Limb-darkening coefficient a3 (1)
39- 44 F6.3 --- a4 Limb-darkening coefficient a4 (1)
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Note (1): Limb-darkening coefficients derived from the grid of Magic et al.,
2015A&A...573A..90M 2015A&A...573A..90M, Cat. J/A+A/573/A90; see text for details.
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Acknowledgements:
Iva Karovicova, karovicova(at)uni-heidelberg.de
References:
Karovicova et al., Paper I 2020A&A...640A..25K 2020A&A...640A..25K, Cat. J/A+A/640/A25
Karovicova et al., Paper II 2022A&A...658A..47K 2022A&A...658A..47K, Cat. J/A+A/658/A47
(End) Patricia Vannier [CDS] 14-Oct-2021