J/A+A/658/A47 Dwarf stars limb-darkening coefficients (Karovicova+, 2022)
Fundamental stellar parameters of benchmark stars from CHARA interferometry.
II. Dwarf stars.
Karovicova I., White T.R., Nordlander T., Casagrande L., Ireland M.,
Huber D.
<Astron. Astrophys. 658, A47 (2022)>
=2022A&A...658A..47K 2022A&A...658A..47K (SIMBAD/NED BibCode)
ADC_Keywords: Stars, dwarfs ; Models, atmosphere
Keywords: standards - techniques: interferometric - surveys - stars: general
Abstract:
Stellar models applied to large stellar surveys of the Milky Way need
to be properly tested against a sample of stars with highly reliable
fundamental stellar parameters. We have established a program aiming
to deliver such a sample of stars. Here we present new fundamental
stellar parameters of nine dwarf stars that will be used as benchmark
stars for large stellar surveys. One of these stars is the solar-twin
18Sco, which is also one of the Gaia-ESO benchmarks. The goal is to
reach a precision of 1% in effective temperatures (Teff). This
precision is important for accurate determinations of the full set of
fundamental parameters and abundances of stars observed by the
surveys. We observed HD131156 (xi Boo), HD146233 (18 Sco), HD152391,
HD173701, HD185395 (theta Cyg), HD186408 (16 Cyg A), HD186427
(16 Cyg B), HD190360 and HD207978 (15 Peg) using the high angular
resolution optical interferometric instrument PAVO at the CHARA Array.
We derived limb-darkening corrections from 3D model atmospheres and
determined Teff directly from the Stefan-Boltzmann relation, with an
iterative procedure to interpolate over tables of bolometric
corrections. Surface gravities were estimated from comparisons to
Dartmouth stellar evolution model tracks. We collected spectroscopic
observations from the ELODIE spectrograph and estimated metallicities
([Fe/H]) from a 1D non-local thermodynamic equilibrium (NLTE)
abundance analyses of unblended lines of neutral and singly ionized
iron. For eight of the nine stars we measure the Teff less than 1%,
and for one star better than 2%. We determined the median
uncertainties in log g and [Fe/H] as 0.015dex and 0.05dex,
respectively. This study presents updated fundamental stellar
parameters of nine dwarf stars that can be used as new set of
benchmarks. All fundamental stellar parameters were based on
consistently combining interferometric observations, 3D limb-darkening
modelling and spectroscopic analysis. The next paper in this series
will extend our sample to giants in the metal-rich 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 et al.,
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
stars.dat 32 9 Target stars
tables.dat 61 342 Angular diameters and limb-darkening coefficients
for 9 dwarf stars (tables A1-A9)
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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/A48 : 7 giants/subgiants limb-darkening coefficients
(Karovicova, 2022)
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Star name
10- 11 I2 h RAh Simbad right ascension (J2000.0)
13- 14 I2 min RAm Simbad right ascension (J2000.0)
16- 20 F5.2 s RAs Simbad right ascension (J2000.0)
22 A1 --- DE- Simbad declination sign (J2000.0)
23- 24 I2 deg DEd Simbad declination (J2000.0)
26- 27 I2 arcmin DEm Simbad declination (J2000.0)
29- 32 F4.1 arcsec DEs Simbad declination (J2000.0)
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Byte-by-byte Description of file: tables.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Star name
10- 11 I2 --- Ch [1/38] Channel number
13- 18 F6.4 --- a1 Limb darkening coefficient a1 (1)
20- 28 F9.7 --- a2 Limb darkening coefficient a2 (1)
30- 39 F10.7 --- a3 Limb darkening coefficient a3 (1)
41- 50 F10.7 --- a4 Limb darkening coefficient a3 (1)
52- 61 F10.7 mas theta Angular diameter
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Note (1): Limb-darkening coefficients derived from the grid of Magic et al.,
2015, 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 III 2022A&A...658A..48K 2022A&A...658A..48K, Cat. J/A+A/658/A48
(End) Patricia Vannier [CDS] 13-Sep-2021