J/A+A/708/L17 HD 140283 and BPS CS 29502-0092 equivalent widths (Heil+, 2026)
Comparison of spectroscopic and photometric stellar parameter determination in
carbon-enhanced metal-poor stars.
Heil S., Hansen C.J.
<Astron. Astrophys. 708, L17 (2026)>
=2026A&A...708L..17H 2026A&A...708L..17H (SIMBAD/NED BibCode)
ADC_Keywords: Stars, metal-deficient ; Equivalent widths ; Spectroscopy ;
Optical
Keywords: techniques: photometric - techniques: spectroscopic -
stars: atmospheres - stars: carbon - stars: fundamental parameters
Abstract:
The aim of this study is to evaluate the reliability of spectroscopic
and photometric approaches for deriving stellar parameters in
metal-poor stars, focusing on a carbon-enhanced metal-poor (CEMP) star
with a well-studied very metal-poor star as reference.
The determination of stellar parameters is first based on
spectroscopy, where parameters are derived from Fe line equivalent
widths using the 1D local thermodynamical equilibrium (LTE) synthesis
code pyMOOGi. The second approach is based on photometry, employing
colour-Teff relations, Gaia parallaxes, and bolometric corrections.
Analyses of the two stars reveal systematic discrepancies: photometric
Teff, log(g), and [Fe/H] are higher than spectroscopic values. Offsets
exceed uncertainties, mainly due to the limited Fe II line set and
non-LTE effects in spectroscopy. Photometric based parameters prove
more consistent and reliable, particularly when using (V-K) or (BP-K)
colours.
These findings confirm previous results and demonstrate that
photometric methods yield more reliable stellar parameters, especially
for CEMP stars than 1D LTE spectroscopic methods.
Description:
Table A.1: Linelist including wavelength, excitation potential,
oscillator strength, and equivalent widths for HD 140283 (EW-HD) and
BPS CS 29502-0092 (EW-BPS), together with the corresponding references.
Objects:
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RA (2000) DE Designation(s)
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15 43 03.09 -10 56 00.5 HD 140283 = TIC 290565106
22 22 35.99 -01 38 27.6 BPS CS 29502-0092 = TIC 439856068
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 51 161 Line list
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 8 F8.3 0.1nm lambda lambda (Angstroem)
10- 13 F4.1 --- El Atomic number (e.g., 26.0 = Fe I)
15- 18 F4.2 eV chi chi
20- 25 F6.3 [-] loggf Logarithm of oscillator strength
27- 32 F6.2 0.1pm EW-HD Equivalent width in HD 140283 (milli Angstroem)
34- 39 F6.2 0.1pm EW-BPS ?=-9.99 Equivalent width in BPS CS 29502-0092
(milli Angstroem)
41- 43 A3 --- LineRef Reference for equivalent width measurements (1)
48- 51 A4 --- AtomRef Atomic data reference (2)
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Note (1): Reference for equivalent width measurements as follows:
(a) = Siqueira-Mello et al., 2015A&A...584A..86S 2015A&A...584A..86S, Cat. J/A+A/584/A86
(b) = Spite et al., 2013A&A...552A.107S 2013A&A...552A.107S
(c) = Hansen et al., 2011A&A...527A..65H 2011A&A...527A..65H
(d) = Aoki et al., 2007ApJ...655..492A 2007ApJ...655..492A, Cat. J/ApJ/655/482
(e) = Hansen et al., 2019A&A...623A.128H 2019A&A...623A.128H, Cat. J/A+A/623/A128
(f) = National Institute of Standards and Technology (NIST)
(g) = Melendez & Barbuy, 2009A&A...497..611M 2009A&A...497..611M
Note (2): The atomic data reference as follows:
(1) = Blackwell et al., 1979MNRAS.186..657B 1979MNRAS.186..657B
(2) = O'Brian et al., 1991JOSAB...8.1185O 1991JOSAB...8.1185O
(3) = Blackwell et al., 1982MNRAS.201..595B 1982MNRAS.201..595B
(4) = Blackwell et al., 1980MNRAS.191..445B 1980MNRAS.191..445B
(5) = Bridges & Kornblith, 1974ApJ...192..793B 1974ApJ...192..793B
(6) = Bard et al., 1994A&A...282.1014B 1994A&A...282.1014B
(7) = Bard & Kock, 1991A&A...248..315B 1991A&A...248..315B
(8) = Melendez & Barbuy, 2009A&A...497..611M 2009A&A...497..611M
(9) = Raassen & Uylings, 1998JPhB...31.3137R 1998JPhB...31.3137R
(10) = Schnabel et al., 2004A&A...414.1169S 2004A&A...414.1169S
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Acknowledgements:
Svenja Heil, svenja.he25(at)gmail.com
(End) Svenja Heil [Univ. Frankfurt], Patricia Vannier [CDS] 23-Feb-2026