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Unveiling systematic biases in the 1D LTE excitation-ionization balance of Fe for FGK stars: a novel approach to determination of stellar parameters

Ruchti, Gregory LU ; Bergemann, Maria; Serenelli, Aldo; Casagrande, Luca and Lind, Karin (2013) In Monthly Notices of the Royal Astronomical Society 429(1). p.126-134
Abstract
We present a comprehensive analysis of different techniques available for the spectroscopic analysis of FGK stars and provide a recommended methodology which efficiently estimates accurate stellar atmospheric parameters for large samples of stars. Our analysis includes a simultaneous equivalent width analysis of Fe I and Fe II spectral lines, and for the first time, utilizes on-the-fly non-local thermodynamic equilibrium (NLTE) corrections of individual Fe I lines. We further investigate several temperature scales, finding that estimates from Balmer line measurements provide the most accurate effective temperatures at all metallicities. We apply our analysis to a large sample of both dwarf and giant stars selected from the Radial Velocity... (More)
We present a comprehensive analysis of different techniques available for the spectroscopic analysis of FGK stars and provide a recommended methodology which efficiently estimates accurate stellar atmospheric parameters for large samples of stars. Our analysis includes a simultaneous equivalent width analysis of Fe I and Fe II spectral lines, and for the first time, utilizes on-the-fly non-local thermodynamic equilibrium (NLTE) corrections of individual Fe I lines. We further investigate several temperature scales, finding that estimates from Balmer line measurements provide the most accurate effective temperatures at all metallicities. We apply our analysis to a large sample of both dwarf and giant stars selected from the Radial Velocity Experiment (RAVE) survey. We then show that the difference between parameters determined by our method and that by the standard 1D LTE excitation-ionization balance of Fe reveals substantial systematic biases: up to 400 K in effective temperature, 1.0 dex in surface gravity and 0.4 dex in metallicity for stars with [Fe/H] similar to -2.5. This has large implications for the study of the stellar populations in the Milky Way. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
stars: abundances, stars: late-type, stars: Population II, radiative, transfer, methods: data analysis, techniques: spectroscopic
in
Monthly Notices of the Royal Astronomical Society
volume
429
issue
1
pages
126 - 134
publisher
Oxford University Press (OUP)
external identifiers
  • wos:000318238300033
  • scopus:84873924695
ISSN
1365-2966
DOI
10.1093/mnras/sts319
language
English
LU publication?
yes
id
b3509b14-aa8c-498b-a744-40b85e754326 (old id 3815536)
date added to LUP
2013-06-25 15:51:26
date last changed
2019-08-07 01:17:24
@article{b3509b14-aa8c-498b-a744-40b85e754326,
  abstract     = {We present a comprehensive analysis of different techniques available for the spectroscopic analysis of FGK stars and provide a recommended methodology which efficiently estimates accurate stellar atmospheric parameters for large samples of stars. Our analysis includes a simultaneous equivalent width analysis of Fe I and Fe II spectral lines, and for the first time, utilizes on-the-fly non-local thermodynamic equilibrium (NLTE) corrections of individual Fe I lines. We further investigate several temperature scales, finding that estimates from Balmer line measurements provide the most accurate effective temperatures at all metallicities. We apply our analysis to a large sample of both dwarf and giant stars selected from the Radial Velocity Experiment (RAVE) survey. We then show that the difference between parameters determined by our method and that by the standard 1D LTE excitation-ionization balance of Fe reveals substantial systematic biases: up to 400 K in effective temperature, 1.0 dex in surface gravity and 0.4 dex in metallicity for stars with [Fe/H] similar to -2.5. This has large implications for the study of the stellar populations in the Milky Way.},
  author       = {Ruchti, Gregory and Bergemann, Maria and Serenelli, Aldo and Casagrande, Luca and Lind, Karin},
  issn         = {1365-2966},
  keyword      = {stars: abundances,stars: late-type,stars: Population II,radiative,transfer,methods: data analysis,techniques: spectroscopic},
  language     = {eng},
  number       = {1},
  pages        = {126--134},
  publisher    = {Oxford University Press (OUP)},
  series       = {Monthly Notices of the Royal Astronomical Society},
  title        = {Unveiling systematic biases in the 1D LTE excitation-ionization balance of Fe for FGK stars: a novel approach to determination of stellar parameters},
  url          = {http://dx.doi.org/10.1093/mnras/sts319},
  volume       = {429},
  year         = {2013},
}