| Issue |
A&A
Volume 565, May 2014
|
|
|---|---|---|
| Article Number | A63 | |
| Number of page(s) | 31 | |
| Section | Stellar atmospheres | |
| DOI | https://doi.org/10.1051/0004-6361/201323167 | |
| Published online | 13 May 2014 | |
A new method for an objective, χ2-based spectroscopic analysis of early-type stars⋆,⋆⋆
First results from its application to single and binary B- and late O-type stars
1
Dr. Karl Remeis-Observatory & ECAP, Astronomical Institute,
Friedrich-Alexander University Erlangen-Nuremberg, Sternwartstr. 7, 96049
Bamberg, Germany
e-mail: andreas.irrgang@fau.de
2
Institut für Astro- und Teilchenphysik, Universität
Innsbruck, Technikerstr.
25/8, 6020
Innsbruck,
Austria
3
Max-Planck Institut für Radioastronomie,
Auf dem Hügel 69, 53121
Bonn,
Germany
4
Universitätssternwarte München, Scheinerstr. 1, 81679
München,
Germany
Received:
2
December
2013
Accepted:
5
March
2014
Context. A precise quantitative spectral analysis, encompassing atmospheric parameter and chemical elemental abundance determination, is time-consuming due to its iterative nature and the multi-parameter space to be explored, especially when done by the naked eye.
Aims. A robust automated fitting technique that is as trustworthy as traditional methods would allow for large samples of stars to be analyzed in a consistent manner in reasonable time.
Methods. We present a semi-automated quantitative spectral analysis technique for early-type stars based on the concept of χ2 minimization. The method’s main features are as follows: far less subjectivity than the naked eye, correction for inaccurate continuum normalization, consideration of the whole useful spectral range, and simultaneous sampling of the entire multi-parameter space (effective temperature, surface gravity, microturbulence, macroturbulence, projected rotational velocity, radial velocity, and elemental abundances) to find the global best solution, which is also applicable to composite spectra.
Results. The method is fast, robust, and reliable as seen from formal tests and from a comparison with previous analyses.
Conclusions. Consistent quantitative spectral analyses of large samples of early-type stars can be performed quickly with very high accuracy.
Key words: binaries: spectroscopic / methods: data analysis / stars: early-type / stars: fundamental parameters / stars: general / stars: abundances
Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under program IDs 074.D-0021(A), 088.A-9003(A), and 091.C-0713(A). Based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias, proposal 41-027.
Figures 2 and 3 are available in electronic form at http://www.aanda.org
© ESO, 2014
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