Exploration of the BaSeL stellar library for 9 F-type stars COROT potential targets

Free access article

Issue		A&A Volume 365, Number 3, January III 2001


Page(s)		535 - 544
Section		Stellar atmospheres
DOI		http://dx.doi.org/10.1051/0004-6361:20000190

A&A 365, 535-544 (2001)
DOI: 10.1051/0004-6361:20000190

Comparisons of fundamental stellar parameter determinations

E. Lastennet^{1, 2}, F. Lignières^{1, 3}, R. Buser⁴, Th. Lejeune⁵, Th. Lüftinger⁶, F. Cuisinier² and C. van't Veer-Menneret⁷

¹ Astronomy Unit, Queen Mary and Westfield College, Mile End Road, London E1 4NS, UK
² Depto. de Astronomia, UFRJ, Ladeira Pedro Antônio 43, 20080-090 Rio de Janeiro RJ, Brazil
³ Laboratoire d'Astrophysique, CNRS UMR 5572, Obs. Midi-Pyrénées, 57 avenue d'Azereix, 65008 Tarbes Cedex, France
⁴ Astronomisches Institut der Universität Basel, Venusstr. 7, 4102 Binningen, Switzerland
⁵ Observatório Astronómico de Coimbra, Santa Clara, 3040 Coimbra, Portugal
⁶ Institut für Astronomie, Universität Wien, Türkenschanzstr. 17, 1180 Wien, Austria
⁷ Observatoire de Paris, 61 avenue de l'Observatoire, 75014 Paris, France

(Received 13 April 2000 / Accepted 19 October 2000 )

Abstract
The Basel Stellar Library (BaSeL models) is constituted of the merging of various synthetic stellar spectra libraries, with the purpose of giving the most comprehensive coverage of stellar parameters. It has been corrected for systematic deviations detected in respect to UBVRIJHKLM photometry at solar metallicity, and can then be considered as the state-of-the-art knowledge of the broad band content of stellar spectra. In this paper, we consider a sample of 9 F-type stars with detailed spectroscopic analysis to investigate the Basel Stellar Library in two photometric systems simultaneously, Johnson (B-V, U-B) and Strömgren (b-y, m₁, and c₁). The sample corresponds to potential targets of the central seismology programme of the COROT space experiment, which have been recently observed at OHP. The atmospheric parameters $T_{\rm eff}$ , [Fe/H], and log g obtained from the BaSeL models are compared with spectroscopic determinations as well as with results of other photometric calibrations. For a careful interpretation of the BaSeL solutions, we computed confidence regions around the best $\chi$ ²-estimates and projected them on $T_{\rm eff}$ -[Fe/H], $T_{\rm eff}$ -log g, and log g-[Fe/H] diagrams. We first derive the 3 atmospheric parameters from the full photometric information available (Johnson and Strömgren data). The BaSeL library has only been calibrated for broad band UBVRIJHKLM photometry, and it presents therefore intrinsic limitations in respect to other photometric systems, especially with different bandwidth. Thus, using this combination (Johnson and Strömgren), BaSeL temperatures are systematically lower ( $\sim$ 130 K), and the discrepancy for the gravity and the metallicity can be quite large in comparison to the other methods. To disentangle these unexpected discrepancies, we fixed the temperatures at their spectroscopic values and studied the relative influence of each colour index in the log g-[Fe/H] diagrams. We find inconsistent results between Strömgren and Johnson synthetic colours. While the Johnson colours give impressively good log g-[Fe/H] solutions, the combination of the m₁ and c₁ Strömgren synthetic indices does not provide reliable results. This is not, of course, due to any intrinsic superiority of the UBV over the Strömgren system, but to the properties of the BaSeL models. Finally, in order to simultaneously and accurately determine the stellar parameters $T_{\rm eff}$ , [Fe/H] and log g, we suggest to use the combination of the synthetic BaSeL indices B-V, U-B and b-y rather than B-V, U-B, b-y, m₁ and c₁.

Key words: stars: fundamental parameters -- stars: abundances -- surveys

Offprint request: E. Lastennet

SIMBAD Objects

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.