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E. Solano,
C. Catala,
R. Garrido,
E. Poretti,
E. Janot-Pacheco,
R. Gutiérrez,
R. González,
L. Mantegazza,
C. Neiner,
Y. Fremat, [......],
V. Costa,
A. Rolland,
E. Antonello,
M. Bossi,
A. Buzzoni,
C. Rodrigo,
C. Aerts,
C. J. Butler,
E. Guenther,
and A. Hatzes
[show abstract]
[hide abstract]
ABSTRACT: The GAUDI database (Ground-based Asteroseismology Uniform Database Interface) is a preparatory archive for the COROT (Convection, Rotation, and Planetary Transits) mission developed at the Laboratorio de Astrofísica Espacial y Física Fundamental (Laboratory for Space Astrophysics and Theoretical Physics, Spain). Its intention is to make the ground-based observations obtained in preparation of the asteroseismology program available in a simple and efficient way. It contains spectroscopic and photometric data together with inferred physical parameters for more than 1500 objects gathered since 1998 January 1998 in 6 years of observational campaigns. In this paper, the main functions and characteristics of the system are described.
The Astronomical Journal 12/2007; 129(1):547. · 4.03 Impact Factor
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H. Bruntt,
I. F. Bikmaev,
C. Catala,
E. Solano,
M. Gillon,
P. Magain,
C. Van't Veer-Menneret,
Ch. Stuetz,
W. W. Weiss,
D. Ballereau,
J. -C. Bouret,
S. Charpinet,
T. Hua, D Katz,
F. Lignieres,
T. Lueftinger
[show abstract]
[hide abstract]
ABSTRACT: One of the goals of the ground-based support program for the COROT and Roemer satellite missions is to characterize suitable target stars for the part of the missions dedicated to asteroseismology. We present the detailed abundance analysis of nine of the potential COROT main targets using the semi-automatic software VWA. For two additional COROT targets we could not perform the analysis due to the high rotational velocity of these stars. For five stars with low rotational velocity we have also performed abundance analysis by a classical equivalent width method in order to test the reliability of the VWA software. The agreement between the different methods is good. We find that it is necessary to measure abundances extracted from each line relative to the abundances found from a spectrum of the Sun in order to remove systematic errors. We have constrained the global atmospheric parameters Teff, log g, and [Fe/H] to within 70-100 K, 0.1-0.2 dex, and 0.1 dex for five stars which are slow rotators (v sin i < 15 km/s). For most of the stars stars we find good agreement with the parameters found from line depth ratios, H-alpha lines, Str\"omgren indices, previous spectroscopic studies, and also log g determined from the HIPPARCOS parallaxes. For the fast rotators v sin i > 60 km/s it is not possible to constrain the atmospheric parameters. Comment: 14 pages, 6 figures, accepted 11th of June 2004 by A&A
03/2004;
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C. Catala,
J.-C. Bouret,
J. Butler,
R. Garrido,
F. Lignieres,
I. Roxburgh,
T. Lueftinger,
C. Soubiran, D. Katz,
C. van't Veer,
D. Ballereau,
T. Hua
[show abstract]
[hide abstract]
ABSTRACT: We have started a ground-based effort to determine the fundamental
parameters (Teff, log g, Fe/H, vsini, etc...) of 1,100
potential targets of the COROT central and exploratory asteroseismology
programmes. We are setting up a database of high (35,000 - 40,000)
resolution echelle spectra and Stromgren photometric data for all of
these stars. We use echelle spectrographs at OHP (France), Sutherland
(South Africa) and La Palma (Canary Islands), as well as a
semi-automatic photometric telescope near Granada (Spain). We intend to
gather all of these data, as well as the determined parameters and
characteristics, in a single database accessible by the community.
03/2000; -1:37.
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[show abstract]
[hide abstract]
ABSTRACT: We present a method estimating the atmospheric parameters Teff, log g, [Fe/H] for stars observed, even at low signal to noise ratio, with the echelle spectrograph ELODIE on the 193cm telescope at Observatoire de Haute-Provence. The method relies on the least-square comparison of the spectrum of a target star to a library of 211 spectra of reference stars for which the atmospheric parameters are well known and which were observed with the same instrument. In order to obtain a meaningful comparison between target and reference spectra, all features which are not intrinsic to the objects must be removed. This treatment involves the correction of the blaze efficiency for each order, cosmic rays hits and telluric line removal, convolution of the spectra to a common spectral resolution, wavelength scale and flux level adjustment. The library available at the present time covers the effective temperature range [4000K, 6300K], the metallicity range [-2.9, +0.35] and the gravities of both unevolved and evolved stars existing at these temperatures and metallicities. Tests performed with the actual library allow us to estimate the internal accuracy to be 86 K, 0.28 dex and 0.16 dex for Teff, log g, [Fe/H] for a target star with S/N = 100 and 102 K, 0.29 dex and 0.17 dex at S/N = 10. This accuracy will improve in the future as the number of reference stars in the library will increase. The software (named TGMET) has been installed at Observatoire de Haute-Provence for the on-line analysis of the high-resolution spectra of ELODIE, which was originally conceived for accurate radial velocity measurements.
07/1998;
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[show abstract]
[hide abstract]
ABSTRACT: A library of 211 echelle spectra taken with ELODIE at the Observatoire de Haute-Provence is presented. It provides a set of spectroscopic standards covering the full range of gravities and metallicities in the effective temperature interval [4000 K, 6300 K]. The spectra are straightened, wavelength calibrated, cleaned of cosmic ray hits, bad pixels and telluric lines. They cover the spectral range [440 nm, 680 nm] with an instrumental resolution of 42000. For each star, basic data were compiled from the Hipparcos catalogue and the Hipparcos Input Catalogue. Radial velocities with a precision better than 100 m/s are given. Atmospheric parameters (Teff, log g, [Fe/H]) from the literature are discussed. Because of scattered determinations in the bibliography, even for the most well-known stars, these parameters were adjusted by an iterative process which takes account of common or different spectral features between the standards, using our homogeneous set of spectra. Revised values of (Teff, log g, [Fe/H]) are proposed. They are still consistent with the literature, and also lead to the self-consistency of the library, in the sense that similar spectra have similar atmospheric parameters. This adjustment was performed by using step by step a method based on the least square comparison of carefully prepared spectra, which was originally developed for the on-line estimation of the atmospheric parameters of faint field stars (companion paper in the main journal). The spectra and corresponding data will only be available in electronic form at the CDS (ftp cdsarc.u-strasbg.fr or http://cdsweb.u-strasbg.fr/Abstract.html). Comment: 7 pages, 7 figures, accepted for publication in A&A Supplement Series
06/1998;
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[show abstract]
[hide abstract]
ABSTRACT: We show how previous works (Fuhrmann et al., van 't Veer-Menneret & Megessier) demonstrate the efficiency of the use of Balmer line profiles for effective temperature determination. In agreement with them, we insist on the physical interest of this method based on the behaviour of these lines with the variations of the parameters involved in the treatment of the convective transport. The comparison between Fuhrmann's results and ours, independently obtained, exhibits a quite good agreement. We show new results of effective temperature, gravity and metallicities for a few of our programme stars, ranging from solar to overabundant metallicities.
06/1998;
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[show abstract]
[hide abstract]
ABSTRACT: By the use of model atmospheres fluxes computed with Kurucz's ATLAS9 code, we have investigated the behaviour of the computed bolometric correction of the Hipparcos Hp band, namely BCHp = m bol Gamma Hp, with the basic physical parameters effective temperature, gravity and metallicity. The theoretical relations of BCHp versus effective temperature(T eff ) are compared to empirical ones. Key words: bolometric correction. 1. INTRODUCTION It is well recognised that the Hipparcos photometric band Hp would be a better choice than the Johnson V magnitude for making use of a bolometric correction, on the grounds that (i) the Hp band is very wide, and therefore a better approximation of the total flux than the V band, and (ii) it is measured with a greater accuracy for most Hipparcos stars (see, e.g. Lampens et al. 1997). In this way we would consider the use of: BCHp = m bol Gamma Hp (1) instead of: BCV = m bol Gamma V (2) For this purpose, we have undertaken an extensive computation o...
08/1997;
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[show abstract]
[hide abstract]
ABSTRACT: We present several new sets of grids of model stellar atmospheres computed with modified versions of the ATLAS9 code. Each individual set consists of several grids of models with different metallicities ranging from [M/H] = 2.0 to +1.0 dex. The grids range from 4000 to 10 000 K in T-eff and from 2.0 to 5.0 dex in log g. The individual sets differ from each other and from previous ones essentially in the physics used for the treatment of the convective energy transport, in the higher vertical resolution of the atmospheres and in a finer grid in the (T-eff, log g) plane. These improvements enable the computation of derivatives of color indices accurate enough for pulsation mode identification. In addition, we show that the chosen vertical resolution is necessary and sufficient for the purpose of stellar interior modelling. To explain the physical differences between the model grids we provide a description of the currently available modifications of ATLAS9 according to their treatment of convection. Our critical analysis of the dependence of the atmospheric structure and observable quantities on convection treatment, vertical resolution and metallicity reveals that spectroscopic and photometric observations are best represented when using an inefficient convection treatment. This conclusion holds whatever convection formulation investigated here is used, i.e. MLT(alpha = 0.5), CM and CGM are equivalent. We also find that changing the convection treatment can lead to a change in the effective temperature estimated from Stromgren color indices from 200 to 400 K.
Astronomy & Astrophysics, v.392, 619-636 (2002).
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[show abstract]
[hide abstract]
ABSTRACT: A library of 211 echelle spectra taken with ELODIE at the Observatoire de Haute-Provence is presented. It provides a set of spectroscopic standards covering the full range of gravities and metallicities in the effective temperature interval [4000 K, 6300 K]. The spectra are straightened, wavelength calibrated, cleaned of cosmic ray hits, bad pixels and telluric lines. They cover the spectral range [440 nm, 680 nm] with an instrumental resolution of 42000. For each star, basic data were compiled from the Hipparcos catalogue and the Hipparcos Input Catalogue. Radial velocities with a precision better than 100 $\mathrm{m~s}^{-1}$ are given. Atmospheric parameters ($T_\mathrm{eff}$, $\log g$, [Fe/H]) from the literature are discussed. Because of scattered determinations in the bibliography, even for the most well-known stars, these parameters were adjusted by an iterative process which takes account of common or different spectral features between the standards, using our homogeneous set of spectra. Revised values of effective temperature, gravity and metallicity are proposed. They are still consistent with the literature, and also lead to the self-consistency of the library, in the sense that similar spectra have similar atmospheric parameters. This adjustment was performed by using step by step a method based on the least square comparison of carefully prepared spectra, which was originally developed for the on-line estimation of the atmospheric parameters of faint field stars (companion paper in the main journal).
http://dx.doi.org/10.1051/aas:1998456.
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[show abstract]
[hide abstract]
ABSTRACT: We have computed a grid of synthetic spectra in the wavelength range $\lambda\lambda$ 4600–5600 Å using revised model atmospheres, for a range of atmospheric parameters and values of [ $\alpha\mbox{-elements/Fe}] = 0.0$ and +0.4. The Lick indices Fe5270, Fe5335, Mgb and Mg$_2$ are measured on the grid spectra for $FWHM = 2$ to $8.3$ Å. Relations between the indices Fe5270, Fe5335 and Mg$_2$ and the stellar parameters effective temperature $T_{\rm eff}, \log\; g$, [Fe/H] and [ $\alpha$/Fe] , valid in the range $4000 \leq T_{\rm eff} \leq 7000$ K, are presented. These fitting functions are given for $FWHM = 3.5$ and 8.3 Å. The indices were also measured for a list of 97 reference stars with well-known stellar parameters observed at ESO and OHP, and these are compared to the computed indices. Finally, a comparison of the indices measured on the observed spectra and those derived from the fitting functions based on synthetic spectra is presented.
http://dx.doi.org/10.1051/0004-6361:20030496.
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H. Bruntt,
I. F. Bikmaev,
C. Catala,
E. Solano,
M. Gillon,
P. Magain,
C. Van't Veer-Menneret,
C. Stütz,
W. W. Weiss,
D. Ballereau,
J. -C. Bouret,
S. Charpinet,
T. Hua, D Katz,
F. Lignières,
T. Lueftinger
[show abstract]
[hide abstract]
ABSTRACT: One of the goals of the ground-based support program for the corot and mons/rømer satellite missions is to characterize suitable target stars for the part of the missions dedicated to asteroseismology. We present the detailed abundance analysis of nine of the potential corot main targets using the semi-automatic software vwa. For two additional corot targets we could not perform the analysis due to the high rotational velocity of these stars. For five stars with low rotational velocity we have also performed abundance analysis by a classical equivalent width method in order to test the reliability of the vwa software. The agreement between the different methods is good. We find that it is necessary to measure abundances extracted from each line relative to the abundances found from a spectrum of the Sun in order to remove systematic errors. We have constrained the global atmospheric parameters $T_{\rm eff}$, $\log g$, and [Fe/H] to within $70{-}100$ K, $0.1{-}0.2$ dex, and 0.1 dex for five stars which are slow rotators ($v\sin i < 15 {\rm km\,s}^{-1}$). For most of the stars we find good agreement with the parameters found from line depth ratios, H $\alpha$ lines, Strömgren indices, previous spectroscopic studies, and also $\log g$ determined from the hipparcos parallaxes. For the fast rotators ($v\sin i > 60 {\rm km\,s}^{-1}$) it is not possible to constrain the atmospheric parameters.
http://dx.doi.org/10.1051/0004-6361:20040464.
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