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We present the first release of XSL, the X-Shooter Spectral Library. This release contains 237 stars spanning the wavelengths 3000--10200 \AA\ observed at a resolving power $R \equiv \lambda / \Delta\lambda \sim 10000$. The spectra were obtained at ESO's 8-m Very Large Telescope (VLT). The sample contains O -- M, long-period variable (LPV), C and S stars. The spectra are flux-calibrated and telluric-corrected. We describe a new technique for the telluric correction. The wavelength coverage, spectral resolution and spectral type of this library make it well suited to stellar population synthesis of galaxies and clusters, kinematical investigation of stellar systems and studying the physics of cool stars., Comment: 41 pages, 38 figures, 5 tables. Accepted for publication in A&A. Webpage: http://xsl.u-strasbg.fr/

Dwarf galaxies are generally faint. To derive their age and metallicity distributions, it is critical to optimize the use of any collected photon. Koleva et al., using full spectrum fitting, have found strong population gradients in some dwarf elliptical galaxies. Here, we show that the population profiles derived with this method are consistent and more precise than those obtained with spectrophotometric indices. This allows studying fainter objects in less telescope time., Comment: 2 pages, 1 figure, to appear in the proceedings of the CRAL conference, Lyon, June 2010, "A Universe of Dwarf Galaxies", eds. M. Koleva, Ph. Prugniel and I. Vauglin; EDP Sciences in the European Astronomical Society

We compare six popularly used evolutionary population synthesis (EPS) models (BC03, CB07, Ma05, GALEV, GRASIL, Vazdekis/Miles) through fitting the full optical spectra of six representative types of galaxies (star-forming and composite galaxies, Seyfert 2s, LINERs, E+A and early-type galaxies), which are taken from the Sloan Digital Sky Survey (SDSS). Throughout our paper, we use the simple stellar populations (SSPs) from each EPS model and the software STARLIGHT to do our fits. Our main results are: Using different EPS models the resulted numerical values of contributed light fractions change obviously, even though the dominant populations are consistent. The stellar population synthesis does depend on the selection of age and metallicity, while it does not depend on the stellar evolution track much. The importance of young populations decreases from star-forming, composite, Seyfert 2, LINER to early-type galaxies, and E+A galaxies lie between composite galaxies and Seyfert 2s in most cases. We conclude that different EPS models do derive different stellar populations, so that it is not reasonable to directly compare stellar populations estimated from different EPS models. To get reliable results, we should use the same EPS model for the compared samples., Comment: 13 pages, 4 figures, accepted for publication in A&A

NGC404 is a nearly face-on nearby low-luminosity lenticular galaxy. Probing its characteristics provides a wealth of information on the details of possible evolution processes of dS0 galaxies which may not be possible in other, more distant objects. In order to study its kinematics and star formation history, we obtained long slit spectroscopy at the OHP 1m93 telescope along the major and minor axes of NGC404. The spectra have a resolution R = 3600 covering a wavelength range from 4600 to 5500 A. The data are fitted against the Pegase.HR stellar population models to derive simultaneously the internal stellar kinematics, ages and metallicities. Firstly, the global properties of the galaxy are analyzed by fitting a single model and to the data and looking at the kinematic variations and SSP equivalent age and metallicities as a function of radius. Afterwards, the stellar populations are decomposed into 4 components that are individually analyzed. NGC404 clearly shows two radial velocity inversions along its major axis. The kinematically decoupled core rotates in the same direction as the neutral hydrogen shell that surrounds the galaxy. We resolved the star formation history in the core of the galaxy ino 4 events: A very young (< 150 Myr, and [Fe/H] = 0.4) component with constant on-going star formation, a second young (430 Myr) component with [Fe/H] = 0.1, an intermediate population (1.7 Gyr) which has [Fe/H] = -0.05 and, finally, an old (12 Gyr) component with [Fe/H] = -1.26. The two young components fade very quickly with radius, leaving only the intermediate and old population at a radius of 25" (370 pc) from the centre. We conclude that NGC404 had a spiral morphology about 1 Gyr ago and that one or many merger events has triggered a morphological transition., Comment: 8 pages, 8 figures, accepted for publication in A&A

The formation and evolution of galaxies is imprinted on their stellar population radial gradients. Two recent articles present conflicting results concerning the mass dependence of the metallicity gradients for early-type dwarf galaxies. On one side, Spolaor et al. show a tight positive correlation between the total metallicity, Z/H and the mass. On the other side, in a distinct sample, we do not find any trend involving Fe/H (Koleva et al.). In order to investigate the origin of the discrepancy, we examine various factors that may affect the determination of the gradients: namely the sky subtraction and the signal-to-noise ratio. We conclude that our detection of gradients are well above the possible analysis biases. Then, we measured the Mg/Fe relative abundance profile and found moderate gradients. The derived Z/H gradients scatter around -0.4 dex/r_e. The two samples contain the same types of objects and the reason of the disagreement is still not understood. Based on observations made with ESO telescopes at La Silla Paranal observatory under program ID076.B-0196., Comment: 6 pages, 4 figures, Talk for "Matter Cycles of Galaxies in Clusters", JENAM 2008, Vienna, to be published in Astronomische Nachrichten; (1) IAC, Spain (2) Observatoire de Lyon, France (3) Ghent University, Belgium (4) University of Vienna, Austria

Fitting whole spectra at intermediate spectral resolution (R = 1000 -- 3000), to derive physical properties of stellar populations, appears as an optimized alternative to methods based on spectrophotometric indices: it uses all the redundant information contained in the signal. This paper addresses the validation of the method and it investigates the quality of the population models together with the reliability of the fitting procedures. We are using two algorithms: STECKMAP, a non-parametric regularized program and NBURSTS a parametric non-linear minimization. We compare three spectral synthesis models for single stellar populations: Pegase-HR, Galaxev (BC03) and Vazdekis/Miles, and we analyse spectra of Galactic clusters whose populations are known from studies of color-magnitude diagrams (CMD) and spectroscopy of individual stars. We find that: (1) The quality of the models critically depends on the stellar library they use. Pegase-HR and Vazdekis/Miles are consistent, while the comparison between Pegase-HR and BC03 shows some systematics reflecting the limitations of the stellar library (STELIB) used to generate the latter models; (2) The two fitting programs are consistent; (3) For globular clusters and M67 spectra, the method restitutes metallicities in agreement with spectroscopy of stars within 0.14 dex; (4) The spectroscopic ages are very sensitive to the presence of a blue horizontal branch (BHB) or of blue stragglers. A BHB morphology results in a young SSP-equivalent age. Fitting a free amount of blue stars in addition to the SSP model to mimic the BHB improves and stabilizes the fit and restores ages in agreement with CMDs studies. This method is potentially able to disentangle age or BHB effects in extragalactic clusters., Comment: accepted in MNRAS; Full version available at http://www-obs.univ-lyon1.fr/labo/perso/prugniel/mina/koleva.pdf

We built modelled spectra of stellar population at high resolution and with variable alpha-elements enhancements. Analysing spectra of Galactic globular clusters we show that it is possible to derive reliably and efficiently [Mg/Fe] using spectra integrated along the line-of-sight. These detailed measurements open perspectives for investigating the enrichment process on galaxies and star clusters., Comment: 2 pages, 2 figures, to appear in Pathways through an eclectic Universe, J. H. Knapen, T. J. Mahoney, and A. Vazdekis (Eds.), ASP Conf. Ser., 2007

We present ELODIE.3.1, an updated release of the library published in Prugniel & Soubiran (2001, 2004). The library includes 1962 spectra of 1388 stars obtained with the ELODIE spectrograph at the Observatoire de Haute-Provence 193cm telescope in the wavelength range 390 to 680 nm. It provides a wide coverage of atmospheric parameters : T_eff from 3100 K to 50000 K, log g from -0.25 to 4.9 and [Fe/H] from -3 to +1. The library is given at two resolutions: R~42000, with the flux normalized to the pseudo-continuum, FWHM=0.55\AA (R~10000) calibrated in physical flux (reduced above earth atmosphere) with a broad-band photometric precision of 2.5% and narrow-band precision of 0.5%. In this new release the data-reduction (flux calibration, reconnection of the echelle orders) has been improved, and in particular the blue region, between 390 and 400 nm has been added. The FITS files for each spectra, and the measured atmospheric parameters are publicly available. See the ELODIE.3.1 page for more details: http://www.obs.u-bordeaux1.fr/m2a/soubiran/elodie_library.html, Comment: v2 removed unused figures

We acquired radial velocities of a significant number of globular clusters (GCs) on wide fields between galaxies in the nearby Fornax cluster of galaxies, in order to derive their velocity dispersion radial profile and to probe the dynamics of the cluster. We used FLAMES on the VLT to obtain accurate velocities for 149 GCs, within a ~500x150 kpc strip centered on NGC 1399, the Fornax central galaxy. These objects are at the very bright tail (M_V < -9.5) of the GC luminosity function, overlapping the so-called ``ultra-compact dwarfs'' magnitude range. Eight of the brightest FLAMES-confirmed members indeed show hints of resolution in the subarcsecond pre-imaging data we used for selecting the ~500 targets for FLAMES spectroscopy. Ignoring the GCs around galaxies by applying 3d_25 diameter masks, we find 61 GCs of 20.0 < V < 22.2 lying in the intra-cluster (IC) medium. The velocity dispersion of the population of ICGCs is 200 km/s at ~150 kpc from the central NGC 1399 and rises to nearly 400 km/s at 200 kpc, a value which compares with the velocity dispersion of the population of dwarf galaxies, thought to be infalling from the surroundings of the cluster., Comment: To be published in A&A Letters. 4 pages, 3 figures, 3 tables

The MIGALE project (http://www.sai.msu.su/migale) provides databases and data analysis tools to study the evolution of galaxies from z=1 to z=0. It develops and maintain a general database, HyperLeda, to give a homogenized parameterization for 3 million objects, and several archives or specialized databases. It also develops tools to analyse on-the-fly data extracted from the database or obtained through the Virtual Observatory (Virtual Instruments). The package made for this project, Pleinpot, is distributed as open source., Comment: SF2A-2004 conference, 4 pages, 1 figure

We present ELODIE.3, an updated release of the ELODIE library originally published in Prugniel & Soubiran (2001). It is part of the spectrophotometric resources available in the HyperLeda database where the spectra can be visualized or downloaded in FITS format. The ELODIE library includes 1962 spectra of 1388 stars obtained with the ELODIE spectrograph at the Observatoire de Haute-Provence 193cm telescope in the wavelength range 400 to 680 nm. It provides a large coverage of atmospheric parameters : Teff from 3000 K to 60000 K, log g from -0.3 to 5.9 and [Fe/H] from -3.2 to +1.4. The library is given at two resolutions: R=42000, with the flux normalized to the pseudo-continuum, R=10000 calibrated in physical flux (reduced above earth atmosphere) with a broad-band photometric precision of 2.5% and narrow-band precision of 0.5%. A grid of interpolated spectra is also given, which has been used for synthesis of stellar population with PEGASE-HR (Le Borgne et al. 2004). Compared to the previous version we have doubled the size of the library, corrected some identification errors, improved the external stellar parameters and the reduction procedure. A detailed description is available at the ELODIE.3 website : http://www.obs.u-bordeaux1.fr/m2a/soubiran/elodie_library.html, Comment: 3 pages, website address updated

The ELODIE archive contains the complete collection of high-resolution echelle spectra accumulated over the last decade using the ELODIE spectrograph at the Observatoire de Haute-Provence 1.93-m telescope. This article presents the different data products and the facilities available on the web to re-process these data on-the-fly. Users can retrieve the data in FITS format from http://atlas.obs-hp.fr/elodie and apply to them different functions: wavelength resampling and flux calibration in particular., Comment: 8 pages, 3 figures and 1 table

The Hypercat Database is developed at Observatoire de Lyon and is distributed on the WEB through different mirrors in Europe. The goal of Hypercat is to gather data necessary for studying the evolution of galaxies (dynamics and stellar contains) and particularly for providing a z=0 reference for these studies., Comment: 2 pages, no figure, to appear in "Galaxy Dynamics: from the Early Universe to the Present", ASP Conf Series, ed. F. Combes, G. Mamon, V. Charmandaris. Now with the URL of Hypercat

We have studied the population-density relation in very sparse environments, from poor clusters to isolated galaxies, and we find that early-type galaxies with a young stellar population are preferably found in the lowest density environments. We show a marginal indication that this effect is due to an enhancement of the stellar formation independent of the morphological segregation, but we failed to find any effect from the internal dynamics., Comment: 2 pages, 2 figures, to appear in "Galaxy Dynamics: from the Early Universe to the Present", ASP Conf Series, ed. F. Combes, G. Mamon, V. Charmandaris Unmatched "

In order to study the influence of the environment on the stellar population of early-type galaxies we have analyzed the relations between the density of the environment (lrho) and the residuals to the Mg2-sigma relation, R_a, and between lrho and the residuals to the Fundamental Plane, R_f. Our sample of galaxies covers the range of densities, between field galaxies and poor clusters. We confirm the existence of a slight environmental bias on the mean stellar population and we show that this effect is due to a small fraction of galaxie s containing a younger stellar sub-population while the majority of galaxies, in any environment, are equally old. The galaxies which are likely to contain a young stellar sub-population (negative R_a and R_f) are preferentially found in the less dense environment. This segregation of the stellar population may reflect the morphology-density relation or may result from a higher rate of recent star formation activity in sparse environments. Using the rotational support to assess the presence of a disk and to parameterize the morphology, we subtracted the contribution of the morphological segregation to population segregation. It is not yet possible to rule out that the morphology-density relation is at the origin of the population-density relation., Comment: 5 pages, 2 figures. Accepted for A&A (letters to the editors)