Formation and evolution of dwarf early-type galaxies in the Virgo cluster I. Internal kinematics

Astronomy and Astrophysics (Impact Factor: 5.08). 11/2010; DOI: 10.1051/0004-6361/201015344
Source: arXiv

ABSTRACT We present new medium resolution kinematic data for a sample of 21 dwarf early-type galaxies (dEs) mainly in the Virgo cluster, obtained with the WHT and INT telescopes at the Roque de los Muchachos Observatory (La Palma, Spain). These data are used to study the origin of the dwarf elliptical galaxy population inhabiting clusters. We confirm that dEs are not dark matter dominated galaxies, at least up to the half-light radius. We also find that the observed galaxies in the outer parts of the cluster are mostly rotationally supported systems with disky morphological shapes. Rotationally supported dEs have rotation curves similar to those of star forming galaxies of similar luminosity and follow the Tully-Fisher relation. This is expected if dE galaxies are the descendant of low luminosity star forming systems which recently entered the cluster environment and lost their gas due to a ram pressure stripping event, quenching their star formation activity and transforming into quiescent systems, but conserving their angular momentum. Comment: 24 pages, 15 figures and 7 tables. Replaced to match the journal version

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    ABSTRACT: The new World Wide Web site "GOLDMine" (Galaxy On Line Database Milano Network) ( contains a multiwavelength data-base of an optically selected sample of 3267 galaxies in the Virgo cluster and in the Coma Supercluster. It is designed for professional astronomers who wish to find data and images for these galaxies. Data, gathered in 15 years of observational campaigns by the authors or taken from the literature include general parameters (catalogue names, celestial coordinates, morphological type, recessional velocity etc.); multiwavelength continuum photometry (total UV, U, B, V, J, H, K, FIR and radio magnitudes/flux densities); line photometry (HI, H_2, H_alpha); dynamical parameters (rotational velocity from the HI and H_alpha lines, velocity dispersion) and structural parameters (light concentration index, effective radius and brightness, asymptotic magnitude) in the optical (B and V) and Near Infrared (H or K) bands. Images include finding charts, optical (B and V), H_alpha, Near Infrared (H and/or K) and true color RGB frames (when available). Radial light profiles obtained from the B, V, H or K band images are also available. Integrated optical spectra along with broad Spectral Energy Distributions (SED) from the UV to the radio domain are given. All images can be obtained in JPG format, but the original (reduced) FITS images can be downloaded as well. The database will be updated regularly and will be extended to other local clusters and superclusters. Astronomers who wish to have their images included in GOLDMine are strongly encouraged to send us their material.
    Astronomy and Astrophysics 01/2003; · 5.08 Impact Factor
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    ABSTRACT: (shortened) We have obtained blue integrated spectra of 175 nearby early-type galaxies, covering a wide range in galaxy velocity dispersion, and emphasizing those with sigma < 100 km/s. Galaxies have been observed both in the Virgo cluster and in lower-density environments. The main goals are the evaluation of higher order Balmer lines as age indicators, and differences in stellar populations as a function of mass, environment and morphology. In this first paper our emphasis is on presenting the evolutionary population synthesis models. Lower-sigma galaxies exhibit a substantially greater intrinsic scatter, in a variety of line strength indicators, than do higher-sigma galaxies, with the large intrinsic scatter setting in below a sigma of 100 km/s. Modeling of the observed spectral indices indicates that the strong Balmer lines found primarily among the low-sigma galaxies are caused by young age, rather than by low metallicity. Thus we find a trend between the population age and the velocity dispersion, such that low sigma galaxies have younger luminosity-weighted mean ages. We have repeated this analysis using several different Balmer lines, and find consistent results from one spectral indicator to another. Comment: To appear in AJ. Full version of Table 3 is available as a separate file
    The Astronomical Journal 03/2003; · 4.97 Impact Factor
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    ABSTRACT: In this Paper we investigate the kinematical properties of early-type dwarfs by significantly enlarging the scarce observational sample so far available. We present rotation curves and mean velocity dispersions for four bright dwarf ellipticals and two dwarf lenticular galaxies in the Virgo cluster. Most of these galaxies exhibit conspicuous rotation curves. In particular, five out of the six new galaxies are found to be close to the predictions for oblate spheroids flattened by rotation. Therefore, and contrary to the previous observational hints, the present data suggest that an important fraction of dwarf early-type galaxies may be rotationally supported. Comment: 5 pages, 4 figures, MNRAS accepted
    Monthly Notices of the Royal Astronomical Society 04/2002; · 5.52 Impact Factor

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