========================================================================== J/A+A/519/A40 Nearby early-type gal. with ionized gas. IV. (Annibali+, 2010) The following files can be converted to FITS (extension .fit or fit.gz) table1.dat table2.dat table3.dat ========================================================================== Query from: http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=J/A+A/519/A40 ==========================================================================
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Beginning of ReadMe : J/A+A/519/A40 Spectroscopic study of 65 nearby galaxies (Annibali+, 2010) ================================================================================ Nearby early-type galaxies with ionized gas. IV. Origin and powering mechanism of the ionized gas. Annibali F., Bressan A., Rampazzo R., Zeilinger W.W., Vega O., Panuzzo P. <Astron. Astrophys. 519, A40 (2010)> =2010A&A...519A..40A ================================================================================ ADC_Keywords: Galaxies, nearby ; Galaxies, optical ; Galaxies, spectra Keywords: galaxies: elliptical and lenticular, cD - galaxies: ISM - galaxies: active - galaxies: abundances Abstract: With the aim of constraining the source of excitation and the origin of the ionized gas in early-type galaxies (ETGs), we analyzed intermediate resolution optical spectra of a sample of 65 ETGs mostly located in low density environments. Optical emission lines are detected in 89% of the sample. The incidence and strength of emission do not correlate either with the E/S0 classification, or with the fast/slow rotator classification. Comparing the nuclear r<r_e_/16 line emission with the classical [OIII]/Hb vs [NII]/Ha diagnostic diagram, the galaxy activity is so classified: 72% of the galaxies with emission are LINERs, 9% are Seyferts, 12% are Composite/Transition objects, and 7% are non-classified. Seyferts have young luminosity-weighted ages (<5Gyr), and appear, on average, significantly younger than LINERs and Composites. Excluding the Seyferts from our sample, we find that the spread in the ([OIII], Ha or [NII]) emission strength increases with the galaxy central velocity dispersion sigma_c_. The [NII]/Ha ratio decreases with increasing galacto-centric distance, indicating either a decrease of the nebular metallicity, or a progressive "softening" of the ionizing spectrum. The average oxygen abundance of the ionized gas is slightly less than solar, and a comparison with the results obtained in Paper III (Cat. J/A+A/463/455) from Lick indices reveals that it is 0.2dex lower than that of stars. Conclusions: the nuclear emission can be explained with photoionization by PAGB stars alone only in 22% of the LINERs/Composite sample. On the other hand, we can not exclude an important role of PAGB star photoionization at larger radii. For the major fraction of the sample, the nuclear emission is consistent with excitation from a low-accretion rate AGN, fast shocks (200-500km/s) in a relatively gas-poor environment (n<100cm^-3^), or coexistence of the two. The derived nebular metallicities suggest either an external origin of the gas, or an overestimate of the oxygen yields by SN models. Description: Fluxes and equivalent widths for the emission lines measured in the optical spectra of 65 nearby early-type galaxies. The emission lines are: [OII] lambda3727, [NeIII] lambda3869, Hbeta lambda4861, [OIII] lambda4959, [OIII] lambda5007, [OI] lambda6300, [NII] lambda6548, Halpha lambda6563, [NII] lambda6584, [SII] lambda6717, [SII] lambda6731. The emission lines were measured in 4 annuli of increasing galacto-centric distance: r<re/16 (where re is the effective radius), re/16<r<re/8, re/8<r<re/4, and re/4<r<re/2. The reddening E(B-V) was derived from the Hbeta and Halpha emission lines, assuming flux(Halpha)/flux(Hbeta)=3.1.