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Total magnitude, radius, colour indices, colour gradients and photometric type of galaxies
We present a catalogue of aperture photometry of galaxies, in UBVRI,assembled from three different origins: (i) an update of the catalogueof Buta et al. (1995) (ii) published photometric profiles and (iii)aperture photometry performed on CCD images. We explored different setsof growth curves to fit these data: (i) The Sersic law, (ii) The net ofgrowth curves used for the preparation of the RC3 and (iii) A linearinterpolation between the de Vaucouleurs (r(1/4) ) and exponential laws.Finally we adopted the latter solution. Fitting these growth curves, wederive (1) the total magnitude, (2) the effective radius, (3) the colourindices and (4) gradients and (5) the photometric type of 5169 galaxies.The photometric type is defined to statistically match the revisedmorphologic type and parametrizes the shape of the growth curve. It iscoded from -9, for very concentrated galaxies, to +10, for diffusegalaxies. Based in part on observations collected at the Haute-ProvenceObservatory.
| The molecular gas content of spiral galaxies in compact groups.
We present ^12^CO(J=1-0) line observations of 15 late-type opticallyselected galaxies in compact groups. In order to study the effects ofenvironment on the molecular content of compact group galaxies we usethe CO(1-0) emission to estimate an indicative molecular hydrogencontent of the target galaxies adopting a standard conversion factorX=N(H_2_)/I(CO). We compare the frequency distribution of the normalizedhybrid molecular gas surface density to the one obtained for anoptically selected reference sample of isolated galaxies. Despite theirhigh-density environment, compact group galaxies have, on average,similar CO emission compared to isolated galaxies of same sizes andluminosities. However there are some compact group galaxies withperturbed morphologies and high far-infrared fluxes which have anenhanced CO emissivity.
| The stellar-free emission component in galactic nuclei - At low-levels, evidence for shock ionization
The emission-line component in a sample of 92 galaxies was isolatedusing stellar absorption templates built from emission-free star clusterspectra and taking into account all sources of reddening extrinsic tothe line emitting regions, and the emission line properties werestatistically analyzed. Three characteristic average spectra were built,including those corresponding to nuclear H II regions, objectsidentified as LINERs, and extreme low-level emission galaxies with W(em)of not greater than 2 A. For the latter, line measurements were pusheddown to very low level. The measurements of the ratio between forbiddenS II line and forbidden S III line indicate that, in the extremelow-level emission galaxies, the shock ionization is the mechanism atwork.
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