1,721,007 research outputs found
'Global mapping' B-band photometry of a complete sample of Fornax and Virgo early-type galaxies
No full textWe present the B-band surface photometry of 19 early-type galaxies of the Virgo cluster, and of 28 galaxies of the same morphological type belonging to the Fornax clusters, obtained through the `global mapping' technique which couples CCD and photographic plates. Taking into account 33 galaxies already studied by Caon et al. (1990) with the same methodology, the Virgo sample of early-type galaxies is now 80% complete down to B_T_=14. The Fornax sample is 95% complete down to B_T_=15. The geometric and photometric properties of the total sample of 80 galaxies are derived measuring accurate light profiles, ellipticities, position angles and Fourier coefficients of the isophotes. The main sources of errors of the `global mapping' procedure are reviewed and the effects of seeing discussed. Global galaxian parameters such as total luminosity, effective radius, and effective surface brightness, are computed for the whole sample in a homogeneous way. Our goal is to create an unbiased set of data to be used for investigating the process of galaxy formation and evolution
On the shape of the light profiles of Early Type galaxies
No full textWe have obtained the best fit to the light profiles of a luminosity- limited sample of elliptical and S0 galaxies with a power law r^1/n^, letting the exponent remain free rather than keeping it fixed at 1/n = 1/4 as in the well-known de Vaucouleurs formula. The introduction of a free parameter in the fitting formula (ranging from n = 0.5 for (r_e_) = 0.3 kpc to n = 16 for (r_e_) = 25 kpc) is justified by the existence of a good correlation between n and the global galaxian parameters, such as total luminosity and scale-radius. This result seems to be in line with the segregation of properties between the `ordinary' and `bright' families of early-type galaxies, and has consequences for the claimed independence of the shape of galaxy profiles with respect to the Fundamental Plane parameters
Families of galaxies in the mue-Re plane
No full textOn the basis of a sample of Virgo cluster galaxies in a larger set of heterogeneous literature data, it is shown that ellipticals, early-type dwarfs, and bulges of S0s and of spirals form two distinct families in the plane of the effective parameters, R(e) and mu(e). The 'ordinary' family is composed of all galaxies fainter than MB of about -19.3. Their effective parameters range over a wide interval for the same total luminosity: R(e) varies by at least 0.7 dex and mu(e) by 3.5 mag. The 'bright' family is composed of the brightest cluster members and the host galaxies of QSOs. Their effective radii extend up to about 300 kpc, and are directly related to the effective surface brightness: mu(e) of about 3 log R(e)+constant. It is suggested that the objects belonging to this family have undergone merging phenomena
B-band photometry in Fornax and Virgo (Caon+ 1994)
No full textVizieR On-line Data Catalog: J/A+AS/106/19
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