Volume 372, Number 1, June II 2001
|Page(s)||29 - 49|
|Section||Cosmology (including clusters of galaxies)|
|Published online||15 June 2001|
m (H -band) surface photometry of galaxies*
VII. Dwarf galaxies in the Virgo Cluster
Università degli Studi di Milano-Bicocca, P.zza dell'Ateneo Nuovo 1, 20126 Milano, Italy
2 Institut d'Astrophysique de Marseille, Traverse du Siphon, 13376 Marseille Cedex 12, France
3 Istituto di Fisica Cosmica "G. Occhialini", CNR, via Bassini 15, 20133 Milano, Italy
Corresponding author: G. Gavazzi, Giuseppe.Gavazzi@mib.infn.it
Accepted: 21 March 2001
We present near-infrared H-band (1.65 μm ) observations and surface brightness profile decompositions for 75 faint () galaxies, primarily taken among dwarf Ellipticals members of the Virgo cluster, with some Centaurus Cluster members, a BCD and two peculiar galaxies taken as fillers. We model their surface brightness profiles with a de Vaucouleurs (D), exponential (E), mixed (bulge+disk or M) or truncated (T) law, and we derive for each galaxy the H band effective surface brightness () and effective radius (re), the asymptotic total magnitude HT and the light concentration index C31, defined as the ratio between the radii that enclose 75% and 25% of the total light HT. For a subsample we compare the NIR surface photometry with similar data taken in the B and V bands, and we give the and color profiles. Combining the present data with those previously obtained by our group (1157 objects) we analyze the NIR properties of a nearly complete sample, representative of galaxies of all morphological types, spanning 4 decades in luminosity. We confirm our earlier claim that the presence of cusps and extended haloes in the light profiles () is a strong, non-linear function of the total luminosity. We also find that: i) among dE and dS0 galaxies D profiles are absent; 50% of the decompositions are of type M, the remaining being of type E or T. ii) Less than 50% of the giant elliptical galaxies have pure D profiles, the majority being represented by M profiles. iii) Most giant galaxies (from elliptical to Sb) have M profiles. iv) Most of late type spirals (Scd to BCD) have either E or T profiles. v) The type of decomposition is a strong function of the total H band luminosity, independent of the Hubble classification: the fraction of type E decompositions decreases with increasing luminosity, while those of type M increase with luminosity. Pure D profiles are absent in the low luminosity range and become dominant above 1011 , while T profiles are present only among low luminosity galaxies. vi) We find that dE-peculiar galaxies have structural parameters indistinguishable from those of late-type dwarfs, thus they might represent the missing link between dEs and dIs.
Key words: galaxies: fundamental parameters / galaxies: photometry / infrared: galaxies
Based on observations taken with the ESO/NTT (ESO program 64.N-0288), with the Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Centro Galileo Galilei of the CNAA at the Spanish Observatorio del Roque de los Muchachos of the IAC, with the San Pedro Martir 2.1 m telescope of the Observatorio Astronomico Nacional (OAN, Mexico), and with the OHP 1.2 m telescope, operated by the French CNRS.
© ESO, 2001
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