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J/A+A/396/449       Hα surface photometry in Virgo     (Gavazzi+, 2002)

Hα surface photometry of galaxies in the Virgo cluster. IV. The current star formation in nearby clusters of galaxies. Gavazzi G., Boselli A., Pedotti P., Gallazzi A., Carrasco L. <Astron. Astrophys. 396, 449 (2002)> =2002A&A...396..449G
ADC_Keywords: Clusters, galaxy ; Galaxies, photometry ; Photometry, surface Keywords: galaxies: photometry - galaxies: clusters: individual: Virgo Abstract: Hα+[NII] imaging observations of 369 late-type (spiral) galaxies in the Virgo cluster and in the Coma/A1367 supercluster are analyzed, covering 3 rich nearby clusters (A1367, Coma and Virgo) and nearly isolated galaxies in the Great-Wall. They constitute an optically selected sample (mp<16.0) observed with ∼60% completeness. These observations provide us with the current (T<107yrs) star formation properties of galaxies that we study as a function of the clustercentric projected distances (Theta). The expected decrease of the star formation rate (SFR), as traced by the Hα equivalent width, with decreasing Theta is found only when galaxies brighter than Mp∼19.5 are considered. Fainter objects show no or reverse trends. We also include in our analysis Near Infrared data, providing information on the old (T>109yrs) stars. Put together, the young and the old stellar indicators give the ratio of currently formed stars over the stars formed in the past, or "birthrate" parameter b. For the considered galaxies we also determine the "global gas content" combining HI with CO observations. We define the "gas deficiency'' parameter as the logarithmic difference between the gas content of isolated galaxies of a given Hubble type and the measured gas content. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table4.dat 56 369 Parameters of the analyzed galaxies.
See also: VII/190 : Zwicky Galaxy Catalog (Zwicky+ 1968) J/AJ/90/1681 : The Virgo Cluster Catalog (VCC) (Binggeli+, 1985) Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1 A1 --- Cluster [VC] V: Virgo, C: Coma/A1367 supercluster 3- 10 A8 --- Gal Galaxy designation (1) 12- 16 A5 --- Memb The membership to a cluster or supercluster (2) 18- 20 A3 --- MType Morphological type as given in the VCC or in Gavazzi & Boselli (1996ApL&C..35....1G) 22- 26 F5.2 deg Theta Projected angular separation from the nearest cluster center 28- 32 F5.2 mag Hmag Asymptotic H band magnitude, as described in Gavazzi et al. (2000, Cat. J/A+A/361/863) 34- 36 I3 Mpc Dist Distance (3) 38- 42 F5.2 --- Defgas ? Gas deficiency parameter (4) 44- 46 I3 0.1nm EW Halpha+[NII] equivalent width 48- 53 F6.2 [mW/m2] Log(FHa) Log of the Halpha flux deblended from the [NII] contribution and corrected for internal extinction as in Boselli et al. (2001AJ....121..753B). 55- 56 A2 --- Ref Reference to the Halpha data (5)
Note (1): Galaxy designations: VCC: Virgo Cluster Catalogue, Binggeli et al., 1985, Cat. J/AJ/90/1681, for Virgo galaxies Z: CGCG catalogue Zwicky et al., 1961-68, see Cat. VII/190, for Coma supercluster galaxies. Note (2): Defined as in Gavazzi et al. (1999MNRAS.304..595G) for Virgo and Gavazzi et al. (1999A&AS..136..227G) for the Coma/A1367 supercluster. A1367 : Member of A1367 cluster Coma : Member of Coma cluster Grp : Member of a group Iso : Isolated Prs : Pairs VA : Member of Virgo A VB : Member of Virgo B VE : Member of Virgo E VM : Member of Virgo M VN : Member of Virgo N VS : Member of Virgo S VW : Member of Virgo W VZ : Member of Virgo Z Note (3): We assume 17 Mpc for Virgo A, N, S, E, 23 Mpc for Virgo B and 32 Mpc for Virgo W, M, as given in Gavazzi et al. (1999MNRAS.304..595G), 96 Mpc for Coma, 91 Mpc for A1367. For galaxies not belonging to the clusters, the distance is determined from the redshift using H0=75km/s/Mpc. Note (4): Logarithmic difference between the gas content of isolated galaxies of a given Hubble type and the measured gas content. Note (5): References: 1: Kennicutt & Kent, 1983AJ.....88.1094K 2: Kennicutt et al., 1994ApJ...435...22K 3: Gavazzi et al., 1991AJ....101.1207G 4: Romanishin, 1990AJ....100..373R 5: Gavazzi et al., 1998AJ....115.1745G 6: Almoznino & Brosch, 1998MNRAS.298..920A 7: Boselli & Gavazzi, 2002A&A...386..124B, Paper II 8: Moss et al., 1998MNRAS.300..205M 9: Heller et al., 1999MNRAS.304....8H 10: Usui et al., 1998AJ....116.2166U 11: Gavazzi et al., 2002A&A...386..114G, Paper I 12: Boselli et al., 2002A&A...386..134B, Paper III 13: Koopmann et al., 2001ApJS..135..125K 14: Iglesias et al., 2002, Cat. J/A+A/384/383 TW: This work.
History: From electronic version of the journal References: Gavazzi et al., Paper I 2002A&A...386..114G Boselli & Gavazzi, Paper II 2002A&A...386..124B Boselli et al., Paper III 2002A&A...386..134B
(End) James Marcout, Patricia Bauer [CDS] 20-Jan-2003
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