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J/ApJ/517/650   Surface photometry of dwarf galaxies in Virgo  (Ryden+, 1999)
Detailed surface photometry of dwarf elliptical and dwarf S0 galaxies
in the Virgo cluster
    Ryden B.S., Terndrup D.M., Pogge R.W., Lauer T.R.
   <Astrophys. J. 517, 650 (1999)>
   =1999ApJ...517..650R
ADC_Keywords: Clusters, galaxy ; Photometry, surface

Keywords: galaxies: clusters: individual (Virgo) - galaxies:
          elliptical and lenticular, cDgalaxies: photometry - galaxies:
          structure

Abstract:
    We analyze new V-band images of 14 dwarf S0 galaxies and 10 dwarf
    elliptical galaxies in the Virgo Cluster, in combination with R-band
    images of 70 dwarf elliptical galaxies from an earlier paper. We
    compute the intensity-weighted mean ellipticity, the mean deviations
    from elliptical isophotes, and a newly defined parameter to measure
    isophotal twists. We also fit each major-axis profile to a power law
    Σ(a) ∝ exp[-(a/as)n], where n is allowed to vary.
    Consistent with other studies of the Virgo dwarf ellipticals, we find
    that the profile shapes for the entire sample is strongly peaked near
    n=1 (exponential profiles) and that no galaxies have n=1/4 (de
    Vaucouleurs profile). The faintest galaxies all have nearly
    exponential profiles, while the brighter ones on average have n<1. The
    correlation between ellipticity and the boxy/disky parameter is
    similar to that of large elliptical galaxies, suggesting that dwarfs
    may also be divided into two groups with differing internal dynamics.
    The Virgo dEs also show a greater degree of isophotal twisting than
    more luminous elliptical galaxies.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table2.dat       103       93   Results of the dwarf galaxy surface photometry


See also:
   J/A+AS/139/491 : BVI photometry of nearby galaxies (Makarova+, 1999)
   J/MNRAS/279/595 : Blue compact dwarf galaxies in Virgo (Drinkwater+ 1996)
   J/A+AS/127/367 : Virgo Photometry Catalogue (VPC) (Young+ 1998)


Byte-by-byte Description of file: table2.dat

   Bytes Format Units   Label     Explanations

   1-  4  I4    ---     VCC       Galaxy number from VCC (1)
   9- 12  A4    ---     Class     Galaxy classification from VCC (1)
      14  A1    ---     f_Class   [N] Indicates the presence of a nucleus
  17- 20  I4    yr      Obs.Y     Year observation was obtained in
  23- 26  F4.1  arcsec  Rad       ? Outer fiducial radius where the intensity
                                   is < 180 counts
  33- 36  F4.2  ---     Ellip     Mean ellipticity
      39  A1    ---     f_Ellip   [a] Indicates Ellip estimated in Ryden+
                                      (1994ApJ...425...43R)
  45- 48  F4.2  ---     E(Rad)    ? Ellipticity at Rad
  53- 61  E9.2  ---     Box       ? Intensity weighted boxiness coefficient
  66- 74  E9.2  ---     e_Box     ? Uncertainty in Box
  77- 85  E9.2  ---     Twist     ? Dimensionless twisting statistic
  91- 94  F4.2  ---     Index     ? Power law exponent of the surface
                                   brightness (2)
 100-103  F4.2  ---     e_Index   ? Uncertainty in Index

Note (1):
    VCC = Virgo Cluster Catalog. Binggeli, B., Sandage, A., & Tammann,
          G. A. 1985, AJ, 90, 1681 (1985AJ.....90.1681B)
Note (2): surface brightness ∝ exp[-(semi-major axis/scale radius)n].
    An Index value of 1 and 1/4 are exponential and de Vaucouleurs (1948)
    profiles respectively.


History:
    From ApJ electronic edition

References:
    de Vaucouleurs, G. 1948, Ann. d'Astrophys., 11, 247
(End)                                          Greg Schwarz [AAS]    08-Mar-2000