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J/AJ/109/874 Kinematics of MKW and AWM Poor Clusters (Beers+ 1995)
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Kinematics and Dynamics of the MKW/AWM Poor Clusters
Beers T.C., Kriessler J.R., Bird C.M., Huchra J.P.
<Astron. J. 109, 874 (1995)>
=1995AJ....109..874B
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ADC_Keywords: Clusters, galaxy ; Redshifts
Abstract:
We report 472 new redshifts for 416 galaxies in the regions of the 23
poor clusters of galaxies originally identified by Morgan, Kayser, and
White, and Albert, White and Morgan. Eighteen of the poor clusters now
have 10 or more available redshifts within 1.5h^-1 Mpc of the central
galaxy; 11 clusters have at least 20 available redshifts. Based on the
21 clusters for which we have sufficient velocity information, the
median velocity scale is 336 km/s, a factor of 2 smaller than found
for rich clusters. Several of the poor clusters exhibit complex
velocity distributions due to the presence of nearby clumps of
galaxies. We check on the velocity of the dominant galaxy in each poor
cluster relative to the remaining cluster members. Significantly high
relative velocities of the dominant galaxy are found in only 4 of 21
poor clusters, 3 of which we suspect are due to contamination of the
parent velocity distribution. Several statistical tests indicate that
the D/cD galaxies are at the kinematic centers of the parent poor
cluster velocity distributions. Mass-to-light ratios for 13 of the 15
poor clusters for which we have the required data are in the range
50 <= M/L_B(0) <= 200 Msun/Lsun. The complex nature of the regions
surrounding many of the poor clusters suggests that these groupings
may represent an early epoch of cluster formation. For example, the
poor clusters MKW7 and MKW8 are shown to be gravitationally bound and
likely to merge to form a richer cluster within the next several Gyrs.
Eight of the nine other poor clusters for which simple two-body
dynamical models can be carried out are consistent with being bound to
other clumps in their vicinity. Additional complex systems with more
than two gravitationally bound clumps are observed among the poor
clusters.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 71 1097 *Velocities for galaxies in poor clusters
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Note on table2.dat:
Table 2 summarizes the best available velocities for galaxies located
within three degrees of the bright central galaxy in each MKW/AWM
poor cluster. In assembling this data set, new measurements were
supplemented with the extensive redshift catalog of Huchra et al.
[1992BICDS..41...31H]. In general, the poor clusters have velocity
dispersions that are less than 600 km/s (larger apparent dispersions
are shown to be due to contamination of the poor cluster velocity
distribution). Thus, for the purpose of the detailed kinematical
analysis, a subset of galaxies are identified in the region of each
poor cluster which have velocities within +/-2000 km/s of the D/cD
galaxy. Galaxies in each poor cluster that have velocities in this
range and that are located within 1.5h^-1* Mpc of the D/cD galaxy
(at its redshift distance) are assigned to subsample A. Those
galaxies within the velocity window that lie outside the
1.5h^-1^ Mpc radial distance but inside the three degree circle
are assigned to subsample B.
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See also:
VII/144 : The CfA redshift catalogue (Huchra et al., 1992))
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1-10 A10 --- Cluster *MKW or AWM cluster number
11-25 A15 --- Galaxy *Name of the galaxy
26-35 A10 --- ID *Galaxy identification number with sample
36-38 I3 h RAh Right ascension 1950.0
39-43 F5.1 min RAm R.A.
45 A1 --- DE- Declination sign 1950.0
46-47 I2 deg DEd Dec.
48-50 I3 arcmin DEm Dec.
51-55 F5.1 mag mB0 ? Apparent magnitude on Zwicky B0 scale
56-61 I6 km/s RV Galaxy heliocentric radial velocity
62-65 I4 km/s e_RV Galaxy heliocentric radial velocity error
67-71 A5 --- Source *Source codes
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Note on Cluster:
MKW is the list by Morgan, Kayser and White [1975ApJ...199..545M];
AWM is the list by Albert, White and Morgan [1977ApJ...211..309A]
Note on Galaxy:
The galaxy name is repeated when several measurements exist.
Note on ID:
This is the number of each galaxy within the sample followed by a
subsample descriptor. Lower case letters a and b refer to redshifts
which appear in two different subsamples according to:
a Galaxies in common MKW 6 & MKW7/8
b Galaxies in common MKW 4s & AWM 2
Note on Source:
Codes given in Huchra et al. [1992BICDS..41...31H] or:
-4 Bothun 1991, private communication
-4-1 Mould 1991, private communication
-4-2 Mould et al. 1991, private communication
-5-2 Strauss et al. 1994, private communication
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Origin: AAS CD-ROM series, Volume 4, 1995 Lee Brotzman [ADS] 03-May-1995
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(End) [CDS] 11-Jul-1995