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J/AJ/113/483 Groups of Galaxies (Ramella+ 1997)
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Groups of Galaxies in the Northern CfA Redshift Survey
Ramella M., Pisani A., Geller M.J.
<Astron. J. 113, 483 (1997)>
=1997AJ....113..483R
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ADC_Keywords: Galaxy catalogs ; Velocity dispersion
Abstract:
We use a friends-of-friends algorithm to identify loose groups from
the northern CfA2 survey covering the region 8h<={alpha}_(1950)_<=17h
and 8.5{deg}<={delta}_(1950)_<=44.5{deg}. There are 406 groups; 149 of
these contains five or more members within the survey. Geometric
simulations guide our choice of the selection parameters;
{delta}{rho}/{rho}=80 is the limiting density contrast and V0=350km/s
is the fiducial velocity linking parameter. The geometric simulations
are particularly important for evaluating the impact of large-scale
structure (e.g., the Great Wall) on group selection. The physical
parameters of this large sample are coincident with our earlier
results [126 groups in Ramella et al. (1989ApJ...344...57R)]: the
median velocity dispersion in 192 (156; 229)km/s and the median blue
log(M/L) is 2.38 (2.20; 2.52). The mass-to-light ratio (M/L) is in
units of Msun/Lsun for an assumed Hubble constant, H0=100km/s/Mpc. The
numbers in parentheses are 99% confidence limits. This group catalog
provides a substantially larger sample for statistical studies than
has been previously available. For example, it provides a more
substantial sample for estimation of the distribution of group
velocity dispersions and of the group-group correlation function.
(Copyright) 1997 American Astronomical Society.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 66 406 List of the values of group parameters for
d{rho}/{rho}=80 and V_0_=350km/s
table1.tex 113 440 AASTeX version of table1.dat
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See also:
VII/193 : ZCat (The CfA Redshift Catalogue) Version June 1995 (Huchra+ 1995)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID Identification of group
5- 7 I3 --- Nmemb Number of members
10- 11 I2 h RAh Mean right ascension 1950
13- 16 F4.1 min RAm Mean right ascension 1950
18 A1 --- DE- Sign declination (always blank)
19- 20 I2 deg DEd Mean declination 1950
22- 25 F4.1 arcmin DEm Mean declination 1950
27- 31 I5 km/s cz Mean redshift of members
33- 36 I4 km/s e_cz Velocity dispersion
38- 42 F5.2 [solLum] log(L) Log of total luminosity
44- 48 F5.3 Mpc Rh Virial radius
50- 54 F5.3 --- t(cr) Crossing time (in units of Hubble time)
56- 60 F5.2 [solMass] log(M) Log of virial mass
62- 66 F5.2 [Sun] log(M/L) Log of mass-to-light ratio
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Origin: AAS CD-ROM series, Volume 8, 1997 Lee Brotzman [ADS] 04-Apr-1997
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(End) [CDS] 03-Jul-1997