J/ApJ/471/694 Abell 2390 Gunn photometry and equivalent widths (Abraham+ 1996)
Galaxy evolution in Abell 2390.
Abraham R.G., Smecker-Hane T.A., Hutchings J.B., Carlberg R.G.,
Yee H.K.C., Ellingson E., Morris S., Oke J.B., Rigler M.
<Astrophys. J. 471, 694 (1996)>
=1996ApJ...471..694A 1996ApJ...471..694A (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Galaxies, photometry ; Equivalent widths
Keywords: galaxies: clusters: individual (Abell 2390) -
galaxies: distances and redshifts - galaxies: photometry -
galaxies: stellar content
Abstract:
The galaxy population in the intermediate-redshift (z=0.228) rich
cluster Abell 2390 is investigated. We present velocities, colors, and
morphological information for an exceptionally large sample of 323
galaxies (216 cluster members) in a 46'x7' (6h-1Mpcx1h-1Mpc) strip
centered on the cD galaxy. This sample of confirmed cluster members is
second only to that for the Coma cluster in terms of sample size and
spatial coverage in the cluster rest frame and it is the first to
trace the transition between a rich cluster and the field at
intermediate redshift. The galaxy population in the cluster changes
gradually from a very evolved, early-type population in the inner
0.4h-1Mpc of the cluster to a progressively later type population in
the extensive outer envelope of the cluster from 1 to 3h-1Mpc in
radius. Radial gradients in galaxy gr color, 4000Å break, Hδ
and [O II] line strengths, and morphology are seen in the cluster and
are investigated by comparing the data to models computed with the
GISSEL spectral synthesis package. The results suggest that the
cluster has been built up gradually by the infall of field galaxies
over ∼8Gyr and that star formation has been truncated in infalling
galaxies during the accretion process. The morphological composition
of the cluster is shown to be consistent with such a scenario. If true
for other clusters, infall-truncated star formation as seen in
Abell 2390 may explain both the Butcher-Oemler effect and the large
fraction of S0 galaxies in clusters. Only <5% of the galaxies observed
in Abell 2390 exhibit evidence for star formation at levels stronger
than those seen in typical late-type systems. This suggests that
starbursts do not play a major role in driving cluster galaxy
evolution at the redshift of Abell 2390, although infall-induced
starbursts leading to truncated star formation may have played a role
in the earlier history of the cluster. Evidence is found for at least
one subcomponent on the west side of the cluster, which is likely to
be infalling at the epoch of observation.
For a description of the Gunn photometric system, see e.g. GCPD/38
Objects:
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RA (2000) DE Designation(s)
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21 53.6 +17 40 ACO 2390
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 104 323 Abell 2390 catalog
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See also:
J/ApJS/102/289 : CNOC cluster redshift survey catalogs. II. (Yee+, 1996)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- Yee Identification number from Yee et al.
(1995ASPC...86..301Y 1995ASPC...86..301Y)
8- 12 F5.2 mag rmag Gunn r-band magnitude
14- 18 F5.2 mag g-r ? Gunn g-r color
20- 23 F4.2 mag e_g-r rms uncertainty on g-r
25- 30 F6.1 arcsec Rad Projected radius from central cD
32- 37 F6.4 --- z Redshift
39- 42 F4.1 --- S/N ? Signal-to-noise ratio at uniform rest
wavelength (see text).
44- 49 F6.2 0.1nm D4000 ? 4000 Angstroms break
51- 55 F5.2 0.1nm e_D4000 ? rms uncertainty on D4000
57- 61 F5.1 0.1nm Hd ? Hδ equivalent width
63- 66 F4.1 0.1nm e_Hd ? rms uncertainty on Hd
68- 73 F6.1 0.1nm [OII] ? [O II] λ3727 equivalent width (1)
75- 78 F4.1 0.1nm e_[OII] ? rms uncertainty on [OII]
80- 83 F4.2 --- C ? Morphological index (2)
85- 88 F4.2 --- e_C ? rms uncertainty on C
90- 93 F4.1 mag/arcsec2 mur ? Limiting isophote of galaxy image
95-100 A6 --- Memb Cluster membership classification (3)
102-104 A3 --- Blue [yes no] Blueness classification (4)
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Note (1): Only definite 2σ detections are listed.
Note (2): C is the galaxy's central concentration of light. See Doi et al.,
1993MNRAS.264..832D 1993MNRAS.264..832D for the complete description of the
classification.
Note (3): field: field galaxy
member: cluster member galaxy
near: near-field galaxy
Note (4): Blue object are defined to be those galaxies at least 0.25mag bluer
in g-r than the color of the red galaxy locus at the projected radius
of each individual galaxy.
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History: Prepared via OCR at CDS.
(End) James Marcout, Patricia Bauer [CDS] 26-Feb-1998