J/A+A/486/85 Abell 496 low-luminosity early-type galaxies (Chilingarian+, 2008)
Kinematics and stellar populations of low-luminosity early-type galaxies in the
Abell 496 cluster.
Chilingarian I.V., Cayatte V., Durret F., Adami C., Balkowski C.,
Chemin L., Lagana T.F., Prugniel P.
<Astron. Astrophys., 486, 85-97 (2008)>
=2008A&A...486...85C 2008A&A...486...85C
ADC_Keywords: Clusters, galaxy ; Galaxies, photometry
Keywords: galaxies: elliptical and lenticular, cD - galaxies: dwarf -
galaxies: clusters: individual: Abell 496 -
galaxies: kinematics and dynamics - galaxies: stellar content -
galaxies: fundamental parameters
Abstract:
The morphology and stellar populations of low-luminosity early-type
galaxies in clusters have until now been limited to a few relatively
nearby clusters such as Virgo or Fornax. Scenarii for the formation
and evolution of dwarf galaxies in clusters are therefore not well
constrained.
We investigate here the morphology and stellar populations of
low-luminosity galaxies in the relaxed richness class 1 cluster
Abell 496 (z=0.0330).
Deep multiband imaging obtained with the CFHT Megacam allowed us to
select a sample of faint galaxies, defined here as objects with
magnitudes 18<r'<22mag within a 1.2arcsec fibre (-18.8<MB←15.1mag).
We observed 118 galaxies spectroscopically with the ESO VLT
FLAMES/Giraffe spectrograph with a resolving power R=6300. We present
structural analysis and colour maps for the 48 galaxies belonging to
the cluster. We fit the spectra of 46 objects with PEGASE. HR
synthetic spectra to estimate the ages, metallicities, and velocity
dispersions. We estimated possible biases by similarly analysing
spectra of ∼1200 early-type galaxies from the Sloan Digital Sky
Survey Data Release 6 (SDSS DR6). We computed values of α/Fe
abundance ratios from the measurements of Lick indices. We briefly
discuss effects of the fixed aperture size on the measurements.
Description:
We obtained images with the Canada France Hawaii Telescope with the
Megacam camera in the fall of 2003 (program 03BF12, P.I. V. Cayatte).
Megacam covers a field of 1°x1° on the sky, with a pixel size
of 0.187x0.187arcsec2. We obtained deep images in the u*, g', r',
and i' filters.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 99 48 B band absolute magnitudes, morphological
classification, detection of embedded
structures, and total magnitudes in 4 CFHT
bands for 48 Abell 496 galaxies
tablea2.dat 70 48 Projected distances, relative radial velocities
with respect to the cluster centre, and
structural parameters
tablea3.dat 87 48 *Selected Lick indices, values of derived values
of [Mg/Fe] using SSP models by Thomas et al.
(2003MNRAS.339..897T 2003MNRAS.339..897T) and brief comments
concerning structures seen in colour maps
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Note on tablea3.dat: For the 2 objects marked A1 and A2, no spectral fit
was possible.
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See also:
J/A+AS/139/525 : Abell 496 heliocentric velocities (Durret+, 1999)
J/A+AS/139/559 : Abell 496 photometric catalogue (Slezak+, 1999)
J/A+AS/140/155 : Abell 496 gri photometry (Moretti+, 1999)
J/A+A/393/439 : Catalogue of galaxies towards Abell 496 (Durret+, 2002)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- [CCD2008] Sequential number (G1)
4- 9 A6 --- --- [ACO496]
10- 28 A19 --- ACO496 ACO496 designation (JHHMMSS.ss+DDMMSS.s)
30- 35 F6.2 mag BMAG Absolute B magnitude
37- 44 A8 --- SpT Spectral type
46- 55 A10 --- embStr ?=- Embedded structures
57- 61 F5.2 mag u*mag Total u* magnitude
63- 66 F4.2 mag e_u*mag rms uncertainty on u*mag
68- 72 F5.2 mag g'mag Total g' magnitude
74- 77 F4.2 mag e_g'mag rms uncertainty on g'mag
79- 83 F5.2 mag r'mag Total r' magnitude
85- 88 F4.2 mag e_r'mag rms uncertainty on r'mag
90- 94 F5.2 mag i'mag Total i' magnitude
96- 99 F4.2 mag e_i'mag rms uncertainty on i'mag
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- [CCD2008] Sequential number (G1)
4- 7 I4 arcsec Dproj Projected distance from central cD galaxy
9- 13 I5 km/s DV Velocity difference (RV-V(A496))
15- 18 F4.2 arcsec reff Effective radius
20- 23 F4.2 arcsec e_reff rms uncertainty on reff
25- 29 F5.2 mag/arcsec+2 Mean effective surface brightness
in B within 1reff
31- 34 F4.2 mag/arcsec+2 e_ rms uncertainty on
36- 40 I5 km/s RV Radial velocity
42- 43 I2 km/s e_RV rms uncertainty on RV
45- 47 I3 km/s sigma ? Best-fitting velocity dispersion
49 I1 km/s e_sigma ? rms uncertainty on sigma
51- 54 F4.1 Gyr tau ? Best-fitting SSP-equivalent age
56- 58 F3.1 Gyr e_tau ? rms uncertainty on t
60- 64 F5.2 --- Z ? Best-fitting metallicity
66- 69 F4.2 --- e_Z ? rms uncertainty on Z
70 A1 --- Note [a] Note (1)
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Note (1): a = The values of reff and for G-20 in this table are
strongly discrepant with those presented in Chilingarian et al.
(2007A&A...466L..21C 2007A&A...466L..21C) measured on HST WFPC2, because here we did not
take into account seeing quality of our ground-based CFHT observations.
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Byte-by-byte Description of file: tablea3.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- [CCD2008] Sequential number (G1)
4- 9 F6.2 0.1nm Fe5015 ? Fe5015 Lick index
11- 14 F4.2 0.1nm e_Fe5015 ? rms uncertainty on Fe5015
16- 19 F4.2 0.1nm MgB ? MgB Lick index
21- 24 F4.2 0.1nm e_MgB ? rms uncertainty on MgB
26- 29 F4.2 0.1nm Fe5270 ? Fe5270 Lick index
31- 34 F4.2 0.1nm e_Fe5270 ? rms uncertainty on Fe5270
36- 39 F4.2 0.1nm Fe5335 ? Fe5335 Lick index
41- 44 F4.2 0.1nm e_Fe5335 ? rms uncertainty on Fe5335
46- 49 F4.2 0.1nm Fe5406 ? F35406 Lick index
51- 54 F4.2 0.1nm e_Fe5406 ? rms uncertainty on Fe5406
56- 60 F5.2 --- [Mg/Fe] ? Abundance [Mg/Fe]
62- 65 F4.2 --- e_[Mg/Fe] ? rms uncertainty on [Mg/Fe]
67- 87 A21 --- Com Comments
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Global notes:
Note (G1): [CCD2008] G-NN in Simbad.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 30-Sep-2008