J/AJ/108/2087 Globular Clusters in Ellipticals (Ajhar+ 1994)
VRI Photometry of Globular Clusters in Virgo and Leo Ellipticals
Ajhar E.A., Blakeslee J.P., Tonry J.L.
<Astron. J. 108, 2087 (1994)>
=1994AJ....108.2087A 1994AJ....108.2087A
ADC_Keywords: Galaxies, optical; Clusters, globular; Photometry
Abstract:
We present VRI photometry for the globular cluster systems (GCS's) of
ten elliptical and S0 galaxies in Virgo and Leo. We find that the V-I
color (metallicity) distributions are quite different from galaxy to
galaxy. One extreme is represented by NGC 4374 with a narrow, blue
distribution. NGC 4472 has a very broad, uniform distribution in
color, corresponding to -1.8 < [Fe/H] < +0.47. At the other extreme is
NGC 4365, which is weighted towards red colors, and possibly has a
peculiar luminosity function. We suggest that this variation of GCS
metallicity depends on environment, with formation of high metallicity
globular clusters inhibited in higher density environments. We compare
color-color plots of the GCS's of these galaxies with the Milky Way GCS
and with integrated isochrones. We find good agreement with the
galaxies studied here except that the isochrones predict colors which
are slightly too bright in the I band for metal-rich clusters. We also
consider the radial GC color distributions in these galaxies. We find
evidence for a V-I color gradient only in NGC 4374, in the sense of
redder clusters toward the center of the galaxy but warn that possible
systematic effects must be ruled out with the new data. Lastly, using
the surface brightness fluctuation distances to these galaxies, we find
supporting evidence for the universality of the globular cluster
luminosity function.
Description:
Tables 3-12 contain the positions, radial distances, magnitudes, and
colors of objects located for each galaxy. Only objects brighter
than R=22 and classified by DOPHOT as point sources in the V, R, and
I images are included in the tables. The positions are in arcseconds
and are relative to the center of the galaxy such that +x is to the
west and +y is to the north. The magnitude and colors of each object
have been corrected for reddening and absorption according to
Equation (1) of the paper and following the values listed in Table 2
of the paper. Please use those values to recover the actual apparent
magnitudes of these objects if desired.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 41 60 NGC 3379
table4.dat 41 142 NGC 4365
table5.dat 41 119 NGC 4374
table6.dat 41 105 NGC 4406
table7.dat 41 29 NGC 4458
table8.dat 41 21 NGC 4468
table9.dat 41 170 NGC 4472
table10.dat 41 16 NGC 4489
table11.dat 41 127 NGC 4552
table12.dat 41 26 NGC 4578
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Byte-by-byte Description of file: *.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID Identification number
4-10 F7.1 arcsec Xpos X position relative to center of galaxy
11-17 F7.1 arcsec Ypos Y position relative to center of galaxy
18-23 F6.1 arcsec Dist Radial distance
24-29 F6.2 mag Rmag R magnitude
30-35 F6.3 mag V-R V-R color
36-41 F6.3 mag R-I R-I color
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Origin: AAS CD-ROM series, Volume 4, 1995 Lee Brotzman [ADS] 24-Apr-1995
(End) [CDS] 10-Jul-1995