J/ApJ/513/733 Globular cluster system in M87 (Kundu+, 1999)
The globular cluster system in the inner region of M87.
Kundu A., Whitmore B.C., Sparks W.B., Macchetto F.D., Zepf S.E.,
Ashman K.M.
<Astrophys. J. 513, 733 (1999)>
=1999ApJ...513..733K 1999ApJ...513..733K
ADC_Keywords: Clusters, globular ; Photometry
Keywords: galaxies: individual (M87) - galaxies: star clusters - surveys
Abstract:
We have identified 1057 globular cluster candidates in a WFPC2 image
of the inner region of M87. The globular cluster luminosity function
(GCLF) can be well fitted by a Gaussian profile with a mean value of
m0V=23.67±0.07mag and σ=1.39±0.06mag. The GCLF in five
radial bins is found to be statistically the same at all points,
showing no clear evidence of dynamical destruction processes based on
the luminosity function (LF). Similarly, there is no obvious trend
between the half-light radius of the clusters and the galactocentric
distance. The core radius of the globular cluster density distribution
is Rc=56", considerably larger than the core of the stellar
component (Rc=6.8"). The mean color of the cluster candidates is
V-I=1.09mag, which corresponds to an average metallicity of
Fe/H=-0.74dex. The color distribution is bimodal everywhere, with a
blue peak at V-I=0.95mag and a red peak at V-I=1.20mag. The red
population is only 0.1mag bluer than the underlying galaxy, indicating
that these clusters formed late in the metal-enrichment history of the
galaxy and were possibly created in a burst of star/cluster formation
3-6Gyr after the blue population. We also find that both the red and
the blue cluster distributions have a more elliptical shape (Hubble
type E3.5) than the nearly spherical galaxy. The average half-light
radius of the clusters is ∼2.5pc, which is comparable to the 3pc
average effective radius of the Milky Way clusters, although the red
clusters are ∼20% smaller than the blue ones.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 45 100 Positions, magnitudes, and colors of the
hundred objects closest to the nucleus of M87
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [KWS99] Identification number ([KWS99] NNN in Simbad)
5- 10 F6.2 arcsec oRA Offset in right ascension (1)
12- 17 F6.2 arcsec oDE Offset in declination (1)
19- 23 F5.2 arcsec Rad Radial distance of the cluster candidate from
the center of M87
25- 29 F5.2 mag Vmag Johnson V magnitude
31- 35 F5.2 mag Imag Cousins Ic magnitude
37- 40 F4.2 mag V-Ic V-Ic colour index
42- 45 F4.2 mag e_V-Ic rms uncertainty on V-Ic
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Note (1): Offsets from the observed center of M87 at
RA=12:30:49.48, DE=12:23:29.38 (J2000)
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History:
From ApJ electronic version
(End) James Marcout, Patricia Bauer [CDS] 27-May-1999