J/ApJ/703/42 HST photometry of M87 globular clusters (Peng+, 2009)
The color-magnitude relation for metal-poor globular clusters in M87:
confirmation from deep HST/ACS imaging.
Peng E.W., Jordan A., Blakeslee J.P., Mieske S., Cote P., Ferrarese L.,
Harris W.E., Madrid J.P., Meurer G.R.
<Astrophys. J., 703, 42-51 (2009)>
=2009ApJ...703...42P 2009ApJ...703...42P
ADC_Keywords: Clusters, globular ; Photometry, VRI ; Photometry, HST ;
Galaxies, photometry
Keywords: galaxies: dwarf - galaxies: elliptical and lenticular, cD -
galaxies: evolution - galaxies: individual (M87) -
galaxies: star clusters - globular clusters: general
Abstract:
We present a study of the M87 GC system using deep, archival HST/ACS
imaging with the F606W and F814W filters, in which we find a
significant color-magnitude relation for the metal-poor globular
clusters (GCs). The slope of this relation in the I versus V-I
color-magnitude diagram (γI=-0.024±0.006) is perfectly
consistent with expectations based on previously published results
using data from the ACS Virgo Cluster Survey. We show that previously
measured half-light radii of M87 GCs from best-fit PSF-convolved King
models are consistent with the more accurate measurements in this
study, and we also explain how the color-magnitude relation for
metal-poor GCs is real and cannot be an artifact of the photometry. We
fit Gaussian and evolved Schechter functions to the luminosity
distribution of GCs across all colors, as well as divided into blue
and red subpopulations, finding that the blue GCs have a brighter mean
luminosity and a narrower distribution than the red GCs. Finally, we
present a catalog of astrometry and photometry for 2250 M87 GCs.
Description:
M87 was observed for 50 orbits with the ACS Wide Field Channel (WFC)
in the F606W (V606) and F814W (I814) filters for a microlens
monitoring program (HST GO Program 10543, PI Baltz).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 53 2250 Positions and KINGPHOT photometry for M87 GCs
--------------------------------------------------------------------------------
See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
J/ApJ/671/1624 : NGC 1533 globular cluster candidates (Degraaff+, 2007)
J/AJ/131/866 : Hot populations in M87 globular clusters (Sohn+, 2006)
J/ApJ/613/279 : ACS Virgo Cluster Survey. III. M87 (Jordan+, 2004)
J/ApJ/559/812 : Globular cluster system in M87 (Hanes+, 2001)
J/ApJ/513/733 : Globular cluster system in M87 (Kundu+, 1999)
J/AJ/115/1801 : VRI photometry of M87 globular clusters (Harris+ 1998)
J/AJ/106/493 : Globular clusters in M87 (Lee+, 1993)
J/ApJS/73/671 : M87 globular clusters BVI photometry (Couture+, 1990)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- [PJB2009] Running identification number
6- 16 F11.7 deg RAdeg Right Ascension in decimal degrees (J2000)
18- 27 F10.7 deg DEdeg Declination in decimal degrees (J2000)
29- 34 F6.3 mag Vmag Converted V band magnitude (Vega) (1)
36- 40 F5.3 mag e_Vmag The 1σ uncertainty in Vmag
42- 47 F6.3 mag Imag Converted I band magnitude (Vega) (1)
49- 53 F5.3 mag e_Imag The 1σ uncertainty in Imag
--------------------------------------------------------------------------------
Note (1): We converted magnitudes to V and I by using the relation between
(V-I) and (mF606W-mF814W) presented in Equation (3) of DeGraaff et
al. (2007, Cat. J/ApJ/671/1624), namely
(V-I)=1.2(mF606W-mF814W)+0.06,
and the following equation from Table 22 in Sirianni et al.,
2005PASP..117.1049S 2005PASP..117.1049S; I=mF814W,OBMAG+25.495-0.002(V-I) (see section
3.1 for further details).
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 11-Oct-2011