J/ApJ/903/110 Radial velocity and g-i color in M85 globular clusters (Ko+, 2020)
Mysterious Globular Cluster System of the Peculiar Massive Galaxy M85.
Ko Y., Lee M.G., Park H.S., Sohn J., Lim S., Hwang N., Park B.-G.
<Astrophys. J., 903, 110 (2020)>
=2020ApJ...903..110K 2020ApJ...903..110K
ADC_Keywords: Clusters, globular; Photometry; Spectra, optical;
Spectra, infrared; Radial velocities
Keywords: Lenticular galaxies ; Elliptical galaxies ; Virgo Cluster ;
Globular star clusters
Abstract:
We present a study on the stellar population and kinematics of
globular clusters (GCs) in the peculiar galaxy M85. We obtain optical
spectra of 89 GCs at 8kpc<R<160kpc using the MMT/Hectospec. We divide
them into three groups, blue/green/red GCs (B/G/RGCs), with their
(g-i)0 colors. All GC subpopulations have mean ages of about 10Gyr,
but showing differences in metallicities. The BGCs and RGCs are the
most metal-poor ([Z/H]~-1.49) and metal-rich ([Z/H]~-0.45),
respectively, and the GGCs are in between. We find that the inner GC
system exhibits a strong overall rotation that is entirely due to a
disklike rotation of the RGC system. The BGC system shows little
rotation. The GGCs show kinematic properties clearly distinct among
the GC subpopulations, having higher mean velocities than the BGCs and
RGCs and being aligned along the major axis of M85. This implies that
the GGCs have an origin different from the other GC subpopulations.
The rotation-corrected velocity dispersion of the RGC system is much
lower than that of the BGC system, indicating the truncation of the
red halo of M85. The BGCs have a flat velocity dispersion profile out
to R=67kpc, reflecting the dark matter extent of M85. Using the
velocity dispersion of the BGC system, we estimate the dynamical mass
of M85 to be 3.8x1012M☉. We infer that M85 has undergone merging
events lately, resulting in the peculiar kinematics of the GC system.
Description:
The globular cluster (GC) candidates were identified as pointlike
sources in the ugi-band images taken with the MegaCam at the 3.8m
Canada-France-Hawaii Telescope. We used the (u-g)0 and (g-i)0 color
combination to select the GC candidates.
We carried out spectroscopic observations using the Hectospec mounted
on the 6.5m Multi Mirrors Telescope (MMT; Program ID: 2016A-UAO-G4,
PI: Youkyung Ko) during 2016 March. We selected a 270/mm grating with
a dispersion of 1.2Å/pixel, covering the wavelength range of
3650-9200Å. Three different configurations with a slight offset,
covering the R<30' region around M85, were made. We used the exposure
time of 7200s for each of the two configurations (M85-B1 and B2) to
cover bright targets, and we used the longer exposure time of 9000s
for one configuration (M85-F1) to cover fainter targets. The seeing
ranged from 0.9" to 1.3" during the observations.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 69 89 Spectroscopic and photometric properties of the
GCs confirmed in this study
table3.dat 70 420 Spectroscopic and photometric properties of
foreground stars and background galaxies in the
Hectospec field of M85
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See also:
J/AJ/90/1681 : The Virgo Cluster Catalog (VCC) (Binggeli+, 1985)
J/ApJS/94/687 : Old stellar populations. V. (Worthey+, 1994)
J/ApJ/459/110 : Line strengths and gradients in S0 galaxies (Fisher+ 1996)
J/AJ/113/950 : Kinematic Profiles of S0 Galaxies (Fisher 1997)
J/ApJS/111/377 : Hγ & Hδ absorption features (Worthey+ 1997)
J/ApJS/116/1 : Old Stellar Populations. VI. Absorption-Line (Trager+ 1998)
J/MNRAS/313/469 : Streaming motions of galaxy clusters. I. (Smith+, 2000)
J/MNRAS/330/547 : Local galaxy ages and metallicities (Terlevich+, 2002)
J/A+A/417/499 : Spectrophotometry of Virgo cluster galaxies (Gavazzi+, 2004)
J/ApJS/164/334 : ACS Virgo Cluster Survey. VI (Ferrarese+, 2006)
J/ApJS/182/216 : Surface photometry of Virgo ellipticals (Kormendy+, 2009)
J/MNRAS/398/91 : 2D kinematic structure of early-type galaxies (Proctor+, 2009)
J/ApJ/773/L27 : Globular clusters in ACSVCS early-type galaxies (Park+, 2013)
J/MNRAS/428/389 : SLUGGS globular clusters in early-type galaxies (Pota+, 2013)
J/MNRAS/442/3544 : Kinematic tracers in Umbrella galaxy (Foster+, 2014)
J/ApJS/215/22 : The Extended Virgo Cluster Catalog (EVCC) (Kim+, 2014)
J/MNRAS/446/120 : ATLAS3D project. XXIX (Duc+, 2015)
J/ApJ/872/202 : CFHT ugi photometry of globular clusters in M85 (Ko+, 2019)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- ID Identification
6- 15 F10.6 deg RAdeg [185/187] Right Ascension (J2000)
17- 25 F9.6 deg DEdeg [17.8/18.5] Declination (J2000)
27- 32 F6.3 mag imag [18.9/22] CFHT/MegaCam i band AB magnitude
34- 38 F5.3 mag e_imag [0.001/0.02] Error in imag
40- 44 F5.3 mag g-i [0.61/1.05] (g-i) color index, CFHT/MegaCam
AB system
46- 50 F5.3 mag e_g-i [0.002/0.02] Error in g-i
52- 56 F5.2 mag C [0/0.37] Inverse concentration index (1)
58- 61 I4 km/s RVel [351/1092] Heliocentric radial velocity
63- 65 I3 km/s e_RVel [9/135] Error in RVel
67- 69 A3 --- Class Classification (2)
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Note (1): The inverse concentration index C defined as the i-band magnitude
differences between 4- and 8-pixel-diameter aperture photometry.
Note (2): Class as follows:
BGC = blue GCs with (g-i)0<0.7 (41 occurrences)
GGC = green GCs with 0.7<(g-i)0<0.8 (32 occurrences)
RGC = red GCs with (g-i)0>0.8 (16 occurrences)
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- ID Identification
9- 18 F10.6 deg RAdeg [185/187] Right Ascension (J2000)
20- 28 F9.6 deg DEdeg [17.6/18.6] Declination (J2000)
30- 35 F6.3 mag imag [17.9/22.2] CFHT/MegaCam i band AB magnitude
37- 41 F5.3 mag e_imag [0.001/0.02] Error in imag
43- 47 F5.3 mag g-i [0.48/1.3] (g-i) color index, CFHT/MegaCam
AB system
49- 53 F5.3 mag e_g-i [0.001/0.03] Error in g-i
55- 59 F5.2 mag C [-0.04/0.56] Inverse concentration index (1)
61- 66 I6 km/s RVel [-251/151120] Heliocentric radial velocity
68- 70 I3 km/s e_RVel [4/131] Error in HRV
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Note (1): The inverse concentration index C defined as the i-band magnitude
differences between 4- and 8-pixel-diameter aperture photometry.
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History:
From electronic version of the journal
References:
Ko et al. Paper I : 2019ApJ...872..202K 2019ApJ...872..202K Cat. J/ApJ/872/202
(End) Prepared by [AAS], Coralie Fix [CDS], 07-Feb-2022