J/AJ/161/41 Internal kinematics of 9 globular clusters with HST (Cohen+, 2021)
Structure and internal kinematics of nine inner Milky Way globular clusters.
Cohen R.E., Bellini A., Libralato M., Correnti M., Brown T.M., Kalirai J.S.
<Astron. J., 161, 41 (2021)>
=2021AJ....161...41C 2021AJ....161...41C
ADC_Keywords: Milky Way; Clusters, globular; Photometry, HST; Optical;
Proper motions
Keywords: Globular star clusters ; Star clusters ; Stellar dynamics
Abstract:
This study constitutes part of a larger effort aimed at better
characterizing the Galactic globular clusters (GGCs) located toward
the inner Milky Way bulge and disk. Here, we focus on internal
kinematics of nine GGCs, obtained from space-based imaging over time
baselines of >9yr. We exploit multiple avenues to assess the dynamical
state of the target GGCs, constructing radial profiles of projected
stellar density, proper motion dispersion, and anisotropy. We posit
that two-thirds (6/9) of our target GGCs are in an advanced dynamical
state, and are close to (or have recently undergone) core-collapse,
supported by at least two lines of evidence. First, we find relatively
steep proper motion dispersion profiles, in accord with literature
values for core-collapsed GGCs. Second, we find that our sample is, in
the mean, isotropic even out to their half-light radii, although one
of our target clusters (NGC6380) is tangentially anisotropic at
>1σ beyond its half-light radius, in accord with theoretical
predictions for clusters evolving in strong tidal fields. Our proper
motion dispersion and anisotropy profiles are made publicly available.
Description:
We have obtained second-epoch photometry of all nine of these
clusters, between 2003 July and 2019 August, with the Advanced Camera
for Surveys/Wide Field Camera (ACS/WFC) onboard Hubble Space Telescope
(HST) in the F606W and F814W filters (GO-15065, PI:Cohen).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 60 107 Radial proper motion dispersion and anisotropy
profiles
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
VII/195 : Globular Clusters in the Milky Way (Harris, 1996)
VII/202 : Globular Clusters in the Milky Way (Harris, 1997)
J/AJ/109/218 : Catalogue of globular cluster profiles (Trager+ 1995)
J/ApJS/161/304 : Star clusters in Milky Way & satellites (McLaughlin+, 2005)
J/AJ/132/447 : Surface Brightness 38 Gal. Globular Clusters (Noyola+, 2006)
J/AJ/131/2114 : Radial velocities in Fornax dSph (Walker+, 2006)
J/AJ/133/1658 : ACS survey of galactic globular clusters (Sarajedini+, 2007)
J/AJ/133/1287 : JHK photometry 24 Galactic globular clusters (Valenti+,2007)
J/ApJ/710/1032 : Proper motions in ω Cen (Anderson+, 2010)
J/MNRAS/402/1729 : JHK photometry 36 Galactic globular clusters (Valenti+,2010)
J/ApJ/797/115 : HSTPROMO I. Observations and NGC7078 results (Bellini+,2014)
J/MNRAS/444/392 : Synthetic Stellar Photometry. I. (Casagrande+, 2014)
J/AJ/149/99 : VVV globulars I 2MASS-GC 02, Terzan 10 (Alonso-Garcia+,2015)
J/ApJ/803/29 : HSTPROMO catalogs. II. Kinematic profiles (Watkins+, 2015)
J/ApJ/812/149 : HSTPROMO. III. Dynamical distances (Watkins+, 2015)
J/ApJ/842/6 : Astro-photometric catalog of core of NGC5139 (Bellini+,2017)
J/ApJ/853/86 : HST large programme on ω Centauri. II. (Bellini+,2018)
J/ApJ/861/99 : HSTPROMO cat VI Improved analysis NGC362 (Libralato+, 2018)
J/MNRAS/482/5138 : Galactic GC mean pm & velocities (Baumgardt+, 2019)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- ID Target cluster identifier
9- 10 I2 --- Bin [1/19] Radial bin number
12- 17 F6.3 arcsec Radmin [0.04/84.7] Minimum bin radius
19- 24 F6.3 arcsec Rad [2/98] Bin radius
26- 32 F7.3 arcsec Radmax [2.9/126] Maximum bin radius
34- 36 I3 --- N [19/912] Number of stars in bin
38- 42 F5.3 mas/yr pmDisp [0.07/0.2] 1D proper motion dispersion
44- 48 F5.3 mas/yr e_pmDisp [0.003/0.02] Uncertainty in pmDisp
50- 54 F5.3 --- Aniso [0.8/1.4] Anisotropy (1)
56- 60 F5.3 --- e_Aniso [0.03/0.33] Uncertainty in Aniso
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Note (1): Ratio of tangential to radial proper motion dispersion.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 03-Mar-2021