J/ApJ/839/89 5 Galactic GC proper motions from Gaia DR1 (Watkins+, 2017)
Tycho-Gaia Astrometric Solution parallaxes and proper motions for five Galactic
globular clusters.
Watkins L.L., van der Marel R.P.
<Astrophys. J., 839, 89 (2017)>
=2017ApJ...839...89W 2017ApJ...839...89W
ADC_Keywords: Clusters, globular ; Parallaxes, trigonometric ; Proper motions ;
Radial velocities
Keywords: globular clusters: general ; parallaxes ; proper motions ;
stars: kinematics and dynamics
Abstract:
We present a pilot study of Galactic globular cluster (GC) proper
motion (PM) determinations using Gaia data. We search for GC stars in
the Tycho-Gaia Astrometric Solution (TGAS) catalog from Gaia Data
Release 1 (DR1), and identify five members of NGC 104 (47 Tucanae),
one member of NGC 5272 (M3), five members of NGC 6121 (M4), seven
members of NGC 6397, and two members of NGC 6656 (M22). By taking a
weighted average of member stars, fully accounting for the
correlations between parameters, we estimate the parallax (and, hence,
distance) and PM of the GCs. This provides a homogeneous PM study of
multiple GCs based on an astrometric catalog with small and
well-controlled systematic errors and yields random PM errors similar
to existing measurements. Detailed comparison to the available Hubble
Space Telescope (HST) measurements generally shows excellent
agreement, validating the astrometric quality of both TGAS and HST. By
contrast, comparison to ground-based measurements shows that some of
those must have systematic errors exceeding the random errors. Our
parallax estimates have uncertainties an order of magnitude larger
than previous studies, but nevertheless imply distances consistent
with previous estimates. By combining our PM measurements with
literature positions, distances, and radial velocities, we measure
Galactocentric space motions for the clusters and find that these also
agree well with previous analyses. Our analysis provides a framework
for determining more accurate distances and PMs of Galactic GCs using
future Gaia data releases. This will provide crucial constraints on
the near end of the cosmic distance ladder and provide accurate GC
orbital histories.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 122 26 TGAS from Gaia DR1 star properties and membership
selection statistics
table2.dat 71 5 TGAS parallax and proper motion results
table3.dat 40 5 Additional cluster properties for space motion
analysis
table4.dat 133 5 Cluster space motions and orbits
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See also:
VII/195 : Globular Clusters in the Milky Way (Harris, 1996)
I/259 : The Tycho-2 Catalogue (Hog+ 2000)
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
III/279 : RAVE 5th data release (Kunder+, 2017)
J/ApJ/420/612 : Proper motions & radial velocities in M22 (Peterson+ 1994)
J/ApJ/443/124 : Radial Velocities of Stars in M4 (Peterson+ 1995)
J/MNRAS/349/1278 : BVI photometry of M22 (Monaco+, 2004)
J/ApJS/161/304 : Star clusters in the MW and satellites (McLaughlin+, 2005)
J/AJ/143/50 : White dwarfs in 47 Tuc (NGC 104) with HST (Woodley+, 2012)
J/AJ/145/43 : CASE. V. Three eclipsing binaries in M4 (Kaluzny+, 2013)
J/ApJ/797/115 : HSTPROMO I. Obs. and NGC7078 results (Bellini+, 2014)
J/A+A/573/A115 : Radial velocities in seven globular clusters (Lardo+, 2015)
J/ApJ/808/11 : RR Lyrae stars in M4. II. Spitzer/IRAC phot. (Neeley+, 2015)
J/ApJ/812/149 : HSTPROMO. III. Dynamical distances (Watkins+, 2015)
J/ApJ/803/29 : HSTPROMO catalogs. II. Kinematic profiles (Watkins+, 2015)
http://www.astro.yale.edu/dana/gc.html : Absolute PM of globular clusters
http://www.cosmos.esa.int/web/gaia : ESA Gaia science community home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GID Gaia identifier (<Gaia DR1 NNNN...NNN> in Simbad)
21- 27 F7.2 deg RAdeg Right ascension (J2000)
29- 35 F7.2 deg DEdeg Declination (J2000)
39- 44 F6.3 mas Plx Parallax
47- 52 F6.2 mas/yr pmRA [-13.5/10.4] Proper motion in RA µα*
55- 60 F6.2 mas/yr pmDE [-19.5/-1.1] Proper motion in DEC µδ
64- 68 F5.2 mag BTmag [11.7/14.8] Tycho2 B-band magnitude
72- 76 F5.2 mag VTmag [10.1/12.5] Tycho2 V-band magnitude
78- 84 F7.2 km/s RV [-149/70]? Radial velocity from RAVE
86- 88 A3 --- --- [NGC]
90- 93 I4 --- NGC Nearest cluster name
97-102 F6.3 [-] logLad [-7/-0.01] Logarithm of position likelihood
106-111 F6.3 [-] logLpmu [-9/-0.9] Logarithm of parallax and PM likelihood
114-120 F7.3 [-] logLi [-10.7/-1] Logarithm of total likelihood
122-122 A1 --- Mm [*] *: cluster member (1)
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Note (1): Stars marked "*" are those we identify as cluster members and use
in Section 3 to derive the cluster properties in Table 2.
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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 A3 --- --- [NGC]
5- 8 I4 --- NGC Cluster name
10- 14 F5.3 mas plx [0.2/0.6] Parallax estimate
16- 21 F6.2 mas/yr pmRA [-13/9] Proper motion along Right Ascension
23- 28 F6.2 mas/yr pmDE [-19/-2.8] Proper motion along Declination
30- 34 F5.3 mas e_plx [0.1/0.3] Uncertainty in plx
36- 39 F4.2 mas/yr e_pmRA [0.5/1.5] Uncertainty in pmRA
41- 44 F4.2 mas/yr e_pmDE [0.2/1.5] Uncertainty in pmDE
46- 51 F6.3 --- Cplx-pmRA [-0.5/0.6] Correlation between plx and pmRA
53- 58 F6.3 --- Cplx-pmDE [-0.6/0.6] Correlation between plx and pmDE
60- 65 F6.3 --- CpmRA-pmDE [-0.4/1] Correlation between pmRA and pmDE
67- 71 F5.3 --- pplx [0.4/1] The p-value for plx
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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- 3 A3 --- --- [NGC]
5- 8 I4 --- NGC Cluster name
10-16 F7.3 deg RAdeg Right ascension (J2000)
18-24 F7.3 deg DEdeg Declination (J2000)
26-30 F5.2 kpc Dist [1.8/10.1] Distance
32-35 F4.2 kpc e_Dist [0.05/0.9] Negative uncertainty on Dist
37-40 F4.2 kpc E_Dist [0.05/1] Positive uncertainty on Dist
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [NGC]
5- 8 I4 --- NGC Cluster name
10- 14 F5.2 kpc X X position coordinate
16- 20 F5.2 kpc Y Y position coordinate
22- 26 F5.2 kpc Z Z position coordinate
28- 34 F7.2 km/s U [-149/56] U velocity component
36- 40 F5.2 km/s e_U Uncertainty in U
42- 47 F6.2 km/s V [50/213] V velocity component
49- 53 F5.2 km/s e_V Uncertainty in V
55- 61 F7.2 km/s W [-133/69] W velocity component
63- 67 F5.2 km/s e_W Uncertainty in W
69- 74 F6.2 km/s v [74/286] Magnitude of total velocity
76- 80 F5.2 km/s e_v Uncertainty in v
82- 88 F7.2 km/s vrad [-123/179] Radial component of velocity (1)
90- 94 F5.2 km/s e_vrad Uncertainty in vrad
96-101 F6.2 km/s vtan [48/224] Tangential component of velocity (1)
103-107 F5.2 km/s e_vtan Uncertainty in vtan
109-114 F6.2 km/s Pi [-58/170] Radial component of velocity (2)
116-120 F5.2 km/s e_Pi Uncertainty in Pi
122-127 F6.2 km/s Theta [47/197] Tangential component of velocity (2)
129-133 F5.2 km/s e_Theta Uncertainty in Theta
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Note (1): In a spherical coordinate system.
Note (2): In a cylindrical coordinate system.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 23-Nov-2017