J/MNRAS/407/2109 Kinematic study of open clusters (Vande Putte+, 2010)
A kinematic study of open clusters: implications for their origin.
Vande Putte D.V., Garnier T.P., Ferreras I., Mignani R.P., Cropper M.
<Mon. Not. R. Astron. Soc., 407, 2109-2121 (2010)>
=2010MNRAS.407.2109V 2010MNRAS.407.2109V
ADC_Keywords: Clusters, open ; Proper motions ; Space velocities
Keywords: Galaxy: formation - open clusters and associations: general
Abstract:
The Galactic population of open clusters provides an insight into star
formation in the Galaxy. The open cluster catalogue by Dias et al.
(Cat. B/ocl) is a rich source of data, including kinematic
information. This large sample made it possible to carry out a
systematic analysis of 481 open cluster orbits, using parameters based
on orbit eccentricity and separation from the Galactic plane. These
two parameters may be indicative of origin, and we find them to be
correlated. We also find them to be correlated with metallicity,
another parameter suggested elsewhere to be a marker for origin in
that high values of any of these two parameters generally indicate a
low metallicity ([Fe/H]solar←0.2dex). The resulting analysis points
to four open clusters in the catalogue being of extragalactic origin
by impact of high-velocity cloud on the disc: Berkeley 21, 32, 99 and
Melotte 66, with a possible further four due to this origin (NGC 2158,
2420, 7789 and IC 1311). A further three may be due to Galactic
globular cluster impact on the disc, i.e. of internal Galactic origin
(NGC 6791, 1817 and 7044).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 96 481 Observed data relevant to orbit calculations
table2.dat 90 481 Present positions and velocities of open
clusters, as calculated for use in the orbit code
table4.dat 53 481 Main orbital parameters for clusters
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See also:
B/ocl : Optically visible open clusters and Candidates (Dias+ 2002-2010)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq Sequential number
6- 22 A17 --- Name Cluster name
24- 25 I2 h RAh Right ascension (J2000)
27- 28 I2 min RAm Right ascension (J2000)
30- 31 I2 s RAs Right ascension (J2000)
33 A1 --- DE- Declination sign (J2000)
34- 35 I2 deg DEd Declination (J2000)
37- 38 I2 arcmin DEm Declination (J2000)
40- 41 I2 arcsec DEs Declination (J2000)
43- 47 I5 pc Dist Distance
49- 55 F7.1 pc e_Dist rms uncertainty on Dist
57- 64 F8.2 km/s RV Radial velocity
67- 71 F5.2 km/s e_RV ?=- rms uncertainty on RV
74- 79 F6.2 mas/yr pmRA Proper motion along RA, pmRA*cosDE
81- 84 F4.2 mas/yr e_pmRA ?=- rms uncertainty on pmRA
86- 91 F6.2 mas/yr pmDE Proper motion along DE
93- 96 F4.2 mas/yr e_pmDE ?=- rms uncertainty on pmDE
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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- 4 I4 --- Seq Sequential number
6- 11 F6.3 kpc x Galactocentric x position (1)
13- 17 F5.3 kpc e_x rms uncertainty on x
19- 24 F6.3 kpc y Galactocentric y position (1)
26- 30 F5.3 kpc e_y rms uncertainty on y
32- 37 F6.3 kpc z Galactocentric z position (1)
39- 43 F5.3 kpc e_z rms uncertainty on z
45- 51 F7.3 km/s dx/dt Velocity along x axis (1)
53- 58 F6.3 km/s e_dx/dt rms uncertainty on dx/dt
60- 67 F8.3 km/s dy/dt Velocity along y axis (1)
69- 74 F6.3 km/s e_dy/dt rms uncertainty on dy/dt
76- 83 F8.3 km/s dz/dt Velocity along z axis (1)
85- 90 F6.3 km/s e_dz/dt rms uncertainty on dz/dt
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Note (1): the galactocentric right-handed coordinate system is defined such
that the Sun position is (0,8kpc,0); the velocities in this system are
related to (U,V,W) velcoties with: dx/dt=V+220km/s, dy/dt=-U, dz/dt=W
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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- 4 I4 --- Seq Sequential number
6- 10 F5.2 kpc zmax Maximum height above the plane
12- 16 F5.2 kpc e_zmax rms uncertainty on zmax
18- 21 F4.2 --- eta Radial quantity (Rmax-Rmin)/(Rmax+Rmin)/2 (2)
23- 26 F4.2 --- e_eta rms uncertainty on eta
28- 32 F5.2 [Sun] [Fe/H] ?=- Metallicity
34- 37 F4.2 [Sun] e_[Fe/H] ?=- rms uncertainty on [Fe/H]
39- 43 F5.3 Gyr Age ?=- Age
45- 49 F5.3 Gyr e_Age ?=- rms uncertainty on Age
51- 53 I3 --- N* ?=- Number of cluster stars used to determine
the proper motion
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Note (2): Rmin and Rmax are the distance between the cluster and the
Galactic centre, projected onto the disk; this quantity is twice
the eccentricity for an elliptical orbit, and is small if the cluster
velocity is aligned with the local circular velocity.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 10-Mar-2011