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J/MNRAS/399/2146    Orbits of open clusters in the Galaxy          (Wu+, 2009)

The orbits of open clusters in the Galaxy. Wu Z.-Y., Zhou X., Ma J., Du C.-H. <Mon. Not. R. Astron. Soc., 399, 2146-2164 (2009)> =2009MNRAS.399.2146W
ADC_Keywords: Clusters, open ; Radial velocities ; Proper motions ; Space velocities Keywords: Galaxy: disc - Galaxy: kinematics and dynamics - open cluster and associations: general Abstract: We present and analyse the kinematics and orbits for a sample of 488 open clusters (OCs) in the Galaxy. The velocity ellipsoid for our present sample is derived as (σ(U),σ(V),σ(W)) = (28.7, 15.8, 11.0)km/s which represents a young thin-disc population. We also confirm that the velocity dispersions increase with the age of a cluster subsample. The orbits of OCs are calculated with three Galactic gravitational potential models. The errors of orbital parameters are also calculated considering the intrinsic variation of the orbital parameters and the effects of observational uncertainties. The observational uncertainties dominate the errors of derived orbital parameters. The vertical motions of clusters calculated using different Galactic disc models are rather different. The observed radial metallicity gradient of clusters is derived with a slope of b=-0.070±0.011dex/kpc. The radial metallicity gradient of clusters based on their apogalactic distances is also derived with a slope of b=-0.082±0.014dex/kpc. The distribution of derived orbital eccentricities for OCs is very similar to that derived for the field population of dwarfs and giants in the thin disc. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 98 488 The observed data of 488 OCs in our sample table2.dat 89 488 The present positions and velocities of 488 OCs in our sample table4.dat 98 488 *The orbital parameters and their errors of 488 OCs in our sample
Note on table4.dat: calculated with the Allen and Santillan (1991RMxAA..22..255A) model.
See also: B/ocl : Optically visible open clusters and Candidates (Dias+ 2002-2010) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 17 A17 --- Name Cluster name 19- 20 I2 h RAh Right ascension (J2000) 22- 23 I2 min RAm Right ascension (J2000) 25- 26 I2 s RAs Right ascension (J2000) 28 A1 --- DE- Declination sign (J2000) 29- 30 I2 deg DEd Declination (J2000) 32- 33 I2 arcmin DEm Declination (J2000) 35- 36 I2 arcsec DEs Declination (J2000) 38- 43 F6.3 kpc Dist Heliocentric distance 45- 49 F5.3 kpc e_Dist rms uncertainty on Dist 51- 56 F6.1 km/s RV Radial velocity 58- 61 F4.1 km/s e_RV rms uncertainty on RV 63- 68 F6.2 mas/yr pmRA Absolute proper motion along RA (pmRA*cosDE) 70- 73 F4.2 mas/yr e_pmRA rms uncertainty on pmRA 75- 80 F6.2 mas/yr pmDE Absolute proper motion along DE 82- 85 F4.2 mas/yr e_pmDE rms uncertainty on pmDE 87- 92 F6.1 Myr Age ? Cluster age 94- 98 F5.2 [Sun] [Fe/H] ? Cluster metallicity
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 17 A17 --- Name Cluster name 19- 25 F7.3 kpc Xpos X coordinate in Galactic Plane 27- 31 F5.3 kpc e_Xpos rms uncertainty on Xpos 33- 38 F6.3 kpc Ypos Y coordinate in Galactic Plane 40- 44 F5.3 kpc e_Ypos rms uncertainty on Ypos 46- 51 F6.3 kpc Zpos Z coordinate above Galactic Plane 53- 57 F5.3 kpc e_Zpos rms uncertainty on Zpos 59- 64 F6.1 km/s Uvel U velocity 66- 69 F4.1 km/s e_Uvel rms uncertainty on Uvel 71- 75 F5.1 km/s Vvel V velocity 77- 79 F3.1 km/s e_Vvel rms uncertainty on Vvel 81- 85 F5.1 km/s Wvel W velocity 87- 89 F3.1 km/s e_Wvel rms uncertainty on Wvel
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 17 A17 --- Name Cluster name 19- 22 F4.1 kpc Ra Apogalactic distance 24- 27 F4.1 kpc e_Ra rms uncertainty on Ra 29- 32 F4.1 kpc Rp Perigalactic distance 34- 36 F3.1 kpc e_Rp rms uncertainty on Rp 38- 41 F4.2 --- e Orbital eccentricity 43- 46 F4.2 --- e_e rms uncertainty on e 48- 52 F5.2 kpc zmax Maximum distance above the Galactic plane 54- 58 F5.2 kpc e_zmax rms uncertainty on zmax 60- 65 F6.1 Myr Tp Orbital period 67- 71 F5.1 Myr e_Tp rms uncertainty on Tp Tp 73- 77 F5.1 Myr Tz Mean time interval of the cluster to cross the Galactic plane from one zmax to the other in the opposite direction 79- 83 F5.1 Myr e_Tz rms uncertainty on Tz 85- 91 F7.1 Jz z-component of the angular momentum vector (1) 93- 98 F6.1 e_Jz rms uncertainty on Jz
Note (1): Because of the right-handed orientation of the coordinate system adopted here, the negative Jz of the z-component of the angular momentum vector corresponds to prograde rotation in the Galaxy and vice versa.
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 12-Aug-2011
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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