2006A&A...445..545P -
Astronomy and Astrophysics, volume 445, 545-565 (2006/1-2)
Revisiting the population of Galactic open clusters.
PISKUNOV A.E., KHARCHENKO N.V., ROESER S., SCHILBACH E. and SCHOLZ R.-D.
Abstract (from CDS):
We present results of a study of the galactic open cluster population based on the all-sky catalogue ASCC-2.5 (
I/280A) compiled from Tycho-2, Hipparcos and other catalogues. The sample of optical clusters from ASCC-2.5 is complete up to about 850pc from the Sun. The symmetry plane of the clusters' distribution is determined to be at Z
0=-22±4pc, and the scale height of open clusters is only 56±3pc. The total surface density and volume density in the symmetry plane are Σ= 114kpc
–2 and D(Z
0)=1015kpc
–3, respectively. We find the total number of open clusters in the Galactic disk to be of order of 10
5 at present. Fluctuations in the spatial and velocity distributions are attributed to the existence of four open cluster complexes (OCCs) of different ages containing up to a few tens of clusters. Members in an OCC show the same kinematic behaviour, and a narrow age spread. We find, that the youngest cluster complex, OCC 1 (logt<7.9), with 19° inclination to the Galactic plane, is apparently a signature of Gould's Belt. The most abundant OCC 2 complex has moderate age (logt≃8.45). The clusters of the Perseus-Auriga group, having the same age as OCC 2, but different kinematics are seen in breaks between Perseus-Auriga clouds. The oldest (logt≃8.85) and sparsest group was identified due to a large motion in the Galactic anticentre direction. Formation rate and lifetime of open clusters are found to be 0.23±0.03kpc
–2Myr
–1 and 322±31Myr, respectively. This implies a total number of cluster generations in the history of the Galaxy between 30 to 40. We estimate that less than about 10% of the total Galactic stellar disk population has ever passed an open cluster membership.
Abstract Copyright:
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Journal keyword(s):
Galaxy: disk - Galaxy: kinematics and dynamics - open clusters and associations: general - solar neighbourhood - Galaxy: stellar content - Galaxy: structure
Simbad objects:
125
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