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Astron. Astrophys. 318, 29-36 (1997)

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Identification of moving groups from a sample of B, A and F type stars

B. Chen , R. Asiain , F. Figueras and J. Torra

Departament d'Astronomia i Meteorologia, Universitat de Barcelona, Avda. Diagonal 647, E-08028, Barcelona, Spain

Received 16 April 1996 / Accepted 22 May 1996


An algorithm to find moving groups has been developed and applied to a sample of 1924 B, A, and F main sequence stars, basically extracted from the Hipparcos Input Catalogue. This algorithm uses a non-parametric kernel estimator to describe the stellar distribution in a 4-dimensional space of velocities and age, although it can be used to detect the real clustering structure in an n-dimensional space automatically.

Four moving groups near the Sun (Pleiades, Sirius, Hyades, IC2391) have been identified without assuming any a priori knowledge of moving groups, neither the velocity distribution nor other physical properties. This provides objective evidence of the existence of the moving groups, and we find that about 26% of our sample belongs to such stellar streams. For the remaining field stars we obtain a mean motion of the Sun respect to the Local Standard of Rest (U,V,W) = (13.4 [FORMULA] 0.4, 11.1 [FORMULA] 0.3, 6.9 [FORMULA] 0.2) km s-1.

Key words: stars: early-type – stars: statistics – (Galaxy): solar neighbourhood – stars: kinematics

Send offprint requests to: B. Chen (bchen@mizar.am.ub.es)

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© European Southern Observatory (ESO) 1997

Online publication: July 8, 1998