Membership Determination of van den Bergh Open Clusters vdB92, vdB146 (NGC 7129) and vdB150

ORELLANA, ROSA BEATRIZ; DE BIASI, MARÍA SILVINA; PAIZ, LEONARDO GASTON

International Journal of Astronomy and Astrophysics

Scientific Research

Año: 2017 vol. 07 p. 273 - 290

2161-4717

In this paper we study some van den Bergh open clusters combining photometryand astrometry. A model which analyses the proper motion distributionand the stellar density is applied to find the kinematic parameters andstellar membership in the region of the open clusters vdB92, vdB146 (NGC7129) and vdB150. The astrometric data are obtained from UCAC4 catalogue.The centre coordinates, the components of mean proper motion, the angulardiameter and the astrometric members are reported, taking the following values:for vdB92: α =105.97281 ± 0.13113 , δ = −11.57814 ± 0.10575 ,cos 3.46 0.19 mas yr α μ δ =− ± , 1.27 0.19 mas yr δ μ = ± , 34´, 60 members;for vdB146: α = 325.78423 ± 0.15297 , δ = 66.13575 ± 0.02907 ,cos 2.71 0.25 mas yr α μ δ =− ± , 3.32 0.25 mas yr δ μ =− ± , 9´, 5 members; andfor vdB150: α = 332.22519 ± 0.06074 , δ = 73.40232 ± 0.0.07789 ,cos 3.07 0.90 mas yr α μ δ = ± , 4.65 0.90 mas yr δ μ = ± , 15´, 7 members. Theincidence of the proper motion errors in the determination of the cluster parametersand of the stellar membership is analysed and it is found that they donot significantly change. We finally compare the astrometric members withthe photometric ones given in the literature.