Grupo de Sistemas Estelares

Delgado, A. J. and Alfaro, E. J.
The Astronomical Journal, Volume 119, Issue 4, pp. 1848-1854.
04/2000

ABSTRACT

Photometric CCD UBV measurements have been obtained in the field of the young Cygnus cluster NGC 6910. The observations reach down to magnitude V~=18 for 206 stars measured in all three UBV bands, uncovering the region of the color-magnitude diagram where pre-main-sequence (PMS) stars are expected. The transformation of our instrumental magnitudes to the standard system is discussed on the basis of two different sets of standard stars: 22 stars from six fields in the Landolt catalogs and 48 stars with published photoelectric photometry in common with ours in the four clusters observed in this campaign. The latter set is preferred, since it enables the effect of systematic errors in the U-B colors to be minimized. The adopted cluster parameters are E(B-V)=1.02+/-0.13, V₀-M_V=11.2+/-0.2, and age=(6.5+/-3)x10⁶ yr. The search for PMS cluster members on the basis of the calculated color excess and distance modulus results in the proposed membership for 11 PMS stars of spectral types from A to G.