Waelkens, C. ; Lampens, P. ; Heynderickx, D. ; Cuypers, J. ; Degryse, K. ; Poedts, S. ; Polfliet, R. ; Denoyelle, J. ; van den Abeele, K. ; Rufener, F. ; Smeyers, P.

published in Astronomy and Astrophysics Supplement Series, 83, pp. 11-25 (1990)

Abstract: Results are presented of a campaign of photometric observations of stars in the double cluster h and Chi Persei that spanned eight years. The long-time scale of the data has made it possible to discover that at least half of the brighter stars in h and Chi Persei are variable stars. It appears that most of these variables are Be stars or related objects. Accurate color-magnitude diagrams for the brightest stars of the double cluster show that the reddening is not as uniform as was assumed so far; that the observed parameters of many stars are very much affected by the high rotational velocities, and thus cannot be easily interpreted in terms of physical quantities; and that the reported age and distance differences of both clusters are probably spurious. It is noted that the large intrinsic scatter of the colors and magnitudes of the h and Chi Persei stars casts doubt on the validity of photometric calibrations that rely heavily on observations of the double cluster.

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