New β Cephei variable in the Southern open cluster NGC 6200: ALS 3728

Abstract We report the evidence of a new β Cephei type variable located in the Southern open cluster NGC 6200: ALS 3728. Spectroscopic and photometric observations of NGC 6200 stars were carried out at the South African Astronomical Observatory (SAAO) in 2011. It was found that ALS 3728 has a frequency of about 4.95 d−1 with highest amplitude. The star also shows a remarkable stillstand phase just before its light maxima which is a typical characteristic occurring among these type of stars. Furthermore, a mode identification is applied for the dominant frequency calculated from the Fourier analysis.