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Astron. Astrophys. 345, 505-513 (1999)

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B-type pulsators in the central region of NGC 869 (h Persei)

J. Krzesiski 1,2, A. Pigulski 3 and Z. Kolaczkowski 3

1 Mt. Suhora Observatory, Cracow Pedagogical University, Podchoraych 2, PL-30-084 Kraków, Poland (sfkrzesi@cyf-kr.edu.pl)
2 Department of Astronomy, University of Cape Town, Rondebosch 7700, Cape Town, South Africa
3 Wroclaw University Observatory, Kopernika 11, PL-51-622 Wroclaw, Poland (pigulski; kolaczk@astro.uni.wroc.pl)

Received 21 December 1998 / Accepted 4 February 1999


In the course of the search for B-type pulsators in the central region of h Persei, we discovered two [FORMULA] Cephei stars, Oo 692 1 and Oo 992, and one SPB star, Oo 893. The first two stars are monoperiodic pulsators with periods of 0.1716946 and 0.1326359 d respectively, and semi-amplitudes smaller than 0.01 mag. The light curve of Oo 893 can be described by a single 1.193633-day period, slightly non-sinusoidal in shape, and having semi-amplitudes from 19 mmag in [FORMULA] to 48 mmag in U. Oo 893 is the first SPB star found in h and [FORMULA] Persei.

In addition, we discovered seven other variables, including three eclipsing binaries and one [FORMULA] Eri star. One of the binaries is a W UMa-type star and a likely cluster member.

We also present new UBV photometry for 258 stars in the field. The average reddening, estimated from the cluster colour-colour diagram, amounts to [FORMULA] = 0.52 mag. A 0.1 mag dispersion of reddenings within the cluster is also seen.

Key words: stars: binaries: eclipsing – stars: oscillations – stars: variables: general – Galaxy: open clusters and associations: individual: NGC 869 = h Per

Send offprint requests to: A. Pigulski

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© European Southern Observatory (ESO) 1999

Online publication: April 19, 1999