Search for forced oscillations in binaries^*

IV. The eclipsing binary V436 Per revisited

¹ Institute of Theoretical Physics and Astrophysics, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic
² Astronomical Institute of the Charles University, V Holešovičkách 2, 180 00 Praha 8, Czech Republic
³ Astronomical Institute, Academy of Sciences of the Czech Republic, 251 65 Ondřejov, Czech Republic e-mail: hec(had)@sunstel.asu.cas.cz
⁴ Thüringer Landessternwarte Tautenburg, 07778 Tautenburg, Germany e-mail: lehm@tls-tautenburg.de
⁵ Dept. of Physics and Astronomy, University of Victoria, PO Box 3055, Victoria BC V8W 3P6, Canada e-mail: yang@beluga.phys.uvic.ca
⁶ Hvar Observatory, Faculty of Geodesy, Zagreb University, Kačićeva 26, 10000 Zagreb, Croatia e-mail: hbozic(rdomagoj,dsudar)@geodet.geof.hr
⁷ Ankara University, Science Faculty, Astronomy and Space Science Dept., Tandoğan, Ankara 06100, Turkey e-mail: ak@astro1.science.ankara.edu.tr
⁸ Departamento de Astronomia, Universidad de Guanajuato, Apartado 144, 36000 Guanajuato, GTO, Mexico e-mail: eenens@astro.ugto.mx
⁹ National Optical Astronomy Observatories, PO Box 26732, 950 N. Cherry Ave., Tucson, AZ 85726-6732, USA e-mail: hubeny@noao.edu
¹⁰ Department of Physics and Astronomy, Michigan State University, E. Lansing, MI, 48824 and Visiting Scholar, Department of Astronomy, University of Washington, Seattle, WA 98195, USA e-mail: linnell@astro.washington.edu

Corresponding author: J. Janík, honza@physics.muni.cz

Received: 24 March 2003
Accepted: 27 May 2003

Abstract

An analysis of new spectroscopic and photoelectric observations, satisfactorily covering the whole orbital period of V436 Per, together with existing data allowed us to improve the knowledge of the basic physical characteristics of the binary and its components. In several aspects, our new results differ from the findings of Paper I of this series: in particular, we found that it is the star eclipsed in the secondary minimum which is slightly more massive and larger than the optical primary. We also conclude that the apsidal advance – if present at all – is much slower than that estimated in a previous study. The orbital period might be increasing by 0.28 s per year but also this finding is very uncertain and needs verification by future observations. It is encouraging to note that two completely independent sets of programs for light-curve solutions lead to identical results. A notable finding is that both binary components rotate with very similar – if not identical – rotational periods of 145 and 140, much shorter than what would correspond to a 109 spin-orbit synchronization period at periastron. Rapid line-profile changes reported earlier could not be confirmed from new, dedicated series of high-resolution and S/N spectra.