A&A 384, 195-205 (2002)
DOI: 10.1051/0004-6361:20011820
Pulsations and orbital modulation of the intermediate polar 1WGA J1958.2+3232
A. J. Norton1, H. Quaintrell1, S. Katajainen2, H. J. Lehto2, K. Mukai3 and I. Negueruela41 Department of Physics and Astronomy, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
e-mail: A.J.Norton@open.ac.uk; H.Quaintrell@open.ac.uk
2 Tuorla Observatory, Turku University, Väisäläntie 20, 21500 Piikkiö, Finland
e-mail: sekataja@astro.utu.fi; hlehto@astro.utu.fi
3 NASA Goddard Space Flight Center, Laboratory for High Energy Astrophysics, Code 662, Greenbelt, MD 20771, USA and Universities Space Research Association
e-mail: mukai@milkyway.gsfc.nasa.gov
4 Observatoire Astronomique de Strasbourg, 11 rue de l'Université, 67000 Strasbourg, France
e-mail: ignacio@isaac.u-strasbg.fr
(Received 20 November 2001 / Accepted 20 December 2001 )
Abstract
We present optical photometry, spectroscopy and photopolarimetry, as
well as ASCA X-ray observations, of the recently discovered intermediate
polar 1WGA J1958.2+3232. Through the first detection of an optical beat
frequency, we confirm the previously tentative suggestion that the spin period
of the white dwarf is twice the X-ray and optical pulsation period, which we
also confirm in each case. We detect an orbital modulation in each of the
U,
B,
V,
R and
I bands for the first time, and suggest that the true orbital period is the
-1d alias of that previously suggested. We also confirm the presence of
circular polarization in this system, detecting a variable polarization which
has opposite signs in each of the
B and
R bands. The double peaked pulse
profile and oppositely signed polarization pulses suggest that 1WGA
J1958.2+3232 accretes onto both magnetic poles via a disc which is truncated
relatively close to the white dwarf.
Key words: novae, cataclysmic variables -- stars: magnetic fields -- stars: individual -- 1WGA J1958.2+3232
Offprint request: A. J. Norton, A.J.Norton@open.ac.uk
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