Grazing Eclipsing Dwarf Nova CW Monocerotis: Dwarf Nova-Type Outburst in a Possible Intermediate Polar?

Astrophysics, abstract
astro-ph/0301347

From: Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>

Date: Fri, 17 Jan 2003 08:28:02 GMT   (211kb)

Authors:
T. Kato,
M. Uemura (Kyoto U),
S. Kiyota (VSOLJ),
K. Tanabe,
M. Koizumi,
M. Kida,
Y. Nishi,
S. Tanaka,
R. Ueoka,
H. Yasui (Okayama U Sci.),
T. Vanmunster (Center for Backyard Astrophysics, Belgium),
D. Nogami (Kyoto U),
H. Yamaoka (Kyushu U)

Comments: 11 pages, 11 figures, to appear in PASJ

We observed the 2002 October-November outburst of the dwarf nova CW Mon. The
outburst showed a clear signature of a premaximum halt, and a more rapid
decline after reaching the outburst maximum. On two separate occasions, during
the premaximum stage and near the outburst maximum, shallow eclipses were
recorded. This finding confirms the previously suggested possibility of the
grazing eclipsing nature of this system. The separate occurrence of the
eclipses and the premaximum halt can be understood as a result of a combination
of two-step ignition of an outburst and the inside-out propagation of the
heating wave. We detected a coherent short-period (0.02549 d) signal on two
subsequent nights around the optical maximum. This signal was likely present
during the maximum phase of the 2000 January outburst. We interpret this signal
as a signature of the intermediate polar (IP) type pulses. The rather strange
outburst properties, strong and hard X-ray emission, and the low luminosity of
the outburst maximum might be understood as consequences of the supposed IP
nature. The ratio between the suggested spin period and the orbital period,
however, is rather unusual for a system having an orbital period of ~0.176 d.

References and citations for this submission:

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