[vsnet-campaign-ip 70] HT Cam: incredible modulations!

[Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>]

HT Cam: incredible modulations!

Dear Colleagues,

    We have further analyzed the Kyoto and RIKEN (Torii-san) data taken
last night.

    The quick-look light curve clearly shows the presence of strong (up to
0.5 mag) long-period waves, which is most likely related to the orbital
(or something like superhumps) period.  The dominating period is close
to 0.063 d, which is longer than the reported orbital period.

    Most strikingly, the light curve during latter half of the night
(analysis still in progress) is dominated by modulations with a period
of ~4 min (!).  The period is close to the half of the reported (8.5 m)
period in quiescence.  If this phenomenon reflects the IP (intermediate
polar) type modulations, this period strongly suggests that two-pole
accretion takes place.  It may be possible that a higher accretion
rate during the outburst phase transiently modified the magnetospheric
structure, enabling two active poles.

    An alternative explanation would be QPOs, as an analogy to QPOs in
X-ray binaries (with magnetized white dwarfs).  Further refinement of
the period and pulse preofile will be able to descriminate these
possibilities.  We are thus very looking forward to receiving any
additional data during this outburst.

    Please send your time-series observations to:

    ishioka@kusastro.kyoto-u.ac.jp
    uemura@kusastro.kyoto-u.ac.jp
    tkato@kusastro.kyoto-u.ac.jp

    in order to minimize the delay in analysis.

Regards,
Taichi Kato
VSNET Collaboration team

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