BZ UMa: Short-term Variations on Rapid Fading
As reported by E. Muyllaert, the unusual dwarf nova BZ UMa experienced its
relatively rare outburst (the last confirmed one in 2001 May). This object
is reported to have a short orbital period (below the period gap), which
may imply the SU UMa-type nature. However, no definite superoutbursts have
been observed. The object may be related to another below-the-gap object
HT Cam, which is confirmed to be an intermediate polar (IP). Although no
definite pulse period had been established, BZ UMa had been reported to
show quasi-periodic oscillations (QPOs) in outburst, which may related to
optical pulses seen in HT Cam (vsnet-campaign-dn
3151, 3152).
Hump Profile
T. Vanmunster performed time-series photometry for 5.05 hr on December 19/20,
and reported that the light curve was rather flat (vsnet-campaign-dn
3160, 3161).
The object was rapidly fading from the outburst on December 22. Superimposed
on this fading, the Okayama team detected modulations with a period close
to 0.066 d. This period looks like to be associated with the orbital period.
Short-period quasi-periodic oscillations with variable amplitudes were also
observed. The strongest period was around 0.023 d. The overall light curve
on Dec. 22 generally resembles that of HT Cam, despite the lack of an acceleration
of the fading rate during the latest stage (vsnet-campaign-dn
3184, 3175).
On Dec. 23 and 24, the object showed large-amplitude (up to 0.8 mag) variations.
At least some of the major peaks seem to have a periodicity close to the
orbital period. Other shorter period oscillations were also present (vsnet-campaign-dn
3194). On Dec. 25, strong and highly coherent variations still appeared.
T. Kato reported that the best-determined period is 0.0657(7) d, which is
slightly shorter than the orbital period (vsnet-campaign-dn
3209).
Links:
Hump profile:
/vsnet/ftpfile/DNe/BZ_UMa/bzph1.gif
[vsnet-campaign-dn
3209]