[vsnet-alert 12935] ER UMa: superoutburst, final rise and negative superhumps

[Taichi Kato]

ER UMa: superoutburst, final rise and negative superhumps

   As noted by Enrique de Miguel, the final rise to the present superoutburst
took place on March 3.2 UT.  The object brightened by 0.6 mag within
one superhump cycle.  The amplitudes of negative superhumps decreased
following this final rise.

   Even after this, there has been no major phase shift in negative
superhumps, and the phenomenon appears to have been continuous.
The mean period since the start of the present outburst has been
0.06217(2) d, slightly shorter than the period obtained during
the Jan.-Feb. superoutburst.

   The present superoutburst provides a great opportunity how negative
superhumps (or potentially other phenomenon) develops during such
an anomalous condition.  Please also remember ER UMa is renowned
for its unusually large-amplitude superhumps
http://adsabs.harvard.edu/abs/1996PASJ...48L...5K
which appear to be lacking during the present superoutburst.
What makes a difference? -- intensive observations during the current
outburst would provide a clue to understanding the negative superhumps
and ER UMa-type phenomenon!