[vsnet-alert 22669] Re: ASASSN-18yi: superhump period

[Taichi Kato]

Re: ASASSN-18yi: superhump period

> The mass ratio estimated from the
> orbital period and superhump period is 0.338(3) d.

   This estimate also assumes that current superhumps
are of stage A.  It is worth noting that the outburst
started on Oct. 19.  Considering that superhumps were
not yet apparent on Oct. 26, it took 7 days to develop
superhumps.  This delay is almost comparable to
WZ Sge-type dwarf novae.  Outbursts appear to have been
infrequent as judged from the CRTS and ASAS-SN data.
This object, despite that it is above the period gap,
the mass-transfer rate may be as low as in WZ Sge-type
systems and the disk may have reached the tidal truncation
radius during the current outburst due to the large
stored mass in quiescence.  This may explain the flat-top
shape of the outburst (type B outburst in Osaki & Meyer
2003, A&A 401, 325).  The outburst may have lasted
long enough to enable weak tidal instability to develop.
During this outburst, both variation of the superhump
period and the disk radius are very important.
Detailed observations of eclipses (with higher
time resolutions) as well as superhumps are desired.
We may also expect post-superoutburst reberightening(s).