[vsnet-alert 9272] EX Hya outburst: emergence of strong spin signals etc

[Taichi Kato]

   Berto Monard and Nakajima-san have reported further
observations of EX Hya.  Berto's observation was 1+ d
after Nakajima-san's initial observation.

   During Berto's entire run, the light curve was strongly
modulated by the spin period of the white dwarf, while
this signal was almost absent in Nakajima-san's initial
and most recent (Apr 3) observations.  We have also confirmed
that eclipses during the outburst maximum occurred
systematically earlier.

   The overall data seem to well support the picture that
the outburst started in the outer disk (brightened eclipsed
component), whose matter subsequently accreted onto the
white dwarf, resulting the strong spin signal (cf. the similar
phenomenon was recorded in HT Cam, Ishioka et al. 2002
PASJ 54, 581; see also MNRAS 313, 703 by Hellier et al. 2000
discussing on the 1998 outburst of EX Hya).