[vsnet-alert 1404] CR Boo rapidly fading

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

CR Boo rapidly fading

   CCD observations at Ouda Station has shown CR Boo is fading at a rate of
0.1mag/hour.  A prerlimnary magnitude on Jan. 2.803 was V=14.88.  Available
data suggest outbursts of CR Boo in this phase are short-lived, bearing
all characteristic of normal outbursts.  Apart from slight irregularity,
CR Boo has all the charateristics of hydrogen-counterpart of extreme SU UMa-
type dwarf novae, ER UMa stars.  Superoutbursts of CR Boo last typically
15-25 d, short, normal, outburst having amplitudes of 2-2.5 mag, with a
recurrence time of ~4 d, typical supercycle of 40-45 d, and an extremely
large duty cycle (40-50%) of superoutburst.  These finding seems to support
the theoretical model by Tsugawa (1997), an application of thermal-tidal
instability models to a high mass-transfer helium disk.

   Observers are strongly encouraged to include this brightest helium
dwarf nova as the top priority nightly targets as well as 'classical'
ER UMa stars.

Regards,
Taichi Kato

VSNET Home Page

Return to Daisaku Nogami

---

vsnet-adm@kusastro.kyoto-u.ac.jp