[vsnet-chat 2890] Brief IP outbursts

[Patrick Schmeer <p.schmeer@mx.uni-saarland.de>]

Alon Retter wrote:
> Mini-outbursts have been observed in the past in TV Col (Szkody & Mateo
> 1984; Schwartz et al. 1988; Hellier & Buckley 1993; Augusteijn et al. 
> 1994). They have amplitudes of about 2 mag, and a duration of less than 
> a day. Mini-outbursts have been also detected in other CVs: in the
> intermediate polars V1223~Sgr (van Amerongen & van Paradijs 1989); and 
> EX Hya (e.g. Hellier et al. 1989; see also discussion in Hellier et al.
> 2000); in the intermediate polar candidate RXJ0757.0+6306 (Tovmassian et
> al. 1998; Kato 1999); in AM Her systems (e.g. Warren et al. 1993), and in

Are all intermediate polars candidates for such outbursts? Or can some
systems be ruled out?

I wouldn't call the brightenings of the IP candidate HT Cam (= RX J0757...)
'mini-outbursts'. The outburst that I observed on 1999 May 23 (vsnet-alert
3014, 3025) had an amplitude of more than 4 magnitudes. One day later the  
variable was back at quiescence. Such a rapid fading has never been
observed during normal outbursts of SU UMa-type dwarf novae (outside
eclipses ;-)). However, Taichi Kato commented that on the other hand such 
large-amplitude outbursts had never been observed in intermediate polars
(although I would say that the outburst amplitude of HT Cam is not so much
larger than that of EX Hya). So how can this below-the-orbital-period-gap
system be classified? 
 
I think the intermediate polar DO Dra should also have been included in
Alon's list. Or doesn't he count the brightenings to mag 10 of this variable
as 'mini'-outbursts? They have about the same outburst amplitude as those of
EX Hya and HT Cam (remark: the (bright) outbursts of DO Dra and EX Hya last
longer than one day). 

> They are most likely generated by mass transfer events, and are not
> similar to dwarf nova outbursts. I guess that in every CV this property
> would be found if it will be observed densely enough. 
 
Several years ago Stefan Korth and I observed independently the reverse(?) 
phenomenon. During a standstill (mag about 11.7) the brightness of RX And
dropped for one day by about 1 magnitude. 
 
Regards,
Patrick
 
P.S.:
What kind of observations should be made during IP outbursts? Time-resolved
photometry? Spectroscopy?

VSNET Home Page

Return to Daisaku Nogami

---

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