[vsnet-chat 36] Re: SU UMa's and TOADs

[Erik Kuulkers <e.kuulkers1@physics.oxford.ac.uk>]

Taichi Kato wrote:
>    It's rather new to me since I have been taught TOADs are defined by
> their amplitudes -- others like the outburst behavior or the SU UMa-nature
> are frequently met characterstics of this group, and not a part of the
> definition.  Or is the term "TOAD" a synonym for the long-used "WZ Sge star"?

TOADs can be indeed connected to the WZ Sge class of stars.
Although not appreciated by some people, the term TOAD was introduced 
also because WZ Sge is not a very good representative of its class.
Only during one of its outbursts it showed a dip in the outburst light curve 
after a long main superoutburst and a subsequent rebrightening ala AL Com.
The other two outbursts didn't show evidence for such dips in brightness.

> > The bright superoutburst and subsequent rebrightenings in V1028 Cyg      
> > occurred after a long quiescent period and may in this respect resemble  
> > TOADs. However, this star also show periods of regular normal and        
> > superoutburst behaviour.                                                 
> 
>    The outburst pattern of V1028 Cyg does not seem to be so regular.
> Intervals between superoutbursts ranged between one and three years
> -- quite similar to SW UMa as Kuulkers already pointed out.

I meant more regular normal and superoutburst behaviour with respect to 
the TOADs. TOADs such as Al Com and UZ Boo do not seem to show any
normal outbursts. V1028 Cyg and SW UMa superoutburst more often than the 
latter and also show normal outbursts, not connected to the superoutbursts.

>    I generally agree in this point.  There seems to be a continuous transition
> between "classcal" SU UMa stars and WZ Sge stars (or TOADs, if I understand
> the definition correctly) in many points, but the existence of "early" or
> "orbital" superhumps and the apparent lack of triggering normal outbursts
> seem to be unique to the latter extreme end.

Indeed, the presence of "early" or "orbital" superhumps may be another 
criterium for being a TOAD.

Erik Kuulkers

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