[vsnet-chat 33] SU UMa's and TOADs

[Taichi Kato <tkato>]

Eric Kuulkers wrote:
> Defining a SU UMa star as a TOAD (or, equivalently, a WZ Sge star) SOLELY
> basing it on outburst magnitude is not the right way to classify it as a 
> TOAD. In addition the star should exhibit long intervals between         
> superoutbursts (years to decades) with almost no normal outbursts.       

   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"?

> 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.

> V1028 Cyg, and a similar system, SW UMa, may be the bridge between       
> normal SU UMa's and TOADs.                                               

   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.

Regards,
Taichi Kato

VSNET Home Page

Return to Daisaku Nogami

---

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