Dear Dr. Kato, As you know, the standard model for a classical nova is a white dwarf and a red dwarf. I believe that this model has been confirmed by the numerous observations. Various methods of mass determinations are consistent with this model. I'm a bit worried by novae in which a systematic search for variability has been failed (e.g. HR Del, RW UMi, HR Lyr, DM Dem...). There are a few possible explanations for this behaviour (e.g. long periods, noise, strong winds...), but they might constitute a new class of novae with a different binary configuration (e.g. a primary neutron star). Apropos recurrent novae, I'm not an expert in this field, but I think that you can count them as 'novae' with multiple recorded explosions. Classifications are elusive. There are always border cases, and systems usually don't obey all rules of thumbs. It's a matter of terminology. Anyway, recurrent novae are not 'classical' novae. Regards, Alon Retter ------------------------------------------------------------------------- On Fri, 20 Aug 1999, Taichi Kato wrote: > Re: [vsnet-chat 2238] Re: (fwd) Nova Paper research > > > PU Vulpeculae is a symbiotic nova with a period of ~13 years! > > This means a different binary configuration than in classical > > novae, so despite the thermonuclear runaway, exclusion from > > the nova list is justified. > > Several questions: > > 1) What seperates novae from non-novae? Does binary configuration play > an essential part? > > 2) Has binary configuration of "justified novae" been confirmed anyway? > > 3) Recurrent novae have a broad spectrum in the sense of the binary > structure. Aren't they considered as "novae" with mutiple recorded > explosions? > > Regards, > Taichi Kato > >