[vsnet-chat 356] Last-Chance Saloon of CVs

[Joe Patterson <jop@astro.columbia.edu>]

Great note from Taichi re V844 Her [vsnet-alert 940].  What wonderful
things we may learn from this mysterious short-period regime!

I did want to be a contrarian about all these dwarf-nova classes, though.
People talk about ER UMa stars, SU UMa stars, WZ Sge stars,
"transition objects" between the SUs and the WZs, and it is only by good
fortune that no one has yet noticed (or noticed in print) that there are
transition objects between the ERs and the SUs.  Namely, HS Vir, V503 Cyg,
YZ Cnc.  Whenever I ponder this collection ranging from the frenetic 
RZ LMi to the sluggish WZ Sge, I'm struck with how similar the stars
are, despite the enormous dispersion in activity.  And plotting the
observable quantities against each other, I basically find a continuum -
no impressive evidence for clustering.

So I tend to think that we've been subjecting these dwarf novae to an
excessive Balkanization.  "SU UMa stars" is good enough for practically
all purposes.             

Now these many terms are fine for discussion among experts, since 
they summarize observable (but not necessarily deep) differences.  To
me they're still just a shorthand, not yet demonstrably indicative of
significant difference in underlying physics.  
          
Looked at in sufficient detail, any class will show some differences. 
There will be correlations too.  Tall people tend to play basketball.  
Short people tend to work on submarines.                                 


Joe Patterson
CBA-New York

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