(cba:news) CP Puppis, rest in peace (not)

Joe Patterson jop at astro.columbia.edu
Mon Feb 13 09:32:45 EST 2017


Oh... and a big shout-out to the stars of the campaign - Berto, Gordon, 
Josch, and Peter Nelson!

On 2/13/2017 9:26 AM, Joe Patterson wrote:
> Hi CBAers,
>
> I've completed analysis of the CP Pup data for the season.  As was
> hinted at but not quite proved 3 years ago, the photometric period
> really is well separated - about 8% - from the spectroscopic (presumed
> orbital) period.  Hallelujah.  The instability in waveform and period
> shows that it cannot reside in the dynamcal parts of the binary (the
> two stars), but must reside in the disk - the main source of light.
> Your basic superhump.  Ever hear of such things?
>
> Me too.  But 8% separation - not 2% as we thought 20 years ago, based on
> a 1-day alias - breaks all, or almost all, the rules.  It indicates a
> very strong perturbation on the disk by the secondary.  The most
> plausible way to get this is origin at the 2:1 resonance in the disk,
> not 3:1 as is customary for superhumpers.  But very few disks are *big*
> enough to reach the 2:1 resonance; only for a very extreme mass ratio
> (probably M2/M1 less than around 0.05) can the disk extend that far.
> This probably indicates a secondary less than around 0.05 Mo.
>
> Kinda fascinating.  There are very few classical novae of short Porb,
> although the great majority of CVs are of short Porb.  This has always
> been troubling (to me; some others are strangely unruffled by it).  CP
> Pup may guide us to a solution.
>
> But we're done for the year!
>
> joe
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