(cba:news) ER UMa, SDSS1339, CP Pup, BK Lyn, DW UMa

Joe Patterson jop at astro.columbia.edu
Wed Mar 2 17:28:03 EST 2011

Dear CBAers,

Wow, what a bunch of stars in February.  ER UMa and SDSS1339+48 continue 
to light up our sky with beautiful periodic variations!  The signals in 
ER UMa must surely tell us a lot, because they are large-amplitude in a 
bright star, and very phase-stable.  Just ideal for the long term study 
that has never been feasible in any other star - because the signal 
vanishes, the star vanishes, or the stability is too low to follow 
definitively.  Keep the faith on through the next superoutburst, and a 
little beyond - i.e. at least 3 more weeks.

SDSS1339+48 still hasn't shown its hand, just recently dropping down to 
V=15.  Will it show echoes?  Will the humps stay around for months like 
WZ Sge/GW Lib?  Will the periodic WD pulsations return soon?  Will the 
unexplained large 7 hr period at quiescence pop back up again?  All 
unknown,  At some level, we're going to want to follow this throughout 
the (northern) spring.  Definitely good for long time series, which as 
usual are much more valuable than the short guys.

And I have to say, at great risk of crying "fire" too often, that CP 
Puppis is even more interesting.  I was SHOCKED by the first few light 
curves of Bob Rea - showing a very strong periodic signal at a period 
considerably shorter than the alleged Porb.  That weird signal is still 
there, but it now appears to be multiperiodic - and it will take a good 
multi-longitude set of time series to unravel it (separate the closely 
spaced components).  Berto and Bob are doing well with it, and some 
observations from the southern USA (Tom K and Shawn Dvorak) have been 
very helpful.  I really hope that Greg Bolt (Perth), or some Aussies, 
can get some suitable runs on it.

More generally, I think 2011 is going to be a breakout year for negative 
superhumps.  For years they have been trying, and mostly failing, to 
break out from my computer.  Now they have to, having been liberated by 
the black magic of ER UMa.

There's so much new stuff, I'm not nearly caught up.  But I have learned 
all that.  My preliminary analysis on BH Lyn is negative - no 
discernible humps (other than the variation-cum-eclipse at Porb).  So 
that's probably done for the year.  The other two (likely) bright stars 
to go after now are BK Lyn and DW UMa - also fine negative-superhump 
specimens that have not been properly published yet.


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