(cba:news) v1101 aquilae!

Joe Patterson jop at astro.columbia.edu
Sat Aug 3 12:43:46 EDT 2013


Hi CBAers,

   I've finished my preliminary look at the V1101 Aql data, over the 
first 18 days.  Superb... and in ways that we probably don't yet 
understand.  This star is occasionally classified as a Z Cam star; it 
has some ups, downs, and long in-betweens... so it comes by that label 
honestly.  It's also sometimes compared to RZ LMi, the most frantic of 
the ER UMa stars; that's warranted too, because there's a 20ish-day 
cycle (between high and low states)that recurs.  That's the first oddity 
- because these labels belong to different sides of the period gap. 
It's a Greek among the Trojans.

And it gets much stranger, because the star also appears to show *four* 
other periods: at 3.90 hr, 4.13 hr, 4.73 hr, and 3.0 d.  At least the 
first two are very stable.  For those of you who followed last year's 
adventures, that was the pattern of BK Lyn, the 
nova-turned-novalike-turned-dwarf-nova.  A virtually identical pattern 
in a star longward of the period gap is a really big surprise.

The star ranges from ~15.7 to 14.2 in a 20-day cycle, and shows big 
waves ("negative superehumps" in the jargon of the day) near minimum. 
The variations near maximum are harder to trace, because it looks like 
negative and positive superhumps then superpose.  Another complicating 
factor is that the negative and positive superhumps appear to differ in 
frequency by ~1.10 c/day - creating problems in disentangling 'em.

So far, most of the water is being carried by Joe U and David Cejudo. 
It would be great if more CBAers made this their regular target... and 
if we could remedy our "Pacific gap".  Jim Jones to Jennie McCormick tro 
Bob Rea to Greg Bolt - those would be good handoffs which span the 
entire Pacific (presently our main zone of ignorance).  The daily alias 
issues are especially important near maximum light in the 20-day cycle, 
when the two superhumps seem to wrestle for control of the light.

As a comparison we're mainly using the AAVSO 13.6 star, which has 
V=13.603.  I recommend that one.  Another possibility is the AAVSO 14.9 
star, which has V=14.866.  Most people are using clear filters, with 
cycle times around 1-1.5 min.

The periods are longer... but other than that, this star produces some 
of the most beautiful light curves in our arsenal!

joe p

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