(cba:news) stars for october

Joe Patterson jop at astro.columbia.edu
Mon Oct 10 17:44:16 EDT 2016


Hi CBAers,

Here's a good menu for October nights.  Plain-text file. I might have 
forgotten an important star, so feel free to ask!  Also, I hope to see 
some of you in Boston next month (AAVSO).

joe p
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                                                        October 10, 2016.
Dear CBAers,

New month, new stars.

As some of you know, Enrique spent the summer in New York, and we scrambled
to get some of our projects concluded while we had that opportunity.  We
had a few single-star successes (ES Cet, RX2133+51, IM Nor; and CD Ind from
Gordon Myers)... but the most amazing accomplishment, to me, was his
successful phase-up of the "spin pulses" of 8-10 DQ Her stars.  The period
changes in these stars have always been puzzling.  Some are spinning up,
some are spinning down, some are doing both (not simultaneously!).  I've
always been pessimistic that I would ever solve this problem, but kept
the campaigns going year after year, since we're the only people able
and willing to do it.  I thought we were basically stockpiling data for
someone *else* to figure it out many years from now.
                                                 
But Enrique solved it this summer.  He found, basically, that you can
measure accretion rate by measuring the spin-up rates.  The DQs with Porb
exceeding 3 hours show 10**-8 Mo/yr, and those with Porb<2.5 hours show
10**-10 Mo/yr.  So far, no exceptions!

Of course we'll keep these campaigns going.  Once you have established the
cycle count over many years, the amount of coverage needed to extend it is
pretty small.

And so, STARS FOR OCTOBER:

V704 And.  We need a few weeks of very extensive coverage.  Long as possible,
as frequent as possible for a few weeks.

RX And.  Many-telescope campaign going on now from space.  Let's support it
as best we can.

V592 Cas.  Bright, perfectly placed in the northern sky, and a star that
has so far concealed its secrets from us.  FS Aur: same story.

ES Cet.  The star is faint and with a very fast period (10 minutes).  But    
let's get a few more timings on it before completing our study.

Each of these stars calls for a "campaign" - an intensive series of nightly
observations.  Others are somewhat more speculative; we need to look at a
few runs and see how promising is the star.  Some are pretty faint, too;
I *think* we can get good data on them, but it remains to be proven.

T Pyx (just coming out in the morning sky, I hope).  If you can get 2 hour
runs, that would be good.  Longer is better, of course.

HZ Pup, also just coming out in the morning, maybe.  If not now, then as
soon as you can manage 2 hour runs on it.

HV Cet. 19th mag, a stretch - but "high priority" if you can manage it.

V1500 Cyg and V Per.  18th mag, but ex-novae, which have become our favorite
kinds of targets.  Can you get 'em?

That's it.  Enrique, can you advise on PX And?  The coverage looks
amazingly good, but I haven't analyzed the actual data.

joe p


                                                                   
                         
                         
                                      
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