(cba:news) January stars

Joe Patterson jop at astro.columbia.edu
Fri Jan 19 14:26:03 EST 2001

Dear CBAers,

Well, I think I am finally recovered from my seizures in Taiwan.
Without Jonathan's help I'd be struggling to get out of the country
(and maybe even the hotel), but now I've managed to give two classes
and can even remember the names of all these CVs.  Ten days ago I
didn't know my own name.  Redundant storage, what a great idea that

We - Jonathan and two trainees - start an observing run tonight at Kitt
Peak.  The top priority is RZ LMI AT QUIESCENCE.  RZ LMi is perhaps the
most active of all the hydrogen-rich dwarf novae, and it's debatable
whether it ever even reaches quiescence.  Anyway, it does sometimes slink
down to 17th mag, which is about the right ballpark.  The main point is to
track the peroperties of the superhumps through say two complete cycles of
supermax, max, quiescence.  When we tried this six years ago, we found
something pretty amazing: the superhumps really never went away, and
didn't lose coherence either.  They seemed actually to maintain coherence
over 5 consecutive supermaxima.  I couldn't prove it though; superhumps
are always a little slippery, and it will take more persistent coverage to
prove or disprove the case.

We assign high priority to RZ LMi at other phases of the outburst
cycle too, since otherwise there can be no chance of tracking the star
continuously.  Superoutburst, especially, should be very interesting
since the signal is strong and we should learn many of the finer details
about the superhump (quasi-harmonics etc.).  

The other northern target is BH Lyn, an eclipsing SW Sex star which has
shown both positive and negative superhumps in past years.  Except in
eclipse, this star is always about 14.7, so it's one that just about
everyone can do.  It's time to get one more intense 3-week look at the
star, and then publish the results.

In the south, Robert Rea and Maria Marsh have been waging a heroic
campaign on TW Pic from New Zealand.  The case for a 10-hour period looks
pretty good, and Brian Warner tells me they have several nights from
South Africa which should break the aliases.  However, it is perhaps the
strangest looking power spectrum I ever saw, and one of the strangest
light curves - up/down episodes of 1 magnitude which last <2 hours.  I
can't figure this guy out yet, it just doesn't fit pre-existing boxes.
We should continue for at least another week, then re-evaluate.

Finally, there's T Pyx, back in the midnight sky.  This is the galaxy's
only short-period CV of very high luminosity, and previous evidence
suggests the 1.8 hr binary period is changing rapidly.  A couple weeks
of coverage now, and then again 8-10 weeks later, will give us two lovely
new points to plunk on the O-C curve.  Won't you help us generate such
lovely points?


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