(cba:news) september stars - a big menu

Joe Patterson jop at astro.columbia.edu
Sat Aug 29 18:40:01 EDT 2015


a plain-text file (I'll send pdf if you can't read it)

joe
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                                                          Aug. 29, 2015.

Hi CBAers,

Very good coverage in recent weeks.  Some of the targets are ready to
retire:

LS Peg. *Great* coverage of this bright and very active star.  Unfortunately
it seems to be reliuctant to cough up any of its secrets to time-series
photometry.  Time to quit, I think.

WZ Sge.  I had great hopes for this star, but the first week's coverage
was not encouraging.  Lots of action - a beautiful light curve, considering
its faintness.  But no new periods.  At most, we'll revive it next year,

And some almost ready to retire:

LQ Peg.  Very impressive light curve, and worth continuing for at least
another week.  Just a single period (2.99 hrs) evident so far, but hints
that some more subtle structure may emerge with more work.

V380 Oph.  Thanks mainly to Gordon and Bill Goff, we now have an
apparently *orbital* light curve of this very faint (19th mag) star.
The orbital period is different from the published period, but the difference
indicates that the published period is an incorrect selection of an
alias (so ours is correct).  The precise value of Porb is of no special
interest, but the shape of the light curve suggests interpretation as
a heating effect - heating of the secondary by the hot white dwarf, with
very little contribution from the accretion disk (if any).  Nice!

Just a few more nights would wrap up our work on these two stars.  For LQ
Peg, it would be best to do that *now*; for V380 Oph, waiting for excellent
observing conditions might be smart.

OLD NOVAE

We're getting great results on old novae, and there are lots in the July-
October time window.

1. QU Vul (N 1984). Still at 15.5, and a short-period eclipser.  Made
to order for CBA coverage!  A top priority target.

2. V1974 Cyg (N 1992, "the nova of the century").  Mag 17.5, and a
harder target.  We need one more season to complete our study - where
"season" could be as little as 7-10 days if we could get *dense* coverage.

3. V630 Sgr (N 1936).  Anothrer short-period guy which has escaped our
attention in the past.  I think qbout 17 (but I dunno).

4. V Per (N 1887).  Another short-period and deep eclipser.  At 18.5,
it's an ambitious target - but is likely to yield big rewards if you 
handle the magnitude


NOVALIKES

1. HV And.  A 15-16 mag star which has been strangely negkected for many
years.  Fred Ringwald has found it to be a new SW Sex star, and those
have become a specialty of ours.  Let's do it.

2. QR And.  An eclipsing supersoft source, apparently with a Porb
rapidly increasing.  We need a few eclipses in 2015.

3. AQ Men.  Somewhat out of season, but at -80 degrees, the season is
really long.  Josch Hambsch is getting steady coverage from Chile.

4. ES Cet.  Need some more runs on this helium star, to test GR as the
driver of mass transfer.

5. CD Ind (an asynchronous polar).  Rapidly oscillating between ~17 and
~19 - pretty wild changes.  The cba-chat messages from Gordon tell the
story.  Not entirely new for this star, but much more extreme than anything
in the record.  Worth continuing!


Lots of targets.  As usual, your observations are likely to have the
most impact if you adopt a favorite star and stick with it.


joe

BTW a remark on comp stars.  It's definitely best if you keep the same
comp star fro all your observations - assuming your original choice is
halfway decent (nothing too red, too crowded, too faint).  This is
especially true if your photometry is unfiltered, because unfiltered
magnitudes can't be put on a standard scale anyway.  If you do change
your comp star, make it obvious in big fluorescent letters.
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