(cba:news) UZ Boo, V1101 Aql, mainly
jop at astro.columbia.edu
Fri Jul 26 07:09:57 EDT 2013
UZ Boo is in outburst again, about 10 years after the last. We've only
seen two previous outbursts, both very sparsely observed. This is a
dwarf nova with our favorite credentials: nearby (~150 pc), WZ Sge
class, relatively long period. Beautiful! Despite the inconvenience of
Bootes in late July, this is still an extremely desirable target. With
decent weather and a Europe-eastern Americas-western Americas handoff,
we stand a pretty good chance of deciphering the period structure.
What's happening in Aquila these days? Well, for us, anyway. First,
we're finished with V1315 Aql. Nice eclipses, but a weak superhump this
year, and we're done with it. The V1432 Aql campaign is going well, but
only needs occasional coverage - once a week is just fine. The star I
strongly recommend for intensive coverage is V1101 Aquilae, which is
busy flashing a beautiful smile full of negative superhumps.
Technically I suppose it's "the first Z Cam star to show superhumps" -
though that's a somewhat weak statement, since Z Cam is really not a
well-defined moniker, and they're hardly ever studied in long nightly
time series. Anyway, there are a host of unanswered questions: how long
will they last? how stable are they? are there also positive
superhumps? is there also a superorbital ("nodal precession") frequency
present? At 14.4, everyone can do this star, and I hope some AU-NZ
observers will take a crack at it too, since we usually lack
observations from Australasia. And be sure to specify comparison star;
studies for the superorbital period (supposedly around 4 days) will
require a close calibration between observing stations.
The two main southern stars I'm promoting now are GW Lib and BW Scl.
Both recent erupters which have shown WD pulsations, as well as some
mysterious long-period signals - origin still unknown. Decently placed
in the sky, and bright enough for average, roughly clear nights (~16.5).
I'll repeat a wish list, though: V4743 Sgr, V1494 Aql, IM Nor, V4633
Sgr, V3890 Sgr (in order of increasing faintness and/or difficulty).
Faintness or crowded fields guard these stars' secrets quite well, but
there are suspicions that those secrets are worth knowing!
The X-ray variable in Equuleus. Enrique, Josch, and Jim Jones are
covering this guy pretty well, and it's variable on MANY timescales.
But so far, no period. Disappointing. Yet the spectrum and extreme
variability definitely suggest some kind of high-Mdot CV. At 12th
magnitude, good target for small scopes. Let's keep going another 1-2
weeks at least. It might be a good idea to try for a very fast cycle
time (10 s?) - so far we haven't investigated that regime.
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