(cba:news) stars for august
jop at astro.columbia.edu
Fri Jul 30 17:05:46 EDT 2010
That "AM/DN" star in Centaurus has stirred up some fuss. A quite
fascinating spectrum is getting passed around; it shows very, very high
excitation, proving that the star is still a very intense source of soft
X-rays. And that's consistent with the X-ray results too (although
there is currently no X-ray telescope sensitive to *very* soft X-rays,
the X-ray spectrum basically corroborates this). I say "still" because
the star first erupted a long time ago, I believe greater than a year.
It's very, very desirable (hey, I'm begging) to obtain an orbital light
curve before Centaurus disappears completely into the western twilight.
Chris Stockdale (AU) has obtained 3 nights, and Berto one short one.
I'm hoping that combining AU/NZ data (basically Auckland to Perth) with
ZA data will clinch the period solution. It's a big variation, I think
about 13.8 to 14.5... and Chris's data suggests a period around 5 hours
(but aliased - single-observer data will certainly be aliased this time
BTW the star is at 11 51 13.06
-62 37 29
For northern objects, scratch V1315 Aql and V603 Aql. The coverage was
good, but basically verified that the stars are up to their usual tricks
- negative and positive superhumps, respectively. I'll bundle the new
data in with the old... but not much promise of novelty this year.
HS1813+61 looks more promising. This year's campaign is nowhere near as
thorough as 5 years ago (we're not getting the looonnng nightly runs),
but it does look like the star is *probably* sprouting negative and
positive suoerhumps simultaneously. That's well worth exploring - so
leave it on the list.
The northern object I'd like to promote most heavily is WZ Sge. It's
now 9 years since the last eruption. We have *never* - nor has anyone
else - had a concerted campaign at quiescence, and everything you learn
about WZ Sge pays off quadruply, because there is so much else known
(including a very precise distance). It's definitely Sagitta season,
and at V=15 it's a reasonably easy target for most CBAers on decent
nights (but watch out for the intruder star 12 arcsec away).
Then there's the DQ Hers, nice targets for tracking period changes. A
short run (2 hr or so) usually does the trick, though longer is always
better. I'm hoping to include 2010 data in an omnibus DQ Her paper at
year's end. Here are the guys:
IGR 0023+61 (Cas)
Thanks, and happy observing!
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