(cba:news) early may stellar menu
jop at astro.columbia.edu
Tue May 6 22:12:59 EDT 2014
The month of AY Sex has come to an end. The HST spectroscopic
observation (basically a time-resolved 1100-3000 A spectrum) was
beautiful and a humdinger - looked practically like a quasar spectrum
(numerous very broad and generally high-excitation lines... and a few
weak mystery lines). Thanks for all the coverage!
Also time to ring the curtain down on DW UMa and OT1759+25. It
would, however, be good to continue observations of T Pyx, HP Lib, and
perhaps AM CVn. These are not quite ripe yet in their 2014 coverage.
May-June-July is high season for classical novae, and let's go get
'em. I've become ever more fascinated by their orbital light curves
over the few decades after eruption. Early in the decay, the light
curves look like classic reflection effects, as if the secondary is
merely reflecting the incident light from the hot white dwarf ("heating
effect"). Then it can acts as a bolometer for the white dwarf, long
after the supersoft X-ray source has disappeared. We've tested this out
for one nova, and managed to follow T_wd down to 120,000 K. That was a
thrill for me; the X-ray telescopes can't detect anything south of
300,000 K. Later on, it seems to get more complex... but anyway, the
point is to obtain orbital light curves season by season. Within the
first 5-10 years, the changes are most obvious - presumably since the
white dwarf cools faster then. We've started similar programs on NR
TrA, V1494 Aql, V339 Del, V959 Mon, V2491 Cyg, V382 Vel, V2362 Cyg, and
V1500 Cyg. Some of these are off-season, but bear 'em in mind. Also,
smapshot estimates of magnitude will be very helpful too. These stars
are pretty neglected years after outburst... so we often don't know
whether they're feasible targets (until you look).
Also, the most recent novae (2013-4) are of great interest too -
we'd like to know exactly when the orbital wave first appears. This is
probably the exact time the ejected shell goes transparent - out first
look at the underlying hot white dwarf. By comparing that to the time
the soft X-rays first appear, as seen by the SWIFT satellite, we'll get
our theory tested.
While we're on the subject of heating, there's *dwarf* novae to
think about too. V355 UMa and GW Lib are both WZ Sge - type dwarf novae
which had recent outbursts, and both contain pulsating white dwarfs as
well. Still well placed in the sky, but somewhat challenging for
For very lengthy runs on northern stars, my #1 recommendation is HS
1813+6122 (J2000: 18 14 29.83 +61 23 34.3) = "Dra" in Downes catalog.
Decently bright star, very very likely to show superhumps. And it's
time also to do a campaign on UX UMa, which we have criminally avoided
all these years. Perfectly placed in the night sky.
Scrambling to get my SAS/AAVSO paper in. It's wonderful that so
many of you are coming this year.
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