(cba:news) v1674 Her: a lesson in speed
jop at astro.columbia.edu
Tue Sep 7 11:32:59 EDT 2021
I've been spending a few weeks studying the periodic signals of thiis
ultrafast nova - Herculean in speed as well as sky location. It's
remarkably willing to cough up its secrets to time-series photometry.
There are two stable signals in the light curve, at 3.67 hours and 8.36
minutes. At or near quiescence, no big deal; we've seen a few of these
before in novae. But I thought it remarkable that this behavior
occurred 4-8 magnitudes above quiescence. We'll need to really lean on
the physics to understand THAT.
I didn't spend much time on the earliest phases, because our data is
pretty sparse; the nova is so fast, and it takes a while to get a
But I finally got around to studying those first ten days of outburst.
The nova flashed on June 12, and our coverage starts June 15. The first
three days included data from Tonny (of course), Ken Menzies, and
Michael Richmond. I was astounded to see a very large amplitude signal
seemingly in agreement with the 3.67 hr period, but definitely 180
degrees out of phase with it.
Very provocative. In the following ten weeks the star settled down to a
waveform reminiscent of T Pyx and many (maybe all) supersofts. In the
remaining 6 weeks of the observing season, let's keep up the pressure
and be at the ready for any more surprises. And I'll probably be
checking for factors of -1 practically every day.
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