From jop at astro.columbia.edu  Tue Sep  7 11:32:59 2021
From: jop at astro.columbia.edu (Joe Patterson)
Date: Tue, 7 Sep 2021 11:32:59 -0400
Subject: (cba:news) v1674 Her: a lesson in speed
Message-ID: <6a03cca1-2f74-53d1-355e-168e21c2854a@astro.columbia.edu>

Hi CBAers,

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 
campaign going.

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.

joe


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From jop at astro.columbia.edu  Fri Sep 24 12:40:43 2021
From: jop at astro.columbia.edu (Joe Patterson)
Date: Fri, 24 Sep 2021 12:40:43 -0400
Subject: (cba:news) V1674 Her: Save the Last Dance for Me
Message-ID: <65257c19-d5a5-e6a9-2928-eb735eff94e8@astro.columbia.edu>

Hi CBAers,

Hercules is no longer in prime position, but it would be *great* if we 
could get two more weeks of data on Nova Her - especially in the USA 
where the coverage has fallen off.  Aside from being (maybe) the 
fastest/most luminous nova in history, it has shocked me with its two 
periodic signals - orbit and spin.  I think there is good evidence here 
that accretion (not just nuclear) plays a large part in the nova 
energetics. The last I checked, this is nova heresy.

The most recent data is a tad sketchy, largely due to sky position and a 
bright moon.  But it looks like the 3.6 hour orbital wave, really 
healthy for the last 70 days, is now getting weak.  Simultaneously the 
8-minute spin signal appears to be strengthening.  Whether we can prove 
this depends on the density of coverage during the next two weeks

As usual, *length* of run matters a lot.  This time of year, 3 hours 
would be great.  1 hour doesn't help much.  The spin ephemeris is in 
good shape; only the orbit is getting funky.

Got any not-yet-sent runs?  I'm awfully eager to see them!

joe

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