(cba:news) bt mon eclipses, and classical novae in general

Joe Patterson jop at astro.columbia.edu
Tue Nov 14 08:49:50 EST 2017

Enrique, David Cejudo, and Donn Starkey have obtained time series on BT 
Mon.  The eclipses are now occurring at the end of the "night" (meaning 
observable interval in darkness) in Europe, and at the beginning of the 
night in the USA.  Since the period slightly exceeds 0.33333333 d, the 
eclipses will creep later and later, and hence become good targets for 
observers at USA longitudes.  Not so good for Europe, generally.

HOWEVER... while eclipses are the prime motivator, we're interested in 
the whole orbital light curve. Based on this first look, it seems to 
have more bumps and features than past studies have shown.  So consider 
it a good target at other times.

And, on a grander scale...

The  orbital light curves of old novae are very poorly understood. 
Actually, probably not understood at all.  The published studies are 
star-by-star, one to a customer, and usually based on 1-2 high-speed 
light curves.  But erratic flickering is always present, so orbital 
features other than a deep eclipse are never clear from these studies. 
It's easy for us, since we cover many orbital cycles - maybe 50 or more 
(so flickering is smoothed over).

Also, these light curves ought to CHANGE as the cooling of the WD 
proceeds.  So one ought to study the light curves every few years.  It's 
not as simple as just "outburst" and "quiescence".

The *general* trend seems to be: not much variability within 3-4 mag of 
peak, then a small-but-growing amplitude signal emerges.  That's what T 
Pyx showed (see out recent paper), and some others (V1494 Aql, which 
we're studying thoroughly for these effects).  Select some seasonally- 
and magnitude-appropriate old novae, and see what you get.

My favorites this season are V Per and QZ Aur - both eclipsers, but both 
quite faint.  But plenty of other good ones out there (DN Gem and DM Gem 
are candidates; T Aur isn't - but only because we've just finished that 
study, thanks to Shawn, Tonny, and Jim Boardman).  Beautiful result!

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