(cba:news) Nova Del 2013, a last hurrah

Joe Patterson jop at astro.columbia.edu
Wed Dec 4 10:46:25 EST 2013


Dear CBAers,

Several recent ATels discuss the strong supersoft source now visible in 
Nova Del 2013 = V339 Del and also the ~56 second periodicity in X-rays. 
  The origin of the supersoft emission has got to be the hot white 
dwarf... and if we can see it basically unobscured, then there's a 
decent chance (far from certain, but a decent chance) that the secondary 
star can also.  And if it does, then we ought to see a periodic 
modulation as the heated face of the secondary wheels around in binary 
orbit.

That's a good reason to REINSTATE V339 Del as a primary target, despite 
the awkwardness of Delphinus in December.  If we can stitch together 
enough longitudes, we can perhaps still cover enough of the day to see a 
periodic signal.

The 56 s period is a different matter.  Its origin is far from clear, 
but because the timescale is so short, it's likely to be *something* 
associated with the white dwarf - which we can now see.  So that's 
another thing to look for, and that search is not particularly hampered 
(slightly, but not that much) by the poor sky position.  You do need a 
total cycle time less than ~20 s to detect this, though.  And if you can 
possibly get that cycle time down ~12 s, you can also cover the 
possibility that most of the power is in the second harmonic (at 28 s. 
Sometimes that happens... but then again, if you're mainly just reading 
out rather than collecting photons, then it's not a good trade-off.

Give it a try.  Each day is another 4 minutes lost!

joe
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