(cba:news) WX Ari, V1101 Aql, FO Aqr, and the two assassins

Joe Patterson jop at astro.columbia.edu
Mon Oct 20 07:22:52 EDT 2014

Hi CBAers,

Great, great coverage on ASASSN-14ei (see Enrique's note in cba-chat). 
7 echo outbursts and counting... and some other 15-hour wiggles that 
resist understanding (no real precedent for such things).  The usual 
southern stalwarts: Gordon, Berto, Josch, Bob Rea... and now I see some 
Peter Nelson data coming in.  Follow this helium CV to the last photon.

And now GAIA, a new arrival to our Solar System, has found another 
helium CV:

Actually this is a re-discovery of ASASSN-14cn, announced back in June 
2014.  But the ATel announcement of the doubled helium lines ratchets 
this guy up in importance.  Very poorly placed in the evening sky.  But 
on the other hand, the period is likely to be very short (<1 hour), so 
there's "bang for your buck".  Let's get acquainted with this guy in 
this last month of its season!

Enrique and Richard Sabo have jumped on WX Ari, a VY Scl star 
("anti-dwarfnova") now in a low state.  As hoped, it has a smooth 
orbital modulation now, possibly due to the heated secondary.  My 
further hope is that we can use this to deduce the temperature of the WD 
(and it wouldn't hurt to have a direct measure of that temperature from 
HST, by the way).  Let's work hard to assemble that orbital light curve. 
  The period is ~3.5 hours, but it's quite faint, so for high precision 
we need to collect many dozens of orbits.

FO Aqr.  Wow, CBAers really jumped on this one!  The light curves are 
beyond beautiful, and demonstrate that the very rapid shortening of the 
period really did happen.  But the point is proven, and we can now 
continue to follow it without intensive coverage.  Keep going, but mark 
it for occasional (weekly?) observations.  At a dec of -8, available to 
everyone.  Then we'll pick it back up in June 2015.

Finally there's V1101 Aql, the star of 2014 - and no slouch in 2013 
either.  We suspended our campaign a month ago, and Aquila is slumping 
over to the west - BUT it's important that we train our scopes back on 
it now.  Why?  Because, V1101 Aql has the best negative superhumps in 
the sky (among CVs; Hercules X-1 and SS 433 are competitors from other 
realms).  We want to study it from the longest possible yearly baseline, 
to assess how good or how bad the superhump clock is in keeping time. 
Let's observe it over the next month, then pick it up again in May 2015 
- that'll keep the observation gap short.

Other campaigns: status quo ante.  I'll write again in a coupla days.

Joe P

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