THE TORTURED ACCRETION DISK OF BK LYNCIS

Joe Patterson (Columbia U.)
Jonathan Kemp (Gemini Observatory)
and stations of the Center for Backyard Astrophysics:
Enrique de Miguel (Spain), Tom Krajci (New Mexico), Bob Koff (Colorado), Jerry Foote  (Utah), David Cejudo (Spain), David Skillman (Maryland), Shawn Dvorak (Orlando), Tut Campbell (Arkansas), George Roberts (Tennessee), Josch Hambsch (Belgium), Joe Ulowetz (Illinois), David Messier (Connecticut), Tonny Vanmunster (Belgium)

        BK Lyncis is a 15th magnitude nova-like variable with an orbital period of 107 minutes.     
We report on 2500 hours of time-series photometry with 1-minute time resolution over ten 
observing seasons during 1998-2012.  The star displays large-amplitude positive and
negative superhumps, which vary in amplitude and phase on a timescale of a few months. 
The strength and persistence of the signals make the star a beautiful candidate for detailed     
study ? and the  superhumps are consistent with interpretation as (simultaneous) apsidal    
and nodal precession of the accretion disk.

       BK Lyn's high luminosity has always been remarkable and unexplained ? about fifty       
times greater than its compadres at short orbital period, all of whom are dwarf novae.  In 2012, the star may have had a dwarf-nova outburst, the first ever seen.  We conjecture that the star is "the oldest old nova? ? the remant of the 101 A.D. "guest star", and taking ~2000 years to resume life as a dwarf nova.