We have been conducting a long-term (1988-1998) photometric study of the no
va-like variable TT Arietis. The main periodic signal in the star's light c
urve normally occurs at a period that varies but averages similar to 0.1329
days, which is about 3.5% shorter than the orbital period of the binary. I
n 1997, this signal disappeared and was replaced by a stronger signal 8.5%
longer than the orbital period. This new wave strongly resembles the "super
humps" commonly seen in SU UMa-type dwarf novae during superoutburst. In su
perhump parlance, we could say that a negative superhump was replaced by a
positive superhump (P > P-orb). This could signify the development of an ec
centric instability in the accretion disk. The two superhumps probably sign
ify two types of disk precession: apsidal advance and nodal regression. TT
Ari is an excellent candidate for observational studies that probe the orig
in of superhumps.