The recurrent nova CI Aquilae entered the final decline phase a bit before May of 2001 , showing the slowest evolution among the recurrent novae .
Based on the optically thick wind mass-loss theory of the thermonuclear runaway model , we have estimated the turn-off time of the CI Aql 2000 outburst in March of 2001 , after a supersoft X-ray source ( SSS ) phase lasts 150 days from December of 2000 until May of 2001 .
Fitting our theoretical light curves with both the 1917 and 2000 outbursts , we also obtained the WD mass to be M _ { WD } = 1.2 \pm 0.05 ~ { } M _ { \odot } , helium enrichment of ejecta , He/H \sim 0.5 by number , the mass of the hydrogen-rich envelope on the WD of \Delta M \sim 6 \times 10 ^ { -6 } M _ { \odot } at the optical maximum , which is indicating an average mass accretion rate of \dot { M } _ { acc } \sim 0.8 \times 10 ^ { -7 } M _ { \odot } yr ^ { -1 } during the quiescent phase between the 1917 and 2000 outbursts .