We present optical ( B , V , R _ { c } , I _ { c } and y ) and near infrared ( J , H and K _ { s } ) photometric and spectroscopic observations of a classical nova V1280 Scorpii for five years from 2007 to 2011 .
Our photometric observations show a declining event in optical bands shortly after the maximum light which continues \sim 250 days .
The event is most probably caused by a dust formation .
The event is accompanied by a short ( \sim 30 days ) re-brightening episode ( \sim 2.5 mag in V ) , which suggests a re-ignition of the surface nuclear burning .
After 2008 , the y band observations show a very long plateau at around y = 10.5 for more than 1000 days until April 2011 ( \sim 1500 days after the maximum light ) .
The nova had taken a very long time ( \sim 50 months ) before entering the nebular phase ( clear detection of both [ O iii ] 4959 and 5007 ) and is still continuing to generate the wind caused by H-burning .
The finding suggests that V1280 Sco is going through the historically slowest evolution .
The interval from the maximum light ( 2007 February 16 ) to the beginning of the nebular phase is longer than any previously known slow novae : V723 Cas ( 18 months ) , RR Pic ( 10 months ) , or HR Del ( 8 months ) .
It suggests that the mass of a white dwarf in the V1280 Sco system might be 0.6 M _ { \mathrm { \sun } } or smaller .
The distance , based on our measurements of the expansion velocity combined with the directly measured size of the dust shell , is estimated to be 1.1 \pm 0.5 kpc .