  X-ray bursts from compact stars is believed to be due to type I thermonuclear
processes which are short lived, typically ~ 10 to 100 s. There are some low
mass X-ray binaries (LMXB) like 4U 1820-30, 4U 1636-53, KS 1731-260 and Serpens
X-1, known as Super Bursters (SB) which emit X-rays close to the Eddington
luminosity limit for long periods of several hours. Recently there are reports
of some long bursters (LB), which have bursts lasting 6-25 minutes, whereas the
4U 1735-44 has a burst period of 86 minutes. We suggest that these bursts from
SB and LB may be due to breaking and re-formation of diquark pairs, on the
surface of realistic strange quark stars. We use the beta equilibrated u, d and
s quark model of Dey et al. (1998) and Li et al. (1999a and 1999b) and allow
for spin dependent hyperfine interaction between quarks. The interaction
produces pairing of specific colour-spin diquarks, leading to further lowering
of energy by several MeV-s for each pair, on the average. Diquarks are expected
to break up due to the explosion and shock of the TN process. The subsequent
production of copious diquark pairing may produce sufficient energy to produce
the very long bursts seen in SB or LB. The estimated total energy liberated,
10^{42} ergs, can be explained in our model with the calculated pair density ~
0.275/fm^3 and a surface thickness of only half a micron, if the entire surface
is involved. The depth of the surface involved in the process may be only few
microns if the process is restricted to small part of the surface near the
equator as suggested by Bildsten.
