  A critical constraint on solar system formation is the high
$^{26}$Al/$^{27}$Al abundance ratio of 5 $\times 10^{-5}$ at the time of
formation, which was about 17 times higher than the average Galactic ratio,
while the $^{60}$Fe/$^{56}$Fe value was about $2 \times 10^{-8}$, lower than
the Galactic value. This challenges the assumption that a nearby supernova was
responsible for the injection of these short-lived radionuclides into the early
solar system. We show that this conundrum can be resolved if the Solar System
was formed by triggered star formation at the edge of a Wolf-Rayet (W-R)
bubble. Aluminium-26 is produced during the evolution of the massive star,
released in the wind during the W-R phase, and condenses into dust grains that
are seen around W-R stars. The dust grains survive passage through the reverse
shock and the low density shocked wind, reach the dense shell swept-up by the
bubble, detach from the decelerated wind and are injected into the shell. Some
portions of this shell subsequently collapses to form the dense cores that give
rise to solar-type systems. The subsequent aspherical supernova does not inject
appreciable amounts of $^{60}$Fe into the proto-solar-system, thus accounting
for the observed low abundance of $^{60}$Fe. We discuss the details of various
processes within the model and conclude that it is a viable model that can
explain the initial abundances of $^{26}$Al and $^{60}$Fe. We estimate that
1-16% of all Sun-like stars could have formed in such a setting of triggered
star formation in the shell of a WR bubble.
