  The abundances of 92Nb and 146Sm in the early Solar System are determined
from meteoritic analysis and their stellar production is attributed to the p
process. We investigate if their origin from thermonuclear supernovae deriving
from the explosion of white dwarfs with mass above the Chandrasekhar limit is
in agreement with the abundance of 53Mn, another radionuclide present in the
early Solar System and produced in the same events. A consistent solution for
92Nb and 53Mn cannot be found within the current uncertainties and requires
that the 92Nb/92Mo ratio in the early Solar System is at least 50% lower than
the current nominal value, which is outside its present error bars. A different
solution is to invoke another production site for 92Nb, which we find in the
alpha-rich freezeout during core-collapse supernovae from massive stars.
Whichever scenario we consider, we find that a relatively long time interval of
at least ~10 Myr must have elapsed from when the star-forming region where the
Sun was born was isolated from the interstellar medium and the birth of the
Sun. This is in agreement with results obtained from radionuclides heavier than
iron produced by neutron captures and lends further support to the idea that
the Sun was born in a massive star-forming region together with many thousands
of stellar siblings.
