The conventional approach to Solar System formation involves the
collisional growth of the cores of the giant planets in a gas disk
orbiting a star in a region of low-mass star formation, such as
Taurus.
Here we present the alternative scenario, rapid formation
of the gas and ice giant planets in a region of high-mass star
formation, such as Orion or Carina. The ultraviolet fluxes from
nearby massive stars photoevaporate the outer disk, freezing
the orbits of the giant planets, and converting the outer gas
giants into ice giants.
Because most stars form in regions of
high-mass star formation, if this latter scenario is appropriate
for the formation of the Solar System, extrasolar planetary systems
similar to our own may then be commonplace.
This heretical idea
also offers a headstart on the formation of prebiotic molecules
necessary for the origin of life, as well as a natural explanation
for thermally processing primitive materials found in meteorites,
large scale radial mixing of refractories and ices, mixing of
short-lived radioactivities, and transport of stable oxygen
isotopes inward from the outer disk surface.
