I just tried this!
@chew:
That makes sense to me. Increasing an object's mass 80fold without changing the velocities of its moons would resulting in the moons gaining very high eccentricities, such as ones which would result in impact with the primary. Besides, even if the velocity was changed, Io would be torn apart by gravitational tides. Also, due to being less than 0.02 AU from a 3000 kelvin, 0.08 solar mass star, the surviving moons would be subjected to radiation and tidal heating which would quickly boil off all their volatiles, leaving Ganymede and Callisto at only half their present masses. Europa would lose less mass comparatively, but any life it had would be toast, and taking into account both radiation and tidal heating, it would probably end up as a huge, elongated droplet of magma flying around Jupiter once every 8.79 hours.
Life on Earth would be VERY affected. Even if it stayed in the habitable zone (which it might not do over millions of years just because it did over a few hundred or thousand), Jupiter's new high mass would scatter the asteroid belt in all directions, subjecting Earth to a cosmic firing squad. Over the next few million years, repeated asteroid impacts (picture being hit by a hundred asteroids as large as or larger than the K-T impactor, each coming in just when the affects of the previous ones had worn off. Also, there would be plenty of smaller, but still city-destroying impacts thrown in as a side bonus) would at the very least kill off the vast majority of species on Earth, including possibly all multicellular life outside the oceans. If we got really unlucky and a really big asteroid hit us (such as Vesta or Pallas) our planet would be completely sterilized.