  The recent discovery of the first V-type asteroid in the middle belt, (21238)
1995WV7, located at ~2.54 AU, raises the question of whether it came from (4)
Vesta or not. In this paper, we present spectroscopic observations indicating
the existence of another V-type asteroid at ~2.53 AU, (40521) 1999RL95, and we
investigate the possibility that these two asteroids evolved from the Vesta
family to their present orbits by drifting in semi-major axis due to the
Yarkovsky effect. The main problem with this scenario is that the asteroids
need to cross the 3/1 mean motion resonance with Jupiter, which is highly
unstable. Combining numerical simulations of the orbital evolution, that
include the Yarkovsky effect, with Monte Carlo models, we compute the
probability of an asteroid of given diameter D to evolve from the Vesta family
and to cross over the 3/1 resonance, reaching a stable orbit in the middle
belt. Our results indicate that an asteroid like (21238) 1995WV7 has a low
probability of having evolved through this mechanism due to its large size (~5
km). However, the mechanism might explain the orbit of smaller bodies like
(40521) 1999RL95 (~3 km), provided that we assume that the Vesta family formed
> 3.5 Gy ago. We estimate that about 10% or more of the V-type bodies with D>1
km may come from the Vesta family by crossing over the 3/1 resonance. The
remaining 90% must have a different origin.
