V-type asteroids are bodies whose surfaces are constituted of basalt .
In the Main Asteroid Belt , most of these asteroids are assumed to come from the basaltic crust of asteroid ( 4 ) Vesta .
This idea is mainly supported by ( i ) the fact that almost all the known V-type asteroids are in the same region of the belt as ( 4 ) Vesta , i.e .
the inner belt ( semi-major axis 2.1 < a < 2.5 AU ) , ( ii ) the existence of a dynamical asteroid family associated to ( 4 ) Vesta , and ( iii ) the observational evidence of at least one large craterization event on Vesta ’ s surface .
One V-type asteroid that is difficult to fit in this scenario is ( 1459 ) Magnya , located in the outer asteroid belt , i.e .
too far away from ( 4 ) Vesta as to have a real possibility of coming from it .

The recent discovery of the first V-type asteroid in the middle belt ( 2.5 < a < 2.8 AU ) , ( 21238 ) 1995WV7 ( Binzel et al .
2006 , DPS 38 , # 71.06 ; Hammergren et al .
2006 , astro-ph/0609420 ) , located at \sim 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 \sim 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 ( less than 10 % ) of having evolved through this mechanism due to its large size ( D \sim 5 km ) , because the Yarkovsky effect is less efficient for larger arteroids .
However , the mechanism might explain the orbit of smaller bodies like ( 40521 ) 1999RL95 ( D \sim 3 km ) , provided that we assume that the Vesta family formed \gtrsim 3.5 Gy ago .
We estimate the debiased population of V-type asteroids that might exist in the same region as ( 21238 ) and ( 40521 ) ( 2.5 < a \lesssim 2.62 AU ) and conclude 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 .