Raycast on Particle - Transform

Hello everyone, i ve got this Raycast Script on a particle

var distance : float = 50;

function Update(){

var dir = transform.TransformDirection(Vector3.forward);

var hit : RaycastHit;

if (Physics.Raycast(transform.position, dir, hit, distance)){

if (hit.collider.gameObject.tag == "Object")

{

?????????; } }

}

How could i make the particle shrink and grow accordingly on how close to the gameObject is? Could someone give me hand with this?

Thanks in advance and for your time!