Give acceleration to an object

1

Hello everybody, i have found a code whose purpose is to make an object to follow the mouse arrow. It works perfect, but i would like to add a kind of acceleration to it. That means the closer the object is to the mouse arrow, the faster it moves.

Could somebody find what can i add to this code to make it works?
thanks a lot in advance.

HERE THE CODE:

var Speed:Number = 1 // Velocidad del personaje
var TmpXY:Number = 0;

onEnterFrame = function() {
	gotoSpotX = this._parent._xmouse;
	gotoSpotY = this._parent._ymouse;

	// calculate angle of current position to target position 
	delta_x = this._x-gotoSpotX;
	delta_y = this._y-gotoSpotY;
	targetRotation = -Math.atan2(delta_x, delta_y)/(Math.PI/180);
	if (targetRotation<0){
		targetRotation += 360//Acomoda el angulo para que sea de 360 grados
	}	
	
	// move beetle toward the target and stop when it gets there
	if (Math.sqrt((delta_x*delta_x)+(delta_y*delta_y))>Speed) {
		_y -= Speed*Math.cos(targetRotation*(Math.PI/180));
		_x += Speed*Math.sin(targetRotation*(Math.PI/180));
		this.Fachadas.Parado = false; //Controla fachada de estar parado
	}else{
		this.Fachadas.Parado = true;
	}
	
	// 
	// loop to opposite side of the masked area when the beetle travels off-screen
	if (_y<0) {
		_y = 400;
	}
	if (_y>400) {
		_y = 0;
	}
	if (_x<0) {
		_x = 400;
	}
	if (_x>400) {
		_x = 0;
	}
	
	// Asigna el cambio de fachadas
	if (targetRotation<45){
		this.Fachadas.Angulo = 0;
	}else if (targetRotation<90){
		this.Fachadas.Angulo = 45;
	}else if (targetRotation<135){
		this.Fachadas.Angulo = 90;
	}else if (targetRotation<180){
		this.Fachadas.Angulo = 135;
	}else if (targetRotation<225){
		this.Fachadas.Angulo = 180;
	}else if (targetRotation<270){
		this.Fachadas.Angulo = 225;
	}else if (targetRotation<315){
		this.Fachadas.Angulo = 270;
	}else if (targetRotation<360){
		this.Fachadas.Angulo = 0;
	}