Can't start particle system by code!

Hello everyone, I am new to unity and specially to particles in unity. So my plan is to have a dynamic background of stars using particles. Here's my code: public class particlesBackground : MonoBehaviour {

 public int particleCount;
 public double initTime = 10;
 public ParticleSystem PS;   
 
 void Start () {
     PS.Simulate(initTime);
     
 }
 
 void Update () {
     PS.Emit(particleCount);
 }

}

So as I run the game, The particles start as I want (10 sec), but they don't move, I want to start the emission from the current simulated time which is 10sec. Any help?