I got a thread that is just banishing.. i'd like to know who is killing my thread and why.

It occurs to me my thread is being killed by the OS, but i'd like to confirm this and if possible to know why it's killing it.

As for the thread, i can assert it has at least 40 min of execution before dying, but it suddenly dies around 5 min.

public void RunWorker()
{
    Thread worker = new Thread(delegate()
    {
        DoSomethingForALongLongTime();
    });

    worker.IsBackground = true;
    worker.SetApartmentState(System.Threading.ApartmentState.STA);
    worker.Start();
}