Nebula flicker problem

Hello, I have a scene where the camera moves slowly whilst showing a nebula. In the batch render there is a noticeable flickering across the nebula. I'm projecting an image of the nebula onto the particle cloud which acts as the physical nebula in maya. I thought it might have something to do with the scale of the nebula vs the size of the image so I experimented with scaling down the particle cloud but I still get flickering. I was just wondering if anyone might know what's causing the problem?