Hi Pat, usually a couple of things cause this but foremost is not matching darks to lights at same temperature.
Also over-stretching and I can see bad (aka hot) pixel trailing but over all it's not a bad result particularly good response to spiral arms Ha.
Try better matching of darks to lights temperature wise and dithering image subs (Dark library avail
here, post #4710249). Temps of sensor can vary wildly from start of imaging to finish and darks can also vary the same. Dithering will help the bad pixel trailing and improve S/N.