So, I don't claim to be any kind of pro arcane mage, my guild is still progressing through hc. But maybe I can help you out a bit. Here's my logs https://www.warcraftlogs.com/rankings/character/17191329/latest
From what I can see, you're using mirror images. I would suggest using rune of power, you will get more damage out of it.
From your logs, you seem to be struggling on all bosses, not just star augur. Maybe practice your rotation a bit. One thing that may be affecting your dps is too much movement. Try to move only when necessary. For example, on star augur you can blink out of
