First off, I want to say I love Endless space. You have made a beautiful game with a clear and easy to understand UI, but more importantly, sounds good. I'm still learning Endless space 2, having played it today. 

Now, I see Auriga is an ice world, and I must research Ultra Deep Habitation before my colony ships can make an outpost on them. 

I have that tech, I've colonised an ice world in my starting home system, but it still says I can't colonise Auriga, and it's just after artic colonisation/Ultra-Deep Habitats. 

Bug, missing requirement, need to get the item of fetch quest? Or can no one colonise Auriga for now as it's an early build? 

Edit: I see that artic colonisation leads to Ultra-Deep Habitats. Problem solved, I'll continue enjoying the game!