What provides carriers with external immunity?

[Rustayne]

I have 4 carriers in a system that has been emptied out.  There is no supply for me here as it is 2 jumps from my bottleneck.  The carriers have had as high as 35x immunity to damage, and I'm curious what is providing it.

[Orelius]

I think that number is derived from the number of ships that have to be killed before the carriers can deploy.  I'm not too sure as I often don't see carriers, so take my hypothesis with a grain of salt.

[TechSY730]

Yea, I think that if there are above a certain number of other mobile military (non-carrier) AI enemy units on that planet, the carriers are invincible. This is to prevent a ton of ships being ejected and the game slowing to a crawl. Thankfully, the cap is pretty high, like 2000 or something, and the carriers are probably not as threatening as those 2000 ships, so you probably aren't missing much but not being able to take the carriers out right away.