10 AU is roughly Saturn and star brightness has a lot to do with habitable zone size.
Atmospheric thickness is important to achieving sufficient heat for liquid water, it might be possible to have internally generated heating.
Another option... (rabbit hole for LDIS archaeology division) there may be some ancient terraforming mechanisms/artifacts that increase the total captured star light on the planet.
Aha, indeed that was a error on my part!The star however is dimmer & cooler then our sun (albeit a bit larger) Still makes the second terrestrial hard to explain, as it's atmospheric pressure is far below earth's. Large internal heating process and high geologic activity would be an option and certainly a possibility as it has 3 moons so that'll provide some good internal heating. Would make the planet not very friendly to human habitation however.
The Alien tech did cross my mind, but using it as explanation can lead you to fall into logic/RP traps of the kind 'Aliens/Wizard did it!' Prefer to use a RL explanation when I can, untill it's to far fetched and alien tech/magic sounds more probable. Still doesn't rule out some ruins are left there from some previous settlement/civ.
LDIS subsidiary is currently working to produce Polyarmids off of Ayem.
Edit: You can add Supercomputers!
Aha good to know! Still gathering information about the Ayem industries so great to have this bit!
To readers: having a discussion with folks, making your worldbuilding an effort of multiple people helps in fleshing it out, but also helps with contributions, especially if you (like me!) only started recently and are prone to mistakes. People can also have idea's and suggestions you haven't tought of in the first place, enhancing the creative process.
It does depend of course on the nature of your worldbuilding project, in my case it's meant as a continious, expanding project over time.