At the time of creating the galaxy map back in 2012, UY Scuti's distance (and therefore its size) was not known - so there was no particular reason to include it; it was "just another variable star", one of tens of thousands of real-universe variable stars that were not added to the ED universe because they weren't bright enough to be visible in the Sol skybox and the distances were unknown. General opinion a decade ago was "VY Canis Majoris was the largest known star in the galaxy", which is why that star is the largest star in the ED galaxy.
The subject of UY Scuti's non-existence, the general unreliability and impermanence of "largest stars in the galaxy" lists, and the reason why this specific star cannot simply be "added to the game" now, has been raised in numerous threads before. See:
Do you think it should be added to the game? It is a known star and they say its larger then VY Canis Majoris. Would love to have a Stellar tour of super giant stars (and planets too:P) Idk thought it would be cool. Edit forgot to write tour XD
forums.frontier.co.uk
Hello, Fellow travellers! UY Scuti, is one of those stars that might be bigger than that rascal VY Canis Majoris. At least it's a competitor. [yesnod] But where The Hell is it? :eek: Has it gotten another name in the Elite Dangerous Galaxy? Anyone knows? To the FDEV's... It would be really...
forums.frontier.co.uk
Please :(
forums.frontier.co.uk
I've been busy getting to all the biggest known stars in our Galaxy (That I can find anyway) - Still not found the top 3... Anyway cut a long story short - they are way off the correct size, I mean really really WAY OFF! Very disappointing - I guess it will get fixed at some point. So word of...
forums.frontier.co.uk
For a star to be "added to the game" without causing the entire galaxy to be deleted and replaced with a different galaxy that looks almost (but not quite) the same, another star - a procedurally-generated star of identical mass to the "new" star - must be deleted. In effect, the proc-genned star gets overwritten by the "added" star. Which is of course a problem if you want to add a hypergiant star and you want your stars to have "accurate masses", since hypergiant-mass stars rarely if ever generate procedurally. They could hand-code anything else (star class, size, planets, etc) but the mass would be impossible to change without deleting the galaxy. In the most recent thread I linked to above (the link at the top of the list), I postulated a possible scapegoat star system they could sacrifice. The mass would be wrong, but for diehard UY Scuti fans, it would be better than the nothing we have now.