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An ancient star city orbiting the Andromeda galaxy is a little *too* ancient. In fact, it's not clear how it can even exist at all! https://www.syfy.com/syfywire/an-ancient-star-city-circles-our-galactic-twin-in-fact-its-too-ancient
2/ It's a globular cluster called RBC EXT8, about 90,000 light years from Andromeda. When they observed it, the astronomers discovered it has incredibly low levels of heavy elements like iron and magnesium. Like around 0.1% the Sun has in it! That's positively anemic.
3/ This means it's *very* old, forming when the Universe was so young it hadn't formed heavy elements yet (those came later, formed inside stars and blown out into space to make more stars). They checked other indicators and they all point to this cluster being extremely old.
4/ Funny thing is, this was found by accident, kinda. The astronomers were observing other clusters, finished early, and said what the heck, let's look at this one. The cluster itself has been known for a long time, and has been observed many times before.
5/ I interrupt this thread to show you a picture of the mighty Omega Centauri, a gigantic globular cluster orbiting the Milky Way, becuase look at it.
LOOK. AT. IT.
LOOK. AT. IT.
6/ Anyway, this cluster was right there this whole time and we just now find out it's truly ancient. That makes me wonder how many other things are up there that may be as old. The Phoenix Star Stream was just discovered and it's also primeval. https://www.syfy.com/syfywire/the-phoenix-star-stream-remnant-of-a-long-dead-stellar-city
7/ There may have been a whole population of such clusters when the Universe was very young, and most of them have since been destroyed. Finding them would be like finding a time capsule to when the galaxy itself was first forming. Maybe even from before.
8/8 And who knows? They may be sitting right in front of our noses. The sky is very big and filled with lots of stuff, and it's hard to observe it all. There are still many, many cool things to find out about what's out there. https://www.syfy.com/syfywire/an-ancient-star-city-circles-our-galactic-twin-in-fact-its-too-ancient
