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The C19 globular cluster in the Milky Way has 1/2500 the metallicity of our sun. This means its stars were formed in the early universe. Is it likely to be the only cluster like this in our galaxy (nothing similar has been found elsewhere) and if so why? C19 globular cluster

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As you already mentioned, its age explains its existence, as old stars have low metallicity since they were formed with minimal enrichment from other stellar generations. In fact, most globular clusters have an abundance of ancient, low-metallicity stars. So low metallicity is not abnormal for a globular cluster, the one you provided just happens to have the lowest metallicity known out of all within our galaxy, at least according to your article.

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  • $\begingroup$ @DaveTheWave I'm slightly confused on how you got the figure of 650 globular clusters comparable to C19 inside of the entire Laniakea Supercluster. Your article doesn't state a percentage of globular clusters of its metallicity? $\endgroup$
    – 4NT4R3S
    Commented Aug 21 at 7:12
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    $\begingroup$ You are correct I made a mistake there should be 100,000 very low metallicity globular clusters in 100,000 galaxies assuming 1 cluster per galaxy with the Milky way representing an average galaxy with just 1 cluster of very low metallicity in it. $\endgroup$
    – user57831
    Commented Aug 21 at 17:40
  • $\begingroup$ @DaveTheWave That figure makes a lot more sense than 650 if we assumed that the average galaxy was the size of the Milky Way, though the majority are a lot smaller. It's possible that such a globular cluster is even rarer if there was one per large galaxy, which is the category our galaxy falls into, but it's hard to pinpoint exactly since we have limited information on extragalactic objects $\endgroup$
    – 4NT4R3S
    Commented Aug 21 at 22:58
  • $\begingroup$ C19 is actually the remnant of a hypothesised globular cluster.l. arxiv.org/abs/2203.02513. Dark matter may have dominated the cluster. $\endgroup$
    – user57831
    Commented Aug 22 at 10:21
  • $\begingroup$ There is an interesting article here about how globular clusters may have started with their own dark matter halos. astrosociety.org/news-publications/mercury-online/…. C19 is very old however it formed. Perhaps dark matter provided the mass density to help its progen itor cloud of gas collapse quickly to begin star formation. $\endgroup$
    – user57831
    Commented Aug 22 at 10:24

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