The Large Magellanic Cloud (LMC), which is the nearest galaxy to our Milky Way at about 159,000 light years, is home to about 60 globular clusters. Pictured here is one of these great balls of stars, namely NGC 2210, which shines in the night sky at magnitude +11 in the Southern Hemisphere constellation of Doradus. Imaged by the Hubble Space Telescope, it is packed with hundreds of thousands of stars.
NGC 2210 is a bit of an outlier. In 2017 astronomers led by Rachel Wagner-Kaiser of the University of Florida measured the ages of six globular clusters in the LMC and found their mean age to be over 13 billion years old, within just 200 to 400 million years of the birth of our own Milky Way Galaxy’s most ancient globular clusters. The inference is that the LMC’s globular clusters formed at the same time as the Milky Way’s globular clusters, yet back then the two galaxies were presumably far apart – the LMC is thought to be passing close to the Milky Way for the first time. Is there something fundamental that caused globular clusters in two galaxies, and perhaps all over the Universe, to form at the same time?
Not all of them formed at the same time. NGC 2210 is actually younger, at 11.6 billion years old. Why NGC 2210 formed a little later than the others is just one more mystery to be solved.
Image: ESA/Hubble/NASA/A. Sarajedini/F. Niederhofer.