Astronomers are watching a cluster of stars called a globular cluster fall to its doom. The cluster, called VVV CL002, is speeding towards the centre of the Milky Way, where it is certain to be destroyed. This process has probably happened countless times over the history of the galaxy, but this is the first time we have witnessed it.
VVV CL002 is the closest known globular cluster to the centre of the galaxy, at a distance of just 1300 light years. It was discovered in 2021, and now at the University of Tokyo and his colleagues have measured its orbit and the compositions of some of its constituent stars more precisely than ever before.
The new observations indicate that the cluster is relatively old. It formed in the bulge of stars around the centre of the galaxy, rather than in the more spread-out cloud of stars called the galactic halo or in a different galaxy that was later swallowed up by the Milky Way. Simulations showed that its orbit reaches within about 620 light years of galactic centre 鈥� so close that it isn鈥檛 expected to survive for long.
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With such a tight orbit, the most likely scenario is that the cluster is in the process of falling into the centre of the galaxy, where it will surely be ripped apart.聽Researchers believe that many clusters have been similarly destroyed over the course of the galaxy鈥檚 history, making a significant contribution to the extraordinarily dense population of stars at galactic centre.
However, the fact that galactic centre is so dense with stars and dust has made these events tough to observe, and VVV CL002 is the first cluster we have ever seen undergoing this process. 鈥淭here are some globular clusters located at similarly small distances, and they are probably being disrupted too,鈥� says Matsunaga. 鈥淭he problem is, it isn鈥檛 easy to observe such objects.鈥�
A precise measurement of how long this cluster will last would require knowledge of its speed that we don鈥檛 have yet, but Matsunaga estimates that it will last hundreds of millions of years more before being shredded. 鈥淎 hundred million years is too long for humans to watch it, but too short to give us many objects in this particular process to see,鈥� he says. Studying objects like this could give us some insight into the evolution of our galaxy鈥檚 structure.
arXiv
