Tuesday, 11 July 2017

NGC6802: When star clusters come of age...

Stars are born together in vast hydrogen clouds. Eventually the immense radiation from all of those hot, new-born stars blows the gas cloud away and all that's left is a cluster of stars. Unfortunately in most cases these stars are not destined to remain together. Our galaxy's mighty gravity exerts such a tremendous pull that the mutual gravity of the cluster members is insufficient to keep them united. Slowly, after hundreds of thousands of years, the cluster will start to fall apart and the individual stars will be smeared out into space where they will start their solitary adult lives.

NGC6802's a large but quite distant cluster (5,400 light-years away) in the surprising summer constellation of Vulpecula, the fox. You need to look carefully because it appears small and faint in amateur telescopes, but you'll unmistakingly notice that this cluster's not spherical at all. As you can see on my sketch, our galaxy's gravity's currently tearing it apart! Within a few tens of thousands of years this cluster will be no more and all of its stars will be dispersed into space...

 

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