Image of a newly discovered globular cluster. (Photo: Nial Tanvir, Mike Irwin and Avon Huxor)
Read out The Andromeda Nebula is orbited by mysterious globular clusters. British astronomers found these so-called clusters at distances of up to 200, 000 light-years from this neighboring galaxy of the Milky Way. The clusters are extremely different from the previously known globular clusters: they contain about the same number of stars, but they are much broader, so that the individual stars are much farther apart. The mysterious clusters could be the remains of former dwarf galaxies that were captured by the Andromeda galaxy and torn in their gravitational field, suggested study director Nial Tanvir. The researchers discovered the new globular star class when they were using telescopes in the Canary Islands and in Hawaii to study the starry sky. The weak glow of the clusters could be recorded by particularly sensitive sensors. Earlier surveys using an older recording technique had not noticed the clusters.

Astrophysicist Mike Irwin of Cambridge University suggests that the clusters were not directly formed in the Andromeda nebula. Until now, the researchers could not reconcile the formation of globular clusters with theoretical models. To see the newly discovered clusters as captured dwarf galaxies would be more convincing, says Tanvir. "The exciting thing about it is that in the new objects, we're better off talking about tiny galaxies than globular clusters, " says the astrophysicist.

So far, about 200 globular clusters are known in the Milky Way. In the larger Andromeda Nebula, which is about 2.5 million light-years away from the Milky Way, there are about 500. The new globular star class has so far only been found in the Andromeda Nebula.

Nial Tanvir (University of Hertfordshire, Hatfield): Contribution to the annual convention of the British Royal Astronomical Society, Birmingham. display

ddp / Martin Schäfer


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