Astronomers spotted a “river of stars” in the image. The image in question was actually taken by Hubble in 2010, but the telescope provides a large number of images and data, which can be searched for various questions, so that nothing notices the thing that has now been discovered.
The image shows the so-called Hickson Compact Group 31 (HCG 31), a group of closely spaced dwarf galaxies. The image shows that not only do objects have a purely gravitational effect on each other as a whole, but that gravitational forces also ensure that entire stars move back and forth between small galaxies.
Hubble uptake of HCG 31
In the photo you can see a large bright spot in the upper middle. This is an object listed as NGC 1741 in catalogues – but they are actually two dwarf galaxies that are merging. Shown to the right is a cigar-shaped dwarf galaxy associated with NGC 1741 by a faint band of wandering stars.
A fourth galaxy can be seen at the bottom of the image. This also has astrology related to the above things. These are very small objects that appear to have only recently been pulled (measured on cosmic time scales) from the star-forming region. The very bright object in the center is a star located between Earth and HCG 31 and is unrelated to the galaxy cluster.
HCG 31 is located “only” at 166 million light-years from Earth – not a particularly large distance by cosmic standards. This must be the prerequisite for being able to see rivers of stars at all. However, it can be assumed that this is not a significant special case, but nearby galaxies often exchange not only gravitational forces and possibly gas, but entire stars with each other.
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