String of pearls star formation in interacting galaxies

Contrary to common assumptions, Galaxy collisions do not destroy stars, rather these cosmic events trigger new generations of stars, and presumably accompanying planets.

In this NASA/ESA Hubble Space Telescope, Galaxy AM 1054-325 has been distorted into an S-shape from a normal pancake-like spiral shape by the gravitational pull of a neighbouring galaxy, resulting in the formation of newborn clusters of stars along a stretched-out tidal tail for thousands of light-years, resembling a string of pearls.

Hubble observed 12 interacting galaxies that have long, tadpole-like tidal tails of gas, dust, and a plethora of stars, thanks to the telescope's exquisite sharpness and sensitivity to ultraviolet light 425 clusters of newborn stars along these tails were uncovered, with each containing as many as 1 million blue, newborn stars.

Utilizing new observations and archival data, astronomers determined the ages and masses of tidal tail star clusters and found that these clusters are very young - only 10 million years old. - and appear to be forming consistently along tails that extend for thousands of light-years.

"It's a surprise to see lots of the young objects in the tails. It tells us a lot about cluster formation efficiency. With tidal tails, you will build up new generations of stars that otherwise might not have existed," said lead author Michael Rodruck of Randolph-Macon College in Ashland, Virginia.

Astronomers believe that string-of-pearls star formation may have been more common in the early universe when galaxy collisions were more frequent. The nearby galaxies observed by Hubble are a proxy for these ancient cosmic occurrences, offering a window into the distant past.