This is a Hubble Space Telescope photograph of a never-before-seen string of pearls twisted into a corkscrew shape that winds around the cores of two colliding galaxies. The "pearls" are superclusters of blazing, blue-white, newly born stars. The whole assembly must result from the gravitational tidal forces present in the galaxy collision. The serendipitous discovery was made while astronomers were studying the galaxy cluster SDSS J1531+3414.
The underlying physics behind the "beads on a string" shape is related to describing the behavior of self-gravitating clumps of gas. It's analogous to the process where rain falls in drops rather than in continuous filaments from clouds. It's called the Jeans instability, and it can play out on distance scales of enormous orders of magnitude.
Credit: NASA, ESA, and G. Tremblay (European Southern Observatory);
Acknowledgment: M. Gladders and M. Florian (University of Chicago), S. Baum, C. O'Dea, K. Cooke (Rochester Institute of Technology), M. Bayliss (Harvard-Smithsonian Center for Astrophysics), H. Dahle (University of Oslo), T. Davis (European Southern Observatory), J. Rigby (Goddard Space Flight Center), K. Sharon (University of Michigan), E. Soto (The Catholic University of America), and E. Wuyts (Max Planck Institute for Extraterrestrial Physics)