When galaxies get close enough to each other, tidal forces can tug entire star systems out of place, distorting the shapes of the interacting pair in sometimes dramatic fashion. When galaxies with active galactic nuclei interact, the result can be spectacular, as in this Hubble Space Telescope view of Arp 282, made up of Seyfert galaxy NGC 169 (bottom) and IC 1559 (top). Hidden in the cores of both galaxies are supermassive black holes, actively feasting on surrounding stars, gas and dust. Delicate streams of matter can be seen visibly connecting the two galaxies in a dramatic, 3D-like demonstration of titanic tidal interactions.
In many ways stars are like living beings. They’re born; they live; they die. And they even have a heartbeat. Near the end of their lifetime they begin to pulsate, increasing and decreasing their brightness by a large amount every few hundred days. Using a novel technique, astronomers have detected thousands of stellar “pulses” in the galaxy Messier 87 (M87). Their measurements offer a new way of determining a galaxy’s age.
The Atacama Large Millimetre/submillimetre Array has produced a spectacularly detailed image of a distant galaxy known as SDP.81 that is being gravitationally lensed. The image shows a magnified view of the galaxy’s star-forming regions, the likes of which have never been seen before at this level of detail in a galaxy so remote.