State-of-the-art simulations shed light on how galaxies die — and how we can determine the cause of death. M87 is a nearby, quiescent elliptical galaxy. As star formation has ceased, only older stars, redder in appearance, remain, giving the galaxy it's "red and dead" moniker. NASA, ESA and the Hubble Heritage Team (STScI/AURA); Acknowledgment: P. Cote (Herzberg Institute of Astrophysics) and E. Baltz (Stanford University) Galaxies don’t form stars forever. Somehow, vibrant, young, star-filled systems turn into quiet, “dead” galaxies. Astronomers have long known that galaxies don’t all shut down the same way, yet identifying what makes a galaxy go quiet has been tricky. Now, astronomers using a high-resolution computer simulation of the universe have come a step closer to understanding how galaxies die, by developing a method to map galaxies’ star formation (or lack thereof) using four simple measurements.     Stars form within clouds of cold gas.…