How Do Galaxies Die?

The Milky Way galaxy is going to die. In fact, all galaxies will eventually die, when their hydrogen fuel runs out, or they collide with other galaxies and merge into giant elliptical galaxies. But what is the process, and how long has our galaxy got left before it&totally unrecognizable as the Milky Way? Follow us on Twitter: @universetoday Team: Fraser Cain - @fcain Jason Harmer - @jasoncharmer Susie Murph - @susiemmurph Brian Koberlein - @briankoberlein Kevin Gill - @kevinmgill Created by: Fraser Cain and Jason Harmer Edited by: Chad Weber Music: Left Spine Down - “X-Ray” Time to come to grips with our galactic mortality. Not as puny flesh beings, or as a speck of rock, or even the relatively unassuming ball of plasma we orbit. Today we’re going to ponder the lifespan of the galaxy we inhabit, the Milky Way. If we look at a galaxy as a collection of stars, some are like our Sun, and others aren’t. The Sun consumes fuel, converting hydrogen into helium through fusion. It’s been around for 5 billion years, and will probably last for another 5 before it bloats up as a red giant, sheds its outer layers and compresses down into a white dwarf, cooling down until it’s the background temperature of the Universe. So if a galaxy like the Milky Way is just a collection of stars, isn’t that it? Doesn’t a galaxy die when its last star dies? But you already know a galaxy is more than just stars. There’s also vast clouds of gas and dust. Some of it is primordial hydrogen...