With hundreds of billions of stars burning bright, ‘dead’ seems like a bit of an exaggeration. But every galaxy is headed for this fate, including ours.
As long as a galaxy is forming stars, it’s considered to be alive by astronomers.
Our Milky Way contains large star-forming regions, mostly along its spiral arms, indicating stellar life.
But other, mostly elliptical galaxies, stopped forming stars many billions of years ago.
These galaxies are called red-and-dead, because they don’t have any hot, young, blue stars associated with recent star formation.
Since the hottest, bluest stars burn through their fuel the fastest, an intrinsic red color is evidence that no new stars have formed for a long time.
The leading theory is that galaxies require gas to form new stars.
If no stars are forming, the galaxy must be gas-free.
When mergers and interactions occur, star formation accelerates, expelling the critical material.
Only by speeding through the intergalactic medium can all of the interior gas can be truly stripped away.
For the first time, we’ve successfully identified an old red-and-dead galaxy in our cosmic backyard.
Galaxy NGC 1277 moves at over 2,000,000 miles-per-hour through the Perseus cluster, where it hasn’t formed new stars in 10 billion years.
Its stars and globular clusters are entirely red. Unless it devours a new gas source, no new stars will form inside it.
Mostly Mute Monday tells the story of an astronomical object or phenomenon in pictures, visuals, and no more than 200 words.Ethan Siegel is the author of Beyond the Galaxy and Treknology. You can pre-order his third book, currently in development: the Encyclopaedia Cosmologica.