From the smallest microbe to the most powerful oak, death is as certain for the top as for the bottom, even for the most powerful galaxies.
The process, however, is not quick. A disturbing new Hubble photo of the 1947 NGC galaxy demonstrates this well: even from a distance of about 45.4 million light-years away (in the southern constellation of Dorado), we can see that the galaxy is slowly declining.
The track is in the dust and gas. A galaxy at the height of its life will be filled with things, using it to create new stars. Eventually, the star stuff will be over, and that’s what astronomers believe we’re seeing with NGC 1947.
It is a rare type of galaxy known as a lenticular, disk-shaped galaxy, such as the Milky Way or Andromeda, but without the spiral arms. NGC 1947 used to have spiral arms, but it has exhausted almost all the gas and dust that gave them structure; only a few stretches remain, illuminated by the light of the stars.
(ESA / Hubble and NASA, D. Rosario; L. Shatz)
Galaxies that have not created new stars in billions of years are considered dead, but the Universe is not old enough for us to see what happens once all these stars die.
What about our own galaxy? In fact, the Milky Way may have died at least once about 7 billion years ago; revived after a period of 2 billion years, during which a whole host of stars died, which were supernovae and ejected their outer envelopes into space, filling the galaxy with material to make new ones. stars.
Currently, the Milky Way has a relatively slow star formation rate, between 1 and 2 solar masses a year, but it doesn’t hurt for new materials either. Our galaxy is a cannibal, with a history of absorption of other galaxies and all of their wonderful star-forming material during its 13.5 billion-year lifespan, and is far from finished.
Eventually, the Magellanic clouds will join the Milky Way and we will be heading for a merger with the Andromeda galaxy a few million years from now. This could trigger a period of high star formation as tidal interactions impact and compress the material of the two galaxies.
Based on space observations around NGC 1947, an injection of fresh material from a fusion with another galaxy is unlikely, at least soon. It will continue to fade, until only a raft of dead stars remains.
You can download versions of this image in wallpaper format from the ESA website.