From the smallest microbes to the most powerful oak trees, death is just as true for the above as for the strongest galaxies.
However, the process is not fast. A ghostly new Hubble photograph of the NGC 1947 galaxy shows this well: even at 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 clue lies in the dust and gas. A galaxy in the prime of its life will be filled with the good and use it to make new stars. Eventually the asterisks will run out, and this is what astronomers believe with NGC 1947.
It is a rare type of galaxy known as a lenticular galaxy – disk-shaped, like the Milky Way or Andromeda, but without the spiral arms. NGC 1947 used to have spiral arms, but it used up almost all the gas and dust that gave structure; all that is left are some sneaky cars, illuminated by starlight.
(ESA / Hubble & NASA, D. Rosario; L. Shatz)
Galaxies that did not create new stars for billions of years are considered dead, but the Universe is not old enough to see what happens when all the stars die.
What about our own galaxy? In fact, the Milky Way may have died at least once about 7 billion years ago; it revived after a period of 2 billion years, during which a whole bunch of stars died, went supernovae and threw their outer envelopes into space and filled the galaxy with material to make new stars.
The galaxy currently has a relatively slow rate of star formation, about 1 to 2 solar masses per year, but it is also not damaged by new material. Our galaxy is a cannibal with a history of recording other galaxies and all their amazing star-forming material during its 13.5 billion-year lifespan, and it’s far from over.
Eventually, the Magellanic Clouds will creep into the Milky Way, and within a few billion years we will be merging with the Andromeda galaxy. This can cause a period of increased star formation, as the tidal interaction material in both galaxies shocks and compresses.
Based on observations of space around NGC 1947, the injection of fresh material from a merger with another galaxy is unlikely, at least soon. It’s going to keep fading until all that’s left is a bunch of dead stars.
You can download the version of the background size of this image from the ESA website.