One of the main topics studied by astronomers for the past 20 years was the cause of galaxy death and it seems they have finally figured out what the answer is.
But first let`s establish that, in the universe, there are two main types of galaxies.
The first ones are thriving galaxies, full of cold gas which allows the formation of stars. These are called living galaxies. The second category consists of galaxies without any stars and which lack the ability to create a one. The fact that dead galaxies were not born that way, was well known. Therefore something, some important event, must have happened that turned them barren.
How Galaxies Become Baren
Just like all living things, galaxies need gas to survive, cold gas to be precise. Without it, they are unable to create and sustain stars. So, if they had gas to begin with, what must have happened to cut off their gas supply? Astronomers came up with two theories.
The first one claimed that a sudden, violent event took place in the history of the galaxy which cut off their cold gas supply. An example of this type of event would be a large galaxy that absorbs the gas from a smaller galaxy thanks to a greater gravitational pull.
The other one said, that the shortage of cold gas grew slowly and that the galaxy suffered for a long time before finally running out of gas altogether.
From the title of this article, you can figure out which one was proven correct. Basically, galaxies get chocked to death! How did scientists figure out the right answer?
First, they studied the materials usually found in a star, which are mostly hydrogen and helium, but they also found heavier materials, like types of metals.
What they noticed was that, as a star`s gas supply begins to dry out, the star tends to absorb and create more metal components in order to maintain its mass and in the dead galaxies, the amount of metal detected was a lot larger than it was in healthy galaxies.
This mean that metal accumulated over long periods of time (around 4 billion years) and this shows that the star slowly suffocated rather than had its gas supply abruptly cut off.
Why does this happen to galaxies?
This is what scientists are working to understand at the moment. Their main theory is that, nearby, stronger galaxies, slowly pull away the gas from the smaller galaxy, but it has not yet been confirmed.
However, astronomers are confident in their new tools, the Multi-Object Optical and Near-infrared Spectrograph (MOONS) and the James Webb Space Telescope, with which they hope to reveal the reason why galaxies get slowly choked to death.
Researchers also hope that this will allow them an important glimpse at the beginning of the universe and will permit them to better understand how it was created.
How does this affect Milky Way?
Fortunately, our own galaxy looks like it`s not in any danger of this happening to her, but don`t breathe a sigh of relief just yet. Our galaxy won`t go out that way because scientists have already figure out what will bring forth the end of our Milky Way and there are going to be fireworks!
Milky Way and its neighbor galaxy, Andromeda, are set to collide in about 4 billion years. Andromeda is heading towards Milky Way at a speed of about 110 per second and in 2012, Kepler confirmed that Andromeda`s trajectory is straight towards Milky Way, with no chance of avoiding the collision.
Scientists also have names for the new galaxy that will form from the Andromeda-Milky Way collision: Milkomeda or Milkdromeda.
Image Source: The Telegraph
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