We breathe oxygen and nitrogen in the atmosphere every day, but did you know these gases also float in space, around and between galaxies?
Our team captured a high-resolution view of how these elements travel such vast distances across the universe. Our research has now been published in Monthly Notices of the Royal Astronomical Society.
Gas outflows from galaxies occur when a supernova (the explosive death of a star) ejects a mixture of gas and heavy elements such as oxygen, sulfur and even nickel. In addition to polluting space with heavy elements, these outflows also play a key role in star formation throughout the galaxy.
Observing outflows from galaxies is difficult because the gas is many times fainter than the light from the galaxy itself. As a result, we have observed outflows in only a few galaxies in the nearby universe.
The lack of data greatly limits our understanding of their physical properties. This means that every time we see a new outflow, we get a lot of new information.
European Southern Observatory/A. Watts et al., CC BY
Gas outflow regulates star formation
Galaxies grow through star formation, a process regulated by a supply of gas: the raw fuel for new stars. While new stars continue to form, the most massive stars end their lives as supernovae: chemically rich explosions that sweep away surrounding gas and carry it out of the galaxy.
This forms outflow, which is one of the main methods Remove Gas from galaxies. This makes them key regulators of star formation and the growth of galaxies.
They are also an efficient way to distribute the elements needed to form planets like Earth.
Our study focuses on the spiral galaxy NGC 4383, a peculiar object with many stars forming at its center. We have a feeling there’s more going on, maybe even an outflow.
Still, we need more information to find out how this galaxy evolved. To do this, we observed NGC 4383 using one of the most sensitive ground-based instruments in the world: the Multi-Unit Spectroscopic Explorer (MUSE) installed on the European Southern Observatory’s VLT (Very Large Telescope) in the Paranal Mountains of northern Chile.
spectacular picture
The data we got was even more surprising than we imagined.
We clearly see a massive outflow of gas 20,000 light-years from the center of the galaxy. The total mass of gas contained in the outflow is equivalent to 50 million times the mass of the Sun. This galaxy won’t be forming a lot of stars anytime soon.
MUSE takes more than just a picture of a galaxy. Each pixel in an image contains a spectrum, similar to how a rainbow shows us the spectrum of sunlight.
Every element in the universe has unique spectral signatures, and the location of these signatures changes depending on how fast the gas in the galaxy is moving. Therefore, we can also map the movement of gases and chemical elements in NGC 4383 in detail.
We found that this gas cannot escape smoothly, and that the outflow contains turbulent shells and chimney-like structures caused by the violent nature of the supernova explosion that expelled it.
Our ability to track the movement of gases allows us to record gases escaping at breathtaking speeds of over 200 kilometers per second.
We observed chemical signatures of several of these heavy elements, oxygen, sulfur and nitrogen being carried by the outflowing gas, contaminating the space around the galaxy. Now, if I made you worry about space pollution, don’t worry. This is good pollution because these heavy elements are the same ones that make up the world around us and are essential to life as we know it.
Our results are the first from a new project called MAUVE, which aims to understand star formation and the chemical evolution of galaxies in detail. If these numbers are anything to go by, I’d say the biggest surprise is yet to come.
Read more: To understand how galaxies grow, we zoom into the night sky and capture cosmic explosions
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Image Source : theconversation.com