Carbon atoms in your body traveled 400,000 light-years through space before creating you

Every atom of carbon in your body has an incredible story to tell. Before becoming part of you, the carbon atom likely spent time not just in other living things, but also floating in the vast spaces between stars.

And now, scientists have discovered something remarkable about this cosmic journey – these carbon atoms don’t just drift aimlessly through space. They’re part of a massive galactic recycling system that keeps our universe’s star-forming factories running.

The remarkable research comes from a team led by Samantha Garza, a doctoral candidate at the University of Washington.

The findings shed new light on how galaxies, like our Milky Way, maintain their ability to form new stars through a complex system of cosmic circulation.

Carbon and the human body — the basics

Carbon atoms are like the building blocks of life, making up a huge part of the human body. In fact, about 18% of your body weight comes from carbon.

Carbon forms the backbone of all organic molecules, which include proteins, fats, carbohydrates, and nucleic acids like DNA. These molecules are essential for everything your body does, from carrying energy to building cells.

For example, glucose, a simple sugar made of carbon atoms, is one of the main sources of energy for your cells. Without carbon, none of these vital molecules would exist.

When you breathe in oxygen, your body uses it to break down carbon-based molecules in a process called metabolism. This process releases energy that your body needs to function.

At the same time, carbon atoms are also involved in the removal of waste through exhaling carbon dioxide (CO2), which is a byproduct of metabolism. Your body works hard to maintain a balance of carbon by taking it in through food and releasing it as waste.

Conveyor belt in space cycles carbon

Galaxies have their own version of the Earth’s water cycle, but instead of water they cycle elements, like carbon and oxygen, through the circumgalactic medium.

It’s like a massive conveyor belt system that extends far beyond the visible edges of galaxies, pushing material out into space and then drawing it back in.

“Think of the circumgalactic medium as a giant train station,” Garza said.

“It is constantly pushing material out and pulling it back in. The heavy elements that stars make get pushed out of their host galaxy and into the circumgalactic medium through their explosive supernovae deaths, where they can eventually get pulled back in and continue the cycle of star and planet formation,” she explained.

Detecting carbon atoms in space

This discovery builds on a breakthrough from 2011 when scientists first confirmed that star-forming galaxies are surrounded by this circumgalactic medium.

Back then, the experts found hot, oxygen-rich gases in this region. Now, Garza’s team has shown that cooler materials, particularly carbon, are also part of this cosmic recycling stream.

The scale of this system is mind-boggling. Using the Cosmic Origins Spectrograph on the Hubble Space Telescope, the team detected carbon extending nearly 400,000 light-years into space – that’s four times the diameter of our entire galaxy.

The experts made these measurements by studying how light from distant quasars (incredibly bright cosmic objects) was affected by the carbon-rich material in the circumgalactic medium of 11 different star-forming galaxies in space.

Carbon traveled outside of our galaxy

“The same carbon in our bodies most likely spent a significant amount of time outside of the galaxy!” noted Jessica Werk, a professor and chair of the Department of Astronomy at the University of Washington, who co-authored the study.

This recycling system might hold the key to understanding why some galaxies eventually stop forming new stars.

Think of it like a city’s recycling program – if the collection and processing system breaks down, new products can’t be made from the recycled materials.

Similarly, if a galaxy’s circumgalactic medium stops cycling materials like carbon effectively, star formation in space could grind to a halt.

Future of star formation

“If you can keep the cycle going – pushing material out and pulling it back in – then theoretically you have enough fuel to keep star formation going,” noted Garza.

But what happens when this cycle slows down or stops? That’s one of the next big questions researchers hope to answer.

The study, published in the Astrophysical Journal Letters, opens up new avenues for understanding galaxy evolution.

The research team included scientists from institutions across the U.S. and Canada. The experts are now working to quantify other elements in the circumgalactic medium and compare how the composition of active star-forming galaxies differs from those that have mostly stopped making new stars in space.

A vast carbon recycling system

The research reminds us that we’re part of something much bigger than ourselves. The atoms that make up our bodies aren’t just stardust – they are active participants in an ongoing cosmic cycle of creation and renewal.

Each time you take a breath, you’re breathing in carbon atoms that might have once been part of this vast space recycling system.

The study was supported by NASA and the National Science Foundation, demonstrating the continued importance of these institutions in advancing our understanding of the universe.

As we look to the future, this work could help explain not just how galaxies like ours maintain their stellar populations, but also why some galaxies eventually transition into cosmic deserts where new stars cease to form.

The next time you look up at the night sky, remember that you’re not just looking at distant stars – you’re looking at a vast cosmic recycling system that has been running for billions of years, and may have played a crucial role in making you who you are today.

The study is published in the journal The Astrophysical Journal Letters.

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