Life on Earth depends on carbon, which is formed in stars and later distributed throughout the galaxy when stars die. This process of stellar recycling creates the atoms that make up planets, including Earth. A team of scientists recently discovered that these star-formed atoms travel through a galaxy’s circumgalactic medium in a constant cycle. This material is pushed out by exploding stars and then pulled back into the galaxy, where it can be used to form new stars, planets, and other celestial bodies.
The circumgalactic medium acts like a giant train station, constantly moving material in and out of galaxies. This large, circulating cloud of material contains elements like carbon and oxygen, which are essential for star and planet formation. The researchers used the Hubble Space Telescope to study how light from distant quasars is affected by the circumgalactic medium of star-forming galaxies. They found large amounts of carbon in this medium, suggesting that it serves as a reservoir for elements needed for new star formation.
Understanding the circumgalactic medium could provide insights into how galaxies evolve over time. Eventually, all galaxies will experience a decline in star formation, and studying this process could help scientists understand why this happens. By studying the compositions of the circumgalactic medium in different types of galaxies, researchers hope to determine when and why galaxies transition into stellar deserts where new stars are no longer formed.
The research team’s findings have important implications for galaxy evolution and the availability of carbon for forming new stars. By keeping the cycle of pushing material out and pulling it back in, galaxies can continue to fuel star formation. Further research is needed to quantify the full extent of other elements in the circumgalactic medium and to compare compositions between galaxies that are actively forming stars and those that have ceased star formation.
This study sheds light on the complex processes that govern the formation and evolution of galaxies. By understanding how elements like carbon are recycled through galaxies, scientists can gain valuable insights into the mechanisms that drive star and planet formation. The researchers’ work highlights the interconnectedness of the cosmos and the importance of studying the circumgalactic medium to unlock the mysteries of the universe.