The carbon in our bodies is probably intergalactic

It is very likely that the same carbon present in our bodies has spent a significant amount of time outside our galaxy, the Milky Wayaccording to new research.

Life on Earth could not exist without carbon, but carbon itself could not exist without stars. Almost all elements except hydrogen and helium (including carbon, oxygen, and iron) only exist because they were forged in stellar furnaces and then thrown into the cosmos when their stars died. In a supreme act of galactic recycling, planets like ours are formed by incorporating these star-formed atoms into their composition, whether it is the iron from the Earth’s core, the oxygen from its atmosphere or the carbon from the bodies of Earthlings. .

A team of scientists based in the US and Canada recently confirmed that carbon and other atoms formed by stars are not left idly wandering through space until they are put to new uses. In galaxies like ours, which are still actively forming new stars, these atoms take a circuitous journey. They orbit their home galaxy in giant streams that extend into intergalactic space.

These currents, known as the circumgalactic medium, resemble giant conveyor belts that push material outward and pull it into the galactic interior, where gravity and other forces can assemble these raw materials to form planets, moons, asteroids, comets, and more. even new stars.

“Think of the circumgalactic medium as a giant train station: it’s constantly pushing material out and pulling it in.“Samantha Garza, a team member and doctoral candidate at the University of Washington, said in a statement. “The heavy elements that make up stars are pushed out of their host galaxy and into the circumgalactic medium through their explosive supernova deaths, where they can eventually be pulled inward and continue the cycle of star and planet formation.”

Garza is the lead author of a paper describing these findings that was published December 27 in The Astrophysical Journal Letters.

“The implications for the evolution of galaxies and for the nature of the carbon pool available to galaxies to form new stars are exciting.”said co-author Jessica Werk, a professor at the University of Washington and chair of the Department of Astronomy. “It is very likely that the same carbon present in our bodies has spent a significant amount of time outside the galaxy.”

In 2011, a team of scientists confirmed for the first time the long-held theory that star-forming galaxies, like our own, are surrounded by a circumgalactic medium, and that this large cloud of circulating material includes hot gases enriched with oxygen. Garza, Werk and their colleagues have discovered that the circumgalactic environment of star-forming galaxies also circulates lower-temperature material, such as carbon.

“Now we can confirm that the circumgalactic environment acts as a gigantic reservoir of both carbon and oxygen,” said Garza. “And, at least in galaxies where stars form, we suggest that this material falls back into the galaxy to continue the recycling process.”

Studying the circumgalactic environment could help scientists understand how this recycling process is attenuated, which will eventually happen in all galaxies, including our own. One theory is that a slowdown or breakdown of the circumgalactic medium’s contribution to the recycling process may explain why a galaxy’s stellar populations decline over long periods of time.

“If you can keep the cycle going (pushing material out and pulling it in), then you theoretically have enough fuel to keep stars forming.”Garza said.

For this study, the researchers used the Hubble Space Telescope’s Cosmic Origins Spectrograph. The spectrograph measured how light from nine distant quasars (ultra-bright light sources in the cosmos) is affected by the circumgalactic environment of 11 star-forming galaxies.

Hubble’s readings indicated that some of the quasars’ light was being absorbed by a specific component of the circumgalactic medium: carbon, and a lot of carbon. In some cases, they detected carbon extending nearly 400,000 light years (or four times the diameter of our own galaxy) into intergalactic space.

More research is needed to quantify the total amount of the other elements that make up the circumgalactic medium and to further compare how their compositions differ between galaxies that are still forming large numbers of stars and galaxies that have virtually stopped forming stars. Those answers could shed light not only on when galaxies like ours transform into stellar deserts, but also on why.