Jingyi Zhang/NASA
According to a new study from the University of Washington, the carbon in our bodies likely left our galaxy — and returned later, on a trip on a cosmic “conveyor belt.”
Life on Earth could not exist without carbon. But carbon itself could not exist without stars.
Almost all elementswith the exception of hydrogen and helium — including carbon, oxygen and iron — only exist because they were forged in stellar furnaces and later thrown into the cosmos when their stars died.
In a final act of galactic recyclingplanets like ours are formed by incorporation of these stellar atoms into its constitutionbe it iron in the Earth’s core, oxygen in its atmosphere or carbon in the bodies of Earthlings.
A team of researchers from the University of Washington, in the United States, recently confirmed that carbon and other atoms formed in stars do not drift in space until they are dragged to new uses.
The discovery was presented in a published on December 27th in Astrophysical Journal Letters.
For galaxies like ours, which are still actively forming new stars, these atoms take a tortuous journey. They surround their home galaxy in giant chains that extend into intergalactic space.
These cosmic currents, known as circumgalactic mediumresemble giant conveyor belts that push matter outward and draw it back into the galaxy, where gravity and other forces can assemble these raw materials into planets, moons, asteroids, comets and even new stars.
“Think of the circumgalactic medium as a giant train station: It’s constantly pushing material out and pulling it in,” he said. Samantha Garzaresearcher at U.Washington and lead author of the study, at the university.
According to the American astronomer, the heavy elements that stars produce are pushed out of their host galaxy and into the circumgalactic medium. through the explosive death of supernovaewhere they can eventually be pulled back and continue the cycle of star and planet formation.
“The implications for the evolution of galaxies and the nature of the carbon pool available for galaxies to form new stars are exciting,” he explains. Jessica Werkprofessor at UW and co-author of the study.
“The carbon we have in our bodies has most likely passed significant amount of time outside the galaxy!” he adds.
In 2011, a team of scientists confirmed for the first time the long-held theory that star-forming galaxies like ours 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 discovered that the circumgalactic medium of star-forming galaxies also circulates low temperature materiallike or carbon.
“We can now confirm that the circumgalactic medium acts as a reservoir giant for both carbon and oxygen”, explains Garza. “And, at least in star-forming galaxies, This material falls back into the galaxy to continue the recycling process“.
Studying the circumgalactic medium can help scientists understand how this recycling process decreaseswhich will eventually happen in all galaxies — even ours.
One theory is that the slowdown or break in contribution of the circumgalactic medium to the recycling process may explain why a galaxy’s stellar populations decline over long periods of time.
“If we can keep the cycle — pushing material out and pulling it back in — then, theoretically, we have enough fuel to maintain star formation”, concludes Garza.
