I’ve used this fact a gazillion times; every atom in your body has been through the core of a star! The carbon in our bones formed through fusion like many other elements and was thrown out into space to seed the cosmos with the elements for life. A team of researchers have been exploring this journey, tracking a giant conveyor belt that surrounds the Galaxy and the results are surprising.
Carbon is one of the fundamental elements inside our bodies. The first elements that appeared after the Universe formed 13.7 billion years ago was mostly hydrogen and a little helium. The carbon in our bodies has been synthesised inside stars in a process known as nucleosynthesis.
As stars evolve, they undergo a series of fusion reactions fusing hydrogen atoms into helium, then helium nuclei into carbon. Three helium-4 atoms combine to create an atom of carbon-12. Temperatures of around 100 million kelvin are needed for this process and, as it progresses, an outward pushing force known as the thermonuclear force is generated. During the main part of a stars life, this is balanced by the inward force of gravity.
At a point in the evolution of the star which is determined by its mass, the material that composes the star is ejected out into space through a planetary nebula or supernova explosion. Ultimately these heavier elements find their way to new stellar nurseries where the next generation of stars and even planets and life may form.
Scientists from the United States and Canada have shown in their latest research that the liberated carbon atoms don’t just drift aimlessly through space until they find their new home. Instead, their studies reveal that in galaxies like the Milky Way where star formation is still underway, the atoms take a less direct route. Giant currents known as the circumgalactic medium circle the galaxy and extend out into intergalactic space. The currents drag the newly ejected stellar material out and draw it back in to the interior of the galaxy where it forms new stars.
To reach this conclusion, the team used the Cosmic Origins Spectrograph on the Hubble Space Telescope. This instrument enabled the study of the ultraviolet radiation in detail from nine distant quasars. They explored how they were effected by circumgalactic medium of 11 other galaxies that had active star forming regions. The results showed the absorption of light by carbon. One galaxy showed carbon caught up in the current extending to a distance of nearly 400,000 light years. To put that into context that is around four times the diameter of our own Milky Way Galaxy!
It’s quite an eye opening discovery and certainly repaints the picture of stellar evolution. Instead of the gentle drifting through space of elements ejected from stars, the journey is far more tumultuous. As always though, more research is needed to fully understand the circumgalactic medium and to understand its impact on stellar formation. Not only will we get a better understanding of the lives of stars but how galaxies evolve too and why some host active star formation and others are stellar deserts.
Source : The carbon in our bodies probably left the galaxy and came back on cosmic ‘conveyer belt’