The number of ways supernovae help tell the story of our universe is kind of countless. From producing many of the elements that make up our body to helping us measure the expansion of the universe, they are just there, saying “Hey, study me, I got the info you need.” 

One of the more low-key ways they affect us is through the production of cosmic rays. These highly accelerated helium cores and other charged particles can impact planetary atmospheres and mix with the surfaces of atmosphereless worlds to create new molecules. Our own Sun also shoots cosmic rays our way, and the combined efforts of our Sun and the universe beyond darkened the surfaces of icy worlds while lighting the atmosphere. And in a new study in Monthly Notices of the Royal Astronomical Society (MNRAS), researchers led by Donna Rodgers-Lee define how cosmic rays over time may change the chemistry of worlds in ways we need to consider as we define where life may or may not form. 

One of the more interesting results of this work is the description of how the Sun’s evolution changes how much of a role external cosmic rays play as compared to solar cosmic rays. Young stars are much more active, and this means their magnetic activity can more effectively push out against the surrounding galaxy and prevent galactic cosmic rays from hitting. At the same time, that active Sun had more cosmic rays of its own to send our way. 

How the cosmic rays from the Sun and from the universe beyond impact a planet is also a function of where that planet is in the solar system. If you are an outer world, the galaxy is going to matter more. If you are an inner world, the Sun is going to try and destroy you when it’s young. Want to survive? Stick to the middle. This seems to be generally good advice for life and for building the chemistry of life.

More Information

Eos article 

“Stellar versus Galactic: the intensity of cosmic rays at the evolving Earth and young exoplanets around Sun-like stars,” D Rodgers-Lee, A M Taylor, A A Vidotto, and T P Downes, 2021 April 5, Monthly Notices of the Royal Astronomical Society