Why Nuclear Astrophysics?
What is Nuclear Astrophysics? Why is it interesting at all? Who is interested in this field? And why?
Some people may wonder how could Nuclear Physics be related to Astrophysics. After all, nuclear physics deals with tiny physical objects, while astrophysics deals with large objects such as stars. Furthermore, those two fields use different tools, different methods, and, apparently, different physical theories.
However, this is not entirely true. In fact, there is a tight connection between the two disciplines. In fact, active stars (such as our sun) are physical objects that exist on the balance between a continuous nuclear activity and their own gravity. The lifetime, brightness, and many other physical characteristics of stars are determined by their nuclear content and reactions. A nuclear astrophysicist is studying those nuclear reactions, and their impact on stars and some other astrophysical scenarios, and on the chemical composition of the galaxy.
Nuclear physics is important for Astrophysics, since understanding stars, supernovae and other astrophysical phenomena must take into account a lot of nuclear physics. On the other hand, Astrophysics is important for Nuclear Physics. Although we have nuclear reactors and particle accelerators, we do not see so much nuclear physics in natural environment on earth. Earth is simply a graveyard in terms of nuclear physics. Consequently, we are naturally exposed to only a fraction of the variety of nuclei that nature allows. So, we can go to the lab and study what we have, or we can work out ways to expand our reach and study some more exotic nuclei, but if we seek to understand natural events that actually involve nuclear physics, the real place to look for is the galaxy.
Lastly, Nuclear Astrophysics is the field that directly addressed the basic question of what is the origin of the chemical elements. Of course, we know that the Big Bang created hydrogen, helium, and some amount of light elements, and we know that all the other elements were created in stars and other astrophysical scenarios such as neutron-star mergers. But we still have a lot of missing information, and nuclear astrophysicists are combining studies from astronomy, computational astrophysics, experimental and theoretical nuclear physics in order to provide a consistent and comprehensive answer to those questions and more.