I study explosions of stars in the Universe. Stars on the sky always look similar, but it is known that some stars suddenly experience energetic explosions. It is called "supernova". Explosions of stars eject heavy elements produced inside of the stars into interstellar space. Our Universe began only with hydrogen, helium, and small amount of lithium, and therefore, heavier elements around us (that also make our body!) are all produced inside of the stars. By studying supernovae, we can study the origin of the elements or the "roots" of ourselves.
In the last several years, I am particularly interested in the origin of precious metal such as gold and platinum. For long time, it has been believed that these elements are produced by supernovae. However, coalescence of extremely dense stars (called "neutron stars") is gaining much attention as another possibility. Coalescence of neutron stars is also known to emit strong "gravitational waves", which were actually detected in 2017 for the first time in the history. By this discovery, we are now greatly advancing our understanding on the origin of the elements.