Honing in on Supernova Origins

Pasadena, CA—Type Ia supernovae are important stellar phenomena, used to measure the expansion of the universe. But astronomers know embarrassingly little about the stars they come from and how the explosions happen. New research from a team led by Harvard University and including Carnegie’s Josh Simon, Chris Burns, Nidia Morrell, and Mark Phillips examined 23 Type Ia supernovae and helped identify the formation process for at least some of them. Their work will be published in The Astrophysical Journal and is available online.

Old Star, New Trick

Pasadena, CA—The Big Bang produced lots of hydrogen and helium and a smidgen of lithium. All heavier elements found on the periodic table have been produced by stars over the last 13.7 billion years. Astronomers analyze starlight to determine the chemical makeup of stars, the origin of the elements, the ages of stars, and the evolution of galaxies and the universe. Now for the first time, astronomers have detected the presence of arsenic and selenium, neighboring elements near the middle of the periodic table, in an ancient star in the faint stellar halo that surrounds the Milky Way. Arsenic and selenium are elements at the transition from light to heavy element production, and have not been found in old stars until now.