Evan N. Kirby
Assistant Professor of Astronomy
Research InterestsThe origin of the elementsChemical evolution of dwarf galaxiesThe build-up of stellar metals over cosmic timeThe oldest, most metal-poor stars in the Universe
The universe began with hydrogen, helium, and a tiny bit of lithium. Every other element was made inside of stars. As time elapsed, stars manufactured more and more of these heavier elements. Different types of stars created different amounts of each element. The ratio of two elements, such as magnesium to iron, indicates the types of stars that were contributing to the rise of the elements.
Prof. Kirby uses stellar spectroscopy to measure the elemental compositions of stars, and he uses those measurements to infer which types of stars existed long ago and how quickly those stars were forming and dying. His favorite type of galaxy is a dwarf galaxy. Dwarf galaxies are near enough to be studied in detail and simple enough to make straightforward interpretations about their elemental evolution. For this work, Prof. Kirby uses a variety of spectrographs on the Keck telescopes in Hawaii.
He also is involved in designing the Galactic Archaeology survey for the Prime Focus Spectrograph on the Subaru telescope. Furthermore, he is planning a Stellar Isotope Survey at Caltech (SISC). SISC will measure not just the amount of elements in stars in our galaxy but also how those elements are distributed among their constituent isotopes. SISC will be one of the most detailed surveys of galactic chemical evolution.