Timothy C. Beers
Distinguished Alumnus 2017
- BS 1979, Purdue University, Physics
- BS 1979, Purdue University, Metallurgical Engineering
- AM 1980, Harvard University, Astronomy
- PhD 1983, Harvard University, Astronomy
In his early career at Harvard (1979-1983) and later as a Bantrell Postdoctoral Fellow at Caltech (1983-1986), Beers worked in the area of the structure and evolution of clusters of galaxies. This work demonstrated the importance of substructure in clusters, at a time when this was still very much an open question. He also developed dynamical models for the evolution of the “double clusters” discovered by the Einstein X-ray satellite, variations of which are still in use today. Beers also introduced the use of robust and resistant statistical techniques to the astronomical literature, now used by astronomers worldwide.
During his postdoctoral research at Caltech, and continuing to the present, Beers concentrated his efforts on the discovery and analysis of the first generations of stars in the Galaxy and the Universe. Such stars provide astronomers with their best records of the chemical composition of the Universe from the time of their formation (shortly after the Big Bang), and crucial information on the astrophysical nucleosynthesis sites of the chemical elements.
Beers continued his work in this area at Michigan State University, where he was a professor (1986-2012), retiring from that position as University Distinguished Professor, Emeritus, in order to take up the position of Director of Kitt Peak National Observatory in Tucson, Arizona, which he left to accept a chaired professorship in Astrophysics at the University of Notre Dame (2014-present). Beers is a co-PI and an Associate Director of the highly successful NSF Physics Frontier Center, JINA: Joint Institute for Nuclear Astrophysics, which brings together the work of nuclear physicists and astronomers at numerous institutions worldwide to make transformational progress on understanding of the formation of the elements, and the astrophysics of the sites in which they were produced.
Beers’ early contributions to the area of Galactic Archaeology, for which he is recognized as one of the founding fathers, were in the design and execution of the large-scale surveys required to find the exceedingly rare examples of the very oldest stars in our own Galaxy. Beers led the efforts that have resulted in the discovery of the great majority of stars known in the Galaxy with metal abundances less the [Fe/H] = -2.0 (1/100th of the solar abundance). His survey work demonstrated the existence of stars with abundances below [Fe/H] = -3.0 (1/1000th of the solar abundance), which at the time were thought not to exist in significant numbers. His work also identified the class of stars now known as carbon-enhanced metal-poor (CEMP) stars, which are now understood to be the immediate descendants of the very first stars in the Universe. The most significant results to emerge: (1) The discovery of moderate to highly r-process-element enhanced stars, including the first metal-poor stars with measured abundances of the radioactive chronometers Th and U, providing a “nuclear physics” age limit on the Universe, and crucial for understanding the astrophysical site of the r-process (which accounts for roughly half of all elements heavier than iron), and (2) Demonstration that the subset of the CEMP stars without neutron-capture overabundances (CEMP-no stars) exhibit a characteristic light-element signature that is now associated with nucleosynthesis by the very first stars born in the Universe, including the most iron-deficient star presently known, with [Fe/H] < -7.8 (almost 1/100 millionth of the solar abundance).
Beers played a major role in the execution of the next great survey of the Milky Way, which obtained medium-resolution spectroscopy of over 240,000 stars through an extension of the Sloan Digital Sky Survey, known as SEGUE: The Sloan Extension for Galactic Understanding and Exploration. Beers led the group responsible for the development, testing, and validation of the software pipeline that obtains estimates of atmospheric parameters for these stars. Beers served as Survey Scientist for the SEGUE-2 effort, which obtained an additional 200,000 medium-resolution stellar spectra. Among the results that have come from analysis of stars from SDSS/SEGUE to date: (1) Identification of the inner/outer halo structure of the Milky, including the important recognition that the most metal-deficient stars in the Galaxy are associated with the outer-halo component, (2) Photometric metallicity estimates for over one million stars, and (3) Identification of many thousands of CEMP stars used to constrain the evolution of first-generation stars in the Galaxy.
Career Highlights
- 2009 University Distinguished Professor, Michigan State University
- 2009 Humboldt Senior Research Award
- 2014 Notre Dame Chaired Professor of Astrophysics
- 2016 Fellow of the American Physical Society
- 2016 Thomson-Reuters Highly Cited Author (4th award)