T. Beers Abstract

The HK Survey of Beers, Preston, & Shectman

T. C. Beers (NOAO)


In the late 1970s, George Preston and Steve Shectman of the Carnegie Observatories began a novel effort to identify large numbers of candidate metal-poor stars in the Galaxy. By inserting an interference filter into the focal plane of a traditional objective prism plate, they demonstrated the ability to isolate roughy a 200 A band around the CaII K line, and thereby enabled a deeper prism survey (by several magnitudes) than previously possible. This work began with the Curtis Schmidt at CTIO, and was followed up for more than a decade by Beers on the Curtis Schmidt and the Burrell Schmidt at KPNO. Medium-resolution spectroscopic observations of HK survey candidates, using the CTIO 4m, CTIO 1.5m, KPNO 4m, KPNO 2.1m, and numerous other telescopes worldwide, greatly enlarged the number of known stars with [Fe/H] < -2, and set the stage for the next large survey for metal-poor stars, the Hamburg/ESO survey of Christlieb and collaborators. After briefly reviewing this history, I will highlight examples of the numerous unique objects discovered during the course of the HK survey, including the first extremely metal-poor star with measured U and Th, and other highly r process-element enhanced stars, the discovery of carbon-enhanced metal-poor stars, and stars used for exploring the apparently complex nature of the halo of the Galaxy. An update on contemporary follow-up of HK survey metal-poor candidates will be provided.