Observations of nonmagnetic CP stars: crossing boundaries

Abstract

Abstract.Observations of chemically peculiar (CP) stars have been conducted for decades and have revealed a variety of spectrum anomalies, most prominent among them are line enhancements of heavy elements. The earlier observations were limited to the optical region and the use of less sensitive detectors, yet are responsible for much of our current characterization of the CP star phenomenon. More recent observations embrace a wider expanse of the electromagnetic spectrum and employ more sensitive detectors that continue to unveil new levels of spectrum peculiarity. The traditional criteria used to distinguish normal from peculiar stars have become blurred, thus in some sense replacing the concept of peculiarity with one of continuity. This presentation will address the observations of the traditional nonmagnetic CP star groups over the past decade, paying particular attention to new avenues of research that have a bearing upon the interpretation of the atmospheres of CP stars and the origins of this phenomenon.