A Progress Report on the Empirical Determination of the ZZ Ceti Instability Strip.pdf

**FULL TITLE** ASP Conference Series, Vol. **VOLUME**, **YEAR OF PUBLICATION** **NAMES OF EDITORS** A Progress Report on the Empirical Determination of the ZZ Ceti Instability Strip A. Gianninas, P. Bergeron, and G. Fontaine D´epartement de Physique, Universit´e de Montr´eal, C.P. 6128, Succ. 6 Centre-Ville, Montr´eal, Qu´ebec, Canada, H3C 3J7 0 0 2 Abstract. Although the Sloan Digital Sky Survey has permitted the discov- c ery of an increasing number of new ZZ Ceti stars, recent published analyses have e shown that there are still many relatively bright (V 17) ZZ Ceti stars waiting D to be found. We will discuss the discovery of several such objects in addition to a number of DA stars in which we detected no photometric variations. These were 1 uncovered as part of an ongoing spectroscopic survey of DA white dwarfs from the McCook Sion Catalog. By determining the atmospheric parameters of a 1 large sample of DA stars, we were able to identify objects placed within or near v the empirical boundaries of the ZZ Ceti instability strip. By establishing the 3 photometric status of these stars, we can use them in an effort to conclusively 4 0 pin down the empirical boundaries of the ZZ Ceti instability strip. 2 1 6 0 1. Ongoing Survey of the McCook Sion Catalog / h p Since the early 1990s, our group in Montreal has been carrying out a systematic - o study ai