Discovery of eleven new ZZ Ceti stars ^*

¹ Instituto de Física, Universidade Federal do Rio Grande do Sul, 91501-900 Porto-Alegre, RS, Brazil e-mail: barbara@if.ufrgs.br
² Department of Astronomy and McDonald Observatory, University of Texas, Austin, TX 78712, USA
³ Institut für Theoretische Physik und Astrophysik, Universität Kiel, 24098 Kiel, Germany
⁴ Sloan Digital Sky Survey, Apache Pt. Observatory, PO Box 59, Sunspot, NM 88349, USA
⁵ Steward Observatory, University of Arizona 933 N. Cherry Ave. Tucson, AZ 85721, USA
⁶ Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
⁷ Hamburger Sternwarte, Gojensbergweg 112, 21029 Hamburg, Germany

Received: 24 May 2005
Accepted: 1 December 2005

Abstract

We report the discovery of eleven new ZZ Cetis using telescopes at OPD (Observatório do Pico dos Dias/LNA) in Brazil, the 4.1 m SOAR (Southern Astrophysical Research) telescope at Cerro Pachon, Chile, and the 2.1 m Otto Struve telescope at McDonald observatory. The candidates were selected from the SDSS (Sloan Digital Sky Survey) and SPY (ESO SN Ia progenitor survey), based on their obtained from optical spectra fitting. This selection criterion yields the highest success rate of detecting new ZZ Cetis, above 90% in the range from 12 000 to 11 000 K. We also report on a DA not observed to vary, with a placing the star close to the blue edge of the instability strip. Among our new pulsators, one is slightly cooler than this star for which pulsations were not detected. Our observations are an important constraint on the location of the blue edge of the ZZ Ceti instability strip.