Mining Sky Surveys for Astrophysically Interesting Variable Stars: The Cepheid Period Range

摘要

We have undertaken a project to discover new type II Cepheids in two large-area sky surveys. However, most of the candidates from the surveys differ from type II Cepheids in their amplitude and period distributions and they form a separate, cooler sequence relative to the Cepheids in a temperature-gravity plot. We refer to these objects as \u22Cepheid-lke\u22 stars. Many exhibit unstable pulsation which we illustrate with representative light curves.