New developments of the ZZ Ceti instability strip: The discovery of eleven new variables

TL;DR

This paper reports the discovery of eleven new ZZ Ceti variable stars and refines the understanding of the instability strip, confirming its mass dependence through new observations and lowered detection limits.

Contribution

It presents the discovery of eleven new ZZ Ceti variables and improves the characterization of the instability strip using high-sensitivity observations.

Findings

Discovered 11 new ZZ Ceti variables.

Confirmed the mass dependence of the instability strip.

Lowered detection limits near the strip edges.

Abstract

Using the SOAR 4.1 m telescope, we report on the discovery of low amplitude pulsations for three stars previously reported as Not-Observed-to-Vary (NOV) by Mukadam et al. (2004) and Mullally et al. (2005), which are inside the ZZ Ceti instability strip. With the two pulsators discovered by Castanheira et al. (2007), we have now found variability in a total of five stars previously reported as NOVs. We also report the variability of eight new pulsating stars, not previously observed, bringing the total number of known ZZ Ceti stars to 148. In addition, we lowered the detection limit for ten NOVs located near the edges of the ZZ Ceti instability strip. Our results are consistent with a pure mass dependent ZZ Ceti instability strip.