A survey for pulsating subdwarf B stars with the Nordic Optical Telescope

TL;DR

This survey used the Nordic Optical Telescope over a decade to discover and analyze pulsating subdwarf B stars, significantly expanding the known sample and providing new physical insights.

Contribution

It is the first extensive survey to identify 20 new pulsators and improve parameters for previously known ones, enhancing understanding of these variable stars.

Findings

Discovered 20 new pulsating sdB stars.

Identified four new short period pulsators.

Provided limits on pulsation amplitudes for 285 objects.

Abstract

A search programme for pulsating subdwarf B stars was conducted with the Nordic Optical Telescope on La Palma over 59 nights between 1999 and 2009. The purpose of the programme was to significantly extend the number of rapidly pulsating sdB stars to better understand the properties of this new group of variable compact stars. Candidates were selected initially from the HS and HE surveys, but were supplemented with additional objects from other surveys. Short sequences of time-series photometry were made on the candidates to determine the presence of rapid pulsations. In total twenty new pulsators were found in this survey, most of which have already been published and some extensively studied. We present four new short period pulsators, bringing the total of such pulsators up to 49. We also give limits on pulsation amplitudes for 285 objects with no obvious periodic variations, summarise the results of the survey, and provide improved physical parameters on the composite pulsators for which only preliminary estimates were published earlier.