The Nainital-Cape Survey

III. A search for pulsational variability in chemically peculiar stars

¹ Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak, Nainital, India e-mail: santosh@aries.res.in
² Université de Nice Sophia Antipolis, Observatoire de la Côte d'Azur, Nice, France e-mail: david.mary@unice.fr; camille.billaud@wanadoo.fr
³ School of Studies in Physics and Astrophysics, Pt. Ravishankar Shukla University, Raipur, India e-mail: nkchakradhari@gmail.com

Received: 24 April 2009
Accepted: 2 September 2009

Abstract

Context. The Nainital-Cape survey is a dedicated research programme to search for and study the pulsational variability in chemically peculiar stars in the Northern Hemisphere.

Aims. The aim of the survey is to search for such chemically peculiar stars that are pulsationally unstable.

Methods. The observations of the sample stars were carried out in high-speed photometric mode using a three-channel fast photometer attached to the 1.04-m Sampurnanand telescope at ARIES.

Results. The new photometric observations confirmed that the pulsational period of star HD 25515 is 2.78-hrs. The repeated time-series observations of HD 113878 and HD 118660 revealed that previously known frequencies are indeed present in the new data sets. We have estimated the distances, absolute magnitudes, effective temperatures and luminosities of these stars. Their positions in the H-R diagram indicate that HD 25515 and HD 118660 lie near the main-sequence while HD 113878 is an evolved star. We also present a catalogue of 61 stars classified as null results, along with the corresponding 87 frequency spectra taken from 2002–2008. A statistical analysis of these null results shows, by comparison with past data, that the power of the noise in the light curves has slightly increased during the last few years.