Photometric Monitoring & Period Change in BE Lyn

Introduction

High Amplitude Delta Scuti (HADS) stars have pulsations in the radial and non-radial modes. These evolving stars are near the end of their life cycle, slowly entering the instability strip, off the main sequence on the Hertzprung-Russell (H-R) diagram.

We examined 70 new times of maxima for the HADS star BE Lyn (HD 79889) observed at the York University Observatory from 2005 to 2015, combined with data taken from literature.

Combing these new times of maxima with those found in literature an updated linear ephemeris has been calculated.  As well, the updated ephemeris was used to produce a revised O-C diagram which was analyzed using a parabolic fit, producing a more accurate rate of change for the pulsation period.

Data & Methodology

A total of 70 new times of maxima were calculated using the 60 cm (f/13) Cassegrain telescope located at the York University Observatory. Images were captured using a ST-9 CCD camera, which in conjunction with a  f/6.6 focal reducer yielded a 5′ x 5′ field of view.

Images taken during the 2005-2011 observing campaign were taken in the Johnson-Cousins I-band filter, while the 2011-2015 campaign used the Johnson-Cousins R-band filter. All exposure lengths for both filters were 50 seconds. Photometric reduction and analysis was conducted with the IRAF software package.

The differential magnitude was calculated using the comparison star GSC 3425-00544, with apparent magnitude V = 11.1.

New linear ephemeris, O-C & rate of change: (publishing soon)

BE Lyn Light Curve