Changing Periods of ST Puppis

Volume 43 number 2 (2015)

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Stan Walker

272 Heath Road, Waiharara, Far North 0486, New Zealand; astroman@paradise.net.nz

Neil Butterworth

24 Payne St., Mt. Louisa, Queensland 4814, Australia

Andrew Pearce

35 Viewway, Nedlands WA 6009, Australia

Abstract

ST Puppis is a reasonably bright W Virginis variable star, a Type 2 Cepheid with a record of substantial and erratic period changes—21 during the interval 1900 to 1985 with a range of magnitude from 17.4 to 19.2. It was observed as part of Variable Stars South’s Cepheid project by Butterworth in 2014 and 2015 using DSLR photometry in BGR passbands and visually by Pearce in 2015. The known period changes are shown graphically and doubtful ones examined and discarded if necessary. With its period and amplitude with a frequently changing period it is a suitable and worthwhile object for visual observing.