Periodicity Analysis of the Semiregular Variable Star EV Aquarii
Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4, Canada
Arne A. Henden
AAVSO, 49 Bay State Road, Cambridge, MA 02138
Received May 5, 2011; revised September 8, 2011; accepted September 13, 2011
EV Aquarii is a variable star which was formerly misclassified as a cataclysmic variable, but photometric observations and colour indices have since indicated that it is most likely a semiregular M giant. The authors of this paper have used self-correlation analysis and Fourier analysis to determine the variability profile of the star. Data from the AAVSO International Database, the All-Sky Automated Survey, The Amateur Sky Survey, and co-author Arne Henden were used. The period of variation has been found to be 123.6 days ± 2.1 days. The amplitude of this variation is not constant; it changes with time between approximately 0.4 and 1.0 magnitude. There were no indications of a longer secondary period, though there has been observed an instance of a transient period of variation on a shorter timescale of about 40 days. There was no evidence found of periodic variation of the color differences.