Secular Variation of the Mode Amplitude-Ratio of the Double-Mode RR Lyrae Star NSVS 5222076, Part II
David A. Hurdis
Presented at the 100th Spring Meeting of the AAVSO, May 21, 2011; Received June 28, 2011; revised July 15, 2011; accepted July 15, 2011
We present results from our ongoing investigation of the double-mode RR Lyrae (RRd) star, NSVS 5222076, and specifically of the long-term temporal variation of the amplitude-ratio, A0/A1, of the star’s fundamental and first-overtone pulsation modes. Our earlier paper on this subject (Hurdis and Krajci 2010) described a seemingly monotonic decrease of the amplitude-ratio in the V band, from 1.93 in 2005 to 1.76 in 2008 to 1.48 in 2009. After further observation of the star during the 2010 and 2011 observing seasons, we report that the V-band amplitude-ratio continued to decrease to 1.40 in 2010, but then increased to 1.82 in 2011. This suggests that, rather than decreasing monotonically toward a switch of dominant pulsation mode, A0/A1 may be varying in an oscillatory manner.