ejaavso38.1.1

Secular Variation of the Mode Amplitude-Ratio of the Double- Mode RR Lyrae Star NSVS 5222076

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David A. Hurdis
76 Harbour Island Road, Narragansett, RI 02882

Tom Krajci
P.O. Box 1351, Cloudcroft, NM 88317

Presented at the 98th Annual Meeting of the AAVSO, November 7, 2009
Received November 9, 2009; revised November 19, 2009; accepted November 19, 2009

Abstract
In 2008, a campaign of time-series observations (Hurdis 2009) was conducted in the V and Ibands for NSVS 5222076, a double-mode RR Lyrae (RRd) field star in Bootes. Comparison of those results with the earlier observations of Oaster, Smith, and Kinemuchi (2006) suggested that a rapid and significant decrease might be occurring in the amplitude ratio, A0/A1, of the star’s fundamental and first-overtone pulsation modes. To follow up on this interesting result, another campaign of time-series observations was conducted in 2009. We find that the amplitude ratio has indeed decreased in the V-band, from 1.93 in 2005 to 1.76 in 2008 to 1.48 in 2009.

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