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

Volume 38 number 1 (2010)

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David A. Hurdis

76 Harbour Island Road, Narragansett, RI 02882

Tom Krajci

P.O. Box 1351, Cloudcroft, NM 88317

Abstract

In 2008, a campaign of time-series observations (Hurdis 2009) was conducted in the V and I bands 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.