The problem of RR Lyrae stars with several periods

Detre, L.

doi:10.1016/0083-6656(56)90046-0

“…Detre (1956) reported that J. Balazs had identified a 153.8 day tertiary period for XZ Cyg, which, however, might also be interpreted as the beat interval between periods of approximately 57.4 and 41.6 days.…”

Section: Xz Cygni Before 1965mentioning

confidence: 99%

The Changing Blazhko Effect of XZ Cygni

Lacluyzé

¹

,

Smith

²

,

Gill

³

et al. 2004

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New CCD photometry has been obtained for the RR Lyrae variable star XZ Cygni. An analysis of old and new photometry confirms earlier results that XZ Cygni exhibits the Blazhko Effect and that its Blazhko period has changed over time. These changes in the Blazhko period are anticorrelated with observed changes in the primary period of XZ Cygni. During the first half of the twentieth century, XZ Cygni had a Blazhko period of approximately 57.4 d. Beginning in 1965, its primary period underwent a steep decline in several steps. Coincidentally, its Blazhko period increased to about 58.5 d. In 1979, the primary period suddenly increased again. After an interval in which the Blazhko Effect was small, the Blazhko Effect re-established itself, with a period of approximately 57.5 d. When its Blazhko period is near 57.5 d, XZ Cygni has also shown a tertiary period of 41.6 d. We confirm that there is evidence for a longer 3540 d period in photometry obtained during the first half of the twentieth century. XZ Cygni is compared with three other RR Lyrae stars which also appear to show changing Blazhko periods. The observed changes in the length of the Blazhko period of XZ Cygni constrain possible explanations for the Blazhko Effect. In particular, they argue against any theoretical explanation which requires that the Blazhko period be exactly equal to or directly proportional to the rotation period of the star.Comment: 45 pages, 20 figures. Accepted by A

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“…The data accumulated by indicate that the amplitude of the Blazhko Effect in XZ Cyg changed over time, but they are not sufficient to let us decide whether the 3460 d period is exactly analogous to RR Lyrae's four year period. Detre (1956) reported that J. Balazs had identified a 153.8 d tertiary period for XZ Cyg, which, however, might also be interpreted as the beat interval between periods of approximately 57.4 d and 41.6 d.…”

Section: Xz Cygni Before 1965mentioning

confidence: 99%

The Changing Blazhko Effect of XZ Cygni

Lacluyzé

¹

,

Smith

²

,

Gill

³

et al. 2002

International Astronomical Union Colloquium

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New CCD photometry has been obtained for the RR Lyrae variable star XZ Cygni. An analysis of old and new photometry confirms earlier results that XZ Cygni exhibits the Blazhko Effect and that its Blazhko period has changed over time. These changes in the Blazhko period are anticorrelated with observed changes in the primary period of XZ Cygni. During the first half of the twentieth century, XZ Cygni had a Blazhko period of approximately 57.4 d. Beginning in 1965, its primary period underwent a steep decline in several steps. Coincidentally, its Blazhko period increased to about 58.5 d. In 1979, the primary period suddenly increased again. After an interval in which the Blazhko Effect was small, the Blazhko Effect re-established itself, with a period of approximately 57.5 d. When its Blazhko period is near 57.5 d, XZ Cygni has also shown a tertiary period of 41.6 d. We confirm that there is evidence for a longer 3540 d period in photometry obtained during the first half of the twentieth century. XZ Cygni is compared with three other RR Lyrae stars which also appear to show changing Blazhko periods. The observed changes in the length of the Blazhko period of XZ Cygni constrain possible explanations for the Blazhko Effect. In particular, they argue against any theoretical explanation which requires that the Blazhko period be exactly equal to or directly proportional to the rotation period of the star.

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Detre, László

Szabados¹

2022

Biographical Encyclopedia of Astronomers

0

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The problem of RR Lyrae stars with several periods

Cited by 6 publications

References 13 publications

The Changing Blazhko Effect of XZ Cygni

The Changing Blazhko Effect of XZ Cygni

The Changing Blazhko Effect of XZ Cygni

Detre, László

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