CDROM/AJ/V107/P0679     AH Cam (Smith+ 1994)
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AH Cam: A Metal-Rich RR Lyrae Star with the Shortest Known Blazhko Period
      Horace A. Smith, Jaymie M. Matthews, Kevin M. Lee, Jeffrey Williams, 
      N. A. Silbermann, and Michael Bolte
      <1994, AJ, 107, 679>
      =1994AJ....107..679S
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Abstract:
  Analysis of 746 new V-band observations of the RR Lyrae star AH Cam
  obtained during 1989-1992 clearly show that its light curve cannot be
  described by a single period.  In fact, at first glance, the Fourier
  spectrum of the photometry resembles that of a double-mode pulsator,
  with peaks at a fundamental period of 0.3686 d and an apparent
  secondary period of 0.2628 d.  Nevertheless, the dual-mode solution is
  a poor fit to the data.  Rather, we believe that AH Cam is a
  single-mode RR Lyrae star undergoing the Blazhko effect: periodic
  modulation of the amplitude and shape of its light curve.  What was
  originally taken to be the period of the second mode is instead the
  1-cycle/d alias of a modulation sidelobe in the Fourier spectrum.  The
  data are well described by a modulation period of just under 11 d,
  which is the shortest Blazhko period reported to date in the literature
  and confirms the earlier suggestion by Goranskii.  A low-resolution
  spectrum of AH Cam indicates that it is relatively metal rich, with
  Delta S <= 2.  Its high metallicity and short modulation period may
  provide a critical test of at least one theory for the Blazhko effect.
  Moskalik's internal resonance model makes specific predictions of the
  growth rate of the fundamental mode vs fundamental period.  AH Cam
  falls outside the regime of other known Blazhko variables and resonance
  model predicitions, but these are appropriate for metal-poor RR Lyrae
  stars.  If the theory matches the behavior of AH Cam for a metal-rich
  stellar model, this would bolster the resonance hypothesis.

File Summary:
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File Name    Lrecl    Records    Explanations
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table1.dat      15        423    1989-1990 AH Cam photometry
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Byte-by-byte Description of file: table1.dat
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   Bytes Format  Units      Label    Explanations
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   1- 8  F8.3    d          HJD     *Heliocentric Julian Date - 244000 d
   9-10  2X      ---        ---      Blank
  11-15  F5.2    mag        V       *V magnitude
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Notes for file: table1.dat
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HJD:
  Heliocentric Julian Date of midexposure.

Mag:
  Based on the scatter in the comparison-check star data, each observation
  of AH Cam is accurate to about +/- 0.025 mag.
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(End)                                             Lee Brotzman [ADS] 19-Apr-1994