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Title: WHAT IS THE DIFFERENCE? BLAZHKO AND NON-BLAZHKO RRab STARS AND THE SPECIAL CASE OF V123 IN M3

In an extended photometric campaign of RR Lyrae variables of the globular cluster M3, an aberrant-light-curve, non-Blazhko RRab star, V123, was detected. Based on its brightness, colors and radial-velocity curve, V123 is a bona fide member of M3. The light curve of V123 exhibits neither a bump preceding the light minimum, nor a hump on the rising branch, and has a longer than normal rise time, with a convex shape. A similar shape characterizes the mean light curves of some large-modulation-amplitude Blazhko stars, but none of the regular RRab variables with similar pulsation periods. This peculiar object thus mimics Blazhko variables without showing any evidence of periodic amplitude and/or phase modulation. We cannot find any fully convincing answer to the peculiar behavior of V123, however, the phenomenon raises again the possibility that rotation and aspect angle might play a role in the explanation of the Blazhko phenomenon, and that some source of inhomogeneity (magnetic field, chemical inhomogeneity) deforms the radial pulsation of Blazhko stars during the modulation.
Authors:
; ; ; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ; ;  [8]
  1. Konkoly Observatory, H-1525 Budapest, P.O. Box 67 (Hungary)
  2. Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago (Chile)
  3. Department of Astronomy, Indiana University Bloomington, Swain West 319, 727 E. 3rd Street, Bloomington, IN 47405 (United States)
  4. Harvard-Smithsonian Center for Astrophysics. Astronomy, 60 Garden Street MS-42, Cambridge, MA 02138 (United States)
  5. Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan 200D, B-3001 Heverlee (Belgium)
  6. Department of Experimental Physics and Astronomical Observatory, University of Szeged, 6720 Szeged, Dóm tér 9 (Hungary)
  7. National Optical Astronomy Observatories, Tucson, AZ 85726-6732 (United States)
  8. The Smithsonian Astrophysical Observatory, Cambridge, MA 02138 (United States)
Publication Date:
OSTI Identifier:
22364118
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 778; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMPLITUDES; ASTRONOMY; ASTROPHYSICS; BRIGHTNESS; COLOR; DIAGRAMS; MODULATION; OSCILLATIONS; PERIODICITY; PULSATIONS; PULSE RISE TIME; RADIAL VELOCITY; ROTATION; STAR CLUSTERS; VARIABLE STARS; VISIBLE RADIATION