scholarly journals Magnetic Models Can Not Explain The Blazhko Effect in RR Lyrae Stars

2004 ◽  
Vol 193 ◽  
pp. 535-538
Author(s):  
M. Chadid ◽  
S.L.S. Shorlin ◽  
J.D. Landstreet
Keyword(s):  
Magnetic Field ◽  
Longitudinal Magnetic Field ◽  
Field Measurements ◽  
Magnetic Star ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Magnetic Field Measurements ◽  
Blazhko Effect ◽  
Bona Fide ◽  
Lyrae Stars

AbstractWe report a new series of high-precision Stokes V profiles and longitudinal magnetic field measurements of RR Lyrae, obtained with the MuSiCoS spectropolarimeter over a period of four years. These data provide no evidence whatsoever for a strong magnetic field in the photosphere of RRLyrae, which is consistent with Preston’s (1967) results, but inconsistent with apparent magnetic field detections by Babcock (1958) and Romanov et al. (1987, 1994). Following discussion of these disparate results, we conclude that RR Lyrae is a bona fide non-magnetic star, a conclusion which leads to the general falsification of models of the Blazkho effect requiring strong photospheric magnetic fields.

High-Resolution Magnetic Field Measurements of RR Lyrae Stars with SemPol

2009 ◽  
Author(s):  
E. Guggenberger ◽  
K. Kolenberg ◽  
S. C. Marsden ◽  
I. A. Waite ◽  
H. F. Henrichs ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Field Measurements ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Magnetic Field Measurements ◽  
Lyrae Stars

scholarly journals The Oblique Pulsator Model for the Blazhko Effect in RR Lyrae Stars. Theory of Amplitude Modulation I

2000 ◽  
Vol 176 ◽  
pp. 299-306 ◽  
Author(s):  
Hiromoto Shibahashi
Keyword(s):  
Magnetic Field ◽  
Symmetry Axis ◽  
Rotation Axis ◽  
Oscillation Mode ◽  
Stellar Rotation ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Quadrupole Component ◽  
Blazhko Effect ◽  
Lyrae Stars

AbstractBy assuming that RR Lyrae stars have fairly strong dipole magnetic fields with symmetry axis oblique to the rotation axis of the star, I show that the oscillation mode which would be a pure radial oscillation in absence of the magnetic field has a quadrupole component, whose symmetry axis coincides with the magnetic axis. The aspect angle of the quadrupole component changes due to the stellar rotation, and this apparent amplitude variation is interpreted as the Blazhko effect in RR Lyrae stars. It is shown that, in the case of off-axis magnetic field, phase modulation is expected. I list up some theoretical predictions based on this model, which would observationally examine this hypothesis.

scholarly journals Oblique Pulsator Model for the Blazhko Effect of RR Lyrae Stars

1995 ◽  
Vol 155 ◽  
pp. 42-43
Author(s):  
Hiromoto Shibahashi ◽  
Masao Takata
Keyword(s):  
Rotation Axis ◽  
Oscillation Mode ◽  
Stellar Rotation ◽  
Rr Lyrae Stars ◽  
Aspect Angle ◽  
Rr Lyrae ◽  
Quadrupole Component ◽  
Blazhko Effect ◽  
Apparent Variation ◽  
Lyrae Stars

AbstractBy assuming that the RR Lyrae stars have fairly strong dipole magnetic fields with the symmetry axis oblique to the rotation axis of the star, we show that the oscillation mode which would be a pure radial oscillation in absence of the magnetic field has a quadrupole component, which is axisymmetric with respect to the magnetic axis. The aspect angle of the quadrupole component changes due to the stellar rotation, and this apparent variation is interpreted as the Blazhko effect in RR Lyrae stars.

scholarly journals Measurements of the magnetic field in WD 1658+441

2013 ◽  
Vol 9 (S302) ◽  
pp. 402-403
Author(s):  
J. Ramírez Vélez ◽  
D. Hiriart ◽  
G. Valyavin ◽  
J. Valdez ◽  
F. Quiroz ◽  
...  
Keyword(s):  
Magnetic Field ◽  
White Dwarf ◽  
Longitudinal Magnetic Field ◽  
Field Measurements ◽  
Measured Variable ◽  
Preliminary Results ◽  
San Pedro ◽  
Magnetic Field Measurements ◽  
Object Of Study ◽  
The Magnetic Field

AbstractWe present the preliminary results of the measurements of longitudinal magnetic field of the massive white dwarf 1658+441. This star have an hydrogen pure atmosphere (e.g. Dupuis & Chayer, 2003). We have observed the target in a total of 18 hrs during 3 consecutive nights in June 2010 and one more in May 2011. The data was acquired with a prototypical spectropolarimeter at the San Pedro Martir Telescope in Mexico. We have tested the magnetic field measurements with our instrument using the famous Babcock's star obtaining consistent results with previous studies. For our object of study, the WD 1658+441, we have measured variable intensities of the longitudinal magnetic field of Blong = 720 kG that oscillates with an amplitude of 130 kG.

scholarly journals Blazhko effect in Cepheids and RR Lyrae stars

2013 ◽  
Vol 9 (S301) ◽  
pp. 241-248
Author(s):  
Róbert Szabó
Keyword(s):  
Time Series Data ◽  
Period Doubling ◽  
High Order ◽  
Series Data ◽  
Theoretical Point ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Starting Point ◽  
Blazhko Effect ◽  
Lyrae Stars

AbstractThe Blazhko effect is the conspicuous amplitude and phase modulation of the pulsation of RR Lyrae stars that was discovered in the early 20th century. The field of study of this mysterious modulation has recently been invigorated thanks to the space photometric missions providing long, uninterrupted, ultra-precise time-series data. In this paper I give a brief overview of the new observational findings related to the Blazhko effect, such as extreme modulations, irregular modulation cycles and additional periodicities. I argue that these findings together with dedicated ground-based efforts provide us now with a fairly complete picture and a good starting point to theoretical investigations. Indeed, new, unpredicted dynamical phenomena have been discovered in Blazhko RR Lyrae stars, such as period doubling, high-order resonances, three-mode pulsation and low-dimensional chaos. These led to the proposal of a new explanation to this century-old enigma, namely a high-order resonance between radial modes. Along these lines I present the latest efforts and advances from the theoretical point of view. Lastly, amplitude variations in Cepheids are discussed.

FIRST DETECTION OF MULTI-SHOCKS IN RR LYRAE STARS FROM ANTARCTICA: A POSSIBLE EXPLANATION OF THE BLAZHKO EFFECT

2014 ◽  
Vol 148 (5) ◽  
pp. 88 ◽  
Author(s):  
M. Chadid ◽  
J. Vernin ◽  
G. Preston ◽  
C. Zalian ◽  
C. Pouzenc ◽  
...  
Keyword(s):  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Blazhko Effect ◽  
Lyrae Stars

A New Look at the Blazhko Effect in RR Lyrae Stars with High-Quality Data from the MACHO Project

2000 ◽  
Vol 176 ◽  
pp. 291-298 ◽  
Author(s):  
D. W. Kurtz ◽  
C. Alcock ◽  
R. A. Allsman ◽  
D. Alves ◽  
T. S. Axelrod ◽  
...  
Keyword(s):  
Phase Modulation ◽  
Period Change ◽  
Quality Data ◽  
High Quality Data ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Blazhko Effect ◽  
First Results ◽  
Lyrae Stars ◽  
Better Than

AbstractWe present the first results of the analysis of 22 Blazhko stars. We find: 1) Blazhko RRab stars that are nearly pure amplitude modulators; 2) Blazhko RRab stars that have both amplitude and phase modulation; 3) A Blazhko RRab star that has an abrupt period change; 4) Proof of the Blazhko effect in RRc stars. Our data show the character of the amplitude and phase modulations of the light curves over the Blazhko cycles far better than has been previously possible.

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