Publication
Title
Observational constraints on the magnetic field of RR Lyrae stars
Author
Abstract
Context. A high percentage of the astrophysically important RR Lyrae stars show a periodic amplitude and/or phase modulation of their pulsation cycles. More than a century after its discovery, this "Blazhko effect" still lacks acceptable theoretical understanding. In one of the plausible models for explaining the phenomenon, the modulation is caused by the effects of a magnetic field. So far, the available observational data have not allowed us to either support nor rule out the presence of a magnetic field in RR Lyrae stars. Aims. We intend to determine whether RR Lyrae stars are generally characterized by the presence of a magnetic field organized on a large scale. Methods. With the help of the FORS1 instrument at the ESO VLT we performed a spectropolarimetric survey of 17 relatively bright southern RR Lyrae stars, both Blazhko stars and non-modulated stars, and determined their mean longitudinal magnetic field with a typical error bar <30G. Results. All our measurements of the mean longitudinal magnetic field resulted in null detections within 3 sigma. From our data we can set an upper limit for the strength of the dipole component of the magnetic fields of RR Lyrae stars to similar to 130 G. Because of the limitations intrinsic to the diagnostic technique, we cannot exclude the presence of higher order multipolar components. Conclusions. The outcome of this survey clarifies that the Blazhko modulation in the pulsation of RR Lyrae stars is not correlated with the presence of a strong, quasi-dipolar magnetic field.
Language
English
Source (journal)
Astronomy and astrophysics. - Berlin, 1969, currens
Publication
Berlin : Springer, 2009
ISSN
0004-6361 [print]
1432-0746 [online]
Volume/pages
498:2(2009), p. 543-550
ISI
000265868600029
Full text (Publisher's DOI)
Full text (open access)
UAntwerpen
Publication type
Subject
External links
Web of Science
Record
Identification
Creation 26.04.2018
Last edited 14.07.2021