First Observational Evidences for the Presence of Active, Localized Magnetic Structures in White Dwarfs

Valyavin, G.; Wade, G. A.; Bagnulo, S.; Antonyuk, K.; Plachinda, S.; Clark, D. M.; Fox Machado, L.; Alvarez, M.; Lopez, J. M.; Hiriart, D.; Han, I.; Jeon, Y.-B., Zharikov, S. V.; Zurita, C.; Mujica, R.; Shulyak, D.; Burlakova, T.
Bibliographical reference

Magnetic Stars. Proceedings of the International Conference, held in the Special Astrophysical Observatory of the Russian AS, August 27- September 1, 2010, Eds: I. I. Romanyuk and D. O. Kudryavtsev, p. 295-302

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2011
Number of authors
16
IAC number of authors
0
Citations
0
Refereed citations
0
Description
The magnetic white dwarf WD 1953-011 demonstrates the presence of two-component magnetic field geometry in photosphere. The geometry consists of a weak, large-scale component, and a strong, localized component (magnetic ``spot''). The localized component of the field is derived from variable due to the star's rotation circular polarization and intensity spectra. The flux from WD 1953-011 is also variable with rotation in the V-band filter. This variability can be explained by the presence of a dark spot having a magnetic nature, analogous to sunspots. Motivated by this idea, and using all available observations of WD 1953-011 we examine the possible physical relationships between the suggested dark spot and the strong-field magnetic structure recently identified on the surface of this star. Comparing the rotationally-modulated flux with the variable spectral observables related to the magnetic ``spot'' we establish their physical relationship. We discuss this result in the frame of the first observational evidences for the presence of active magnetic structures in magnetic white dwarfs.