Magnetic Stars, 2011, pp. 295 – 302 First Observational Evidences for the Presence of Active, Localized Magnetic Structures in White Dwarfs Valyavin G. 1 , Wade G. A. 2 , Bagnulo S. 3 , Antonyuk K. 4 , Plachinda S. 4 , Clark D. M. 1 , Fox Machado L. 1 , Alvarez M. 1 , Lopez J. M. 1 , Hiriart D. 1 , Han I. 5 , Jeon Y.–B. 5 , Zharikov S. V. 1 , Zurita C. 6,7 , Mujica R. 8 , Shulyak D. 9 , Burlakova T. 10 1 Observatorio Astron´ omico Nacional SPM, Instituto de Astronom´ ıa, Universidad Nacional Aut´ onoma de M´ exico, Ensenada, BC, M´ exico 2 Physics Department, Royal Military College of Canada, Kingston, Ontario, Canada 3 Armagh Observatory, Northern Ireland 4 Crimean Astrophysical Observatory, Nauchny, Crimea, Ukraine 5 Korea Astronomy and Space Science Institute, Youseong–Gu, Daejeon, Republic of Korea 6 Instituto de Astrof´ ısica de Canarias, La Laguna, Tenerife, Spain 7 Departamento de Astrof´ ısica, Universidad de La Laguna, La Laguna, Tenerife, Spain 8 Instituto Nacional de Astrof´ ısica, ´ Optica y Electron´ ıca, Tonantzintla, Pueblo, M´ exico 9 Astrophysics, Georg–August–University, G¨ ottingen, Germany 10 Special Astrophysical Observatory, Nizhny Arkhyz, Russia Abstract. 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 WD1953– 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. Key words: stars: individual: WD 1953–011 – stars: magnetic fields – stars: white dwarfs 1 Introduction WD 1953–011 can be described by the low–field (B ∼ 90 kG) global and strong–field (B ∼ 500 kG) localized components, or a “magnetic spot” (Maxted et al., 2000; Valyavin et al., 2008). The presence of the spot (or “tube”, as suggested by Valyavin et al. (2008) seems strange for the isolated white dwarfs due to the fact that their convective–free envelopes make difficult the generation magnetic tubes by analogy to sunspots. Nevertheless, an examination of the idea about the magnetic activity in degenerate stars looks interesting. 295