![Figure caption: Simulation of the magnetic field distribution (represented by lines whose lengths are proportional to the field strength) in a “cool” white dwarf. The darker zone is a cooler region where the intense magnetic field has partially blocked th Figure caption: Simulation of the magnetic field distribution (represented by lines whose lengths are proportional to the field strength) in a “cool” white dwarf. The darker zone is a cooler region where the intense magnetic field has partially blocked th](/sites/default/files/styles/crop_square_2_2_to_320px/public/images/news/resultados141_153.jpg?itok=FQsp-bA6)
Isolated cool white dwarf stars more often have strong magnetic fields than young, hotter white dwarfs which has been a puzzle because magnetic fields are expected to decay with time but a cool surface suggests that the star is old. In addition, some white dwarfs with strong fields vary in brightness as they rotate, which has been variously attributed to surface brightness inhomogeneities similar to sunspots, chemical inhomogeneities and other magnetooptical effects. Here we describe optical observations of the brightness and magnetic field of the cool white dwarf WD1953-011 taken over
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