When you look up at a night sky, how many of the stars you see are dead? The answer might surprise you but don’t let the thought depress you - dead stars are fascinating! A star’s death may progress in one of several ways such as becoming a neuron star or even a magnetar, one of the most powerful magnets in the universe. A more common death for a star, however, results in a white dwarf. White dwarf is believed to be the last stage in a star’s life-cycle and even in this final stage, white dwarf stars can have curiously strong magnetic fields.

Magnetism of White Dwarfs

In this stage of a star’s life, the core is all that remains of the original star and it begins to cool. The core is extremely hot to begin with but has no energy source to maintain the temperature. Despite the continual heat loss, it’s estimated that about 10 percent of white dwarfs have powerful magnetic fields, stronger than the Sun’s. The magnetic personality of white dwarf stars is detectable by studying the absorption lines of the spectra. If a magnetic field exists on the dead star, the absorption line will split into three lines.The further the lines are away from the center line, the stronger the magnetic field. As the core continues to cool the lines dim and become less visible but that doesn’t mean the magnetic field disappears.

Significance

The unlikely magnetism of white dwarfs holds even more surprises for scientists. In 2012, researchers discovered a third type of chemical bonding after covalent and ionic exists near white dwarf stars. This third type of bonding called perpendicular paramagnetic bonding is impossible to recreate on Earth because it requires an extremely high magnetic field. With such a powerful magnetic field atoms could align with the field lines allowing molecules to bond. The mystery of magnetism on white dwarf stars is difficult to unravel because the length of time it takes for a white dwarf to finish cooling seems to be longer than the age of the universe. For more information on these super strong magnets in space, check out this study located in the Cornell University Library. White dwarf stars give us a glimpse into the future of our Sun. While we probably won't be there to see it, the Sun will eventually become a white dwarf as well. In the meantime, the closest white dwarf to Earth is Sirius, which is pictured above. Sirius is also the brightest star in the sky so when you look up at night you should be able to see it!