Researchers have observed a white dwarf about 1400 light-years from Earth that is switching on and off. The observation marks the first time a white dwarf has been observed as it switches on and off. Scientists observed the object using a satellite designed to hunt for planets.
The white dwarf in question is feeding on material from an orbiting companion star. During the switching on and off that astronomers observed saw the object lose brightness within 30 minutes. Previously, that process was only seen in white dwarfs that were accreting over a period of several days or months.
The luminosity of a white dwarf is affected by the amount of material surrounding it that it is feeding on. Astronomers believe something is interfering with the material this white dwarf is accreting. When the star is “on,” the brightness is high, and the object feeds off the accretion disk surrounding it.
However, it suddenly turns “off,” resulting in a significant reduction in its brightness. Researchers believe the process causing this phenomenon is something known as magnetic gating. This happens when the magnetic field of the white dwarf spins so rapidly it creates a barrier that disrupts the material the white dwarf receives.
Magnetic gating leads to small increases in brightness on a semi-regular basis. Researchers are continuing to study the object, hoping to learn more about the physics behind accretion. Accretion is when objects such as black holes, white dwarfs, and neutron stars feed on material from neighboring stars.
White dwarfs are interesting objects. Eventually, the sun will collapse into one. The transition into a white dwarf will occur after the sun burns through its fuel, and the event is predicted to happen in about 10 billion years.