Unveiling the Mysteries of J1912-4410: A New White Dwarf Pulsar

 White dwarfs, the compact, dense stellar remnants approximately the size of a planet, provide unique insights into star evolution and formation. These 'stellar fossils' are the end product of small-mass stars that have exhausted their fuel and shed their outer layers. An exceptional scientific breakthrough came when the University of Warwick discovered a rare pulsar emanating from a white dwarf - a phenomenon observed only twice.

Known as white dwarf pulsars, these rapidly rotating remnants, originating from a white dwarf, unleash powerful beams of electrical particles and radiation onto their neighboring red dwarf. This interaction, driven by an intense magnetic field of unknown origin, causes the system to dramatically brighten and fade at regular intervals.

Magnetic Fields and Pulsars

One prominent explanation for these intense magnetic fields is the 'dynamo model'. According to this theory, the core of a white dwarf functions as a dynamo, bearing a resemblance to Earth's dynamo, albeit significantly more potent. However, to validate this theory, scientists needed to discover additional white dwarf pulsars.

After extensive research, scientists identified a new white dwarf pulsar, J191213.72-441045.1 (or J1912-4410), marking only the second discovery following AR Scorpii (AR Sco) in 2016. Located 773 light-years away, J1912-4410 rotates 300 times faster than Earth, despite being of similar size. This white dwarf, possessing a mass equivalent to the Sun, would weigh about 15 tons per teaspoon of its material, signifying its density.

Studying the magnetic fields of white dwarfs has been an intriguing challenge in astronomical research. The dynamo model aids in comprehending why the magnetic fields in white dwarfs can be over a million times stronger than the Sun's magnetic field.

Upon examining numerous candidates, scientists discovered one with light fluctuations similar to AR Sco. Further investigations confirmed that this system emitted radio signals and X-rays toward Earth approximately every five minutes. This observation corroborated the existence of other white dwarf pulsars, as predicted by previous models.

Additional predictions of the dynamo model were validated by the discovery of J1912-4410. The white dwarfs in the pulsar system, due to their advanced age, should be cold, and their companions should be within a range where the gravitational pull of the white dwarf could have once captured mass from its partner. This process contributes to their rapid spin. All these predictions were confirmed by the newly discovered pulsar: the white dwarf has a temperature below 12,700° C, rotates once every five minutes, and exerts a strong gravitational pull on its companion.

Ref: Università di Warwick, Nature