Exciting Discovery Of A Rare White Dwarf Pulsar Holds The Key To Star Evolution

Astronomers have discovered a rare type of red dwarf star system, only the second of its kind to have been found. The discovery will help provide astronomers and scientists with a better understanding of stellar evolution.

Researchers with the University of Warwick have released a new study that shows a white dwarf pulsar, known as J1912-4410, that includes a white dwarf star that is rapidly spinning and lashing out at its neighbor, a red dwarf star, with powerful beams of electrical particles and radiation. The only other white dwarf pulsar known to have been found was the discovery of AR Scorpii in 2016.

"White dwarfs are the most common stellar fossils," remarked University of Warwick astronomer Ingrid Pelisoli and her colleagues in the study published in the journal Nature Astronomy. "When in binaries, they make up the dominant form of compact object binary with the Milky Way Galaxy and can offer insight into different aspects of binary formation and evolution."

The main theory that has been proposed explaining the strong magnetic fields that exist in these rare binary systems is the "dynamo model." This model states that white dwarfs have dynamos, or electrical generators, in their core, just as Earth does, but many times more powerful. In order to test the dynamo model theory, however, scientists needed to search for other white dwarf pulsars in order to see if the theory held up.

The newly found white dwarf pulsar lies 773 light-years from Earth, and is spinning at a rate 300 times faster than our home planet. The white dwarf is similar in size to Earth, but has a mass that is at least as large as the Sun. This translates into a teaspoon of white dwarf material equaling around 15 tons. Being white dwarfs begin their lives at extraordinarily hot temperatures before cooling down, the low temperatures of J1912-4410 indicate an advanced age.

Dr. Pelisoli added that the origins of magnetic fields are a looming question in many fields of astronomy, and is particularly true for white dwarfs. She explained, "The magnetic fields in white dwarfs can be more than a million times stronger than the magnetic field of the Sun, and the dynamo model helps to explain why. The discovery of J1912-4410 provided a critical step forward in this field."

The team said there were other predictions made by the dynamo model and were confirmed by the discovery of J1912-4410. Some of those predictions included the white dwarf being cooler than 13,000 K, spinning on its axis once every five minutes, and the gravitational pull of the white dwarf having a strong effect on its companion red dwarf star.

"This research is an excellent demonstration that science works," exclaimed Dr. Pelisoli, "we can make predictions and put them to test, and that is how any science progresses."