Revealing the Mysteries of Space: The Discovery of a Unique White Dwarf Pulsar

by Liam O'Connor
white dwarf pulsar

An artistic depiction of a white dwarf pulsar in a binary star arrangement. This system consists of a swiftly rotating white dwarf (depicted on the right) that propels electrons close to light speed. The high-energy electrons emit radiation bursts impacting the neighboring red dwarf star (on the left), causing pulsations across radio and X-ray wavelengths. Image credit: M. Garlick/University of Warwick/ESO.

The identification of a unique white dwarf pulsar by astronomers marks a significant advancement in our comprehension of white dwarf magnetic fields and stellar evolution. This finding lends support to the dynamo theory and hints at the existence of more such pulsars in the cosmos.

In separate studies by the University of Warwick and the Leibniz Institute for Astrophysics Potsdam (AIP), researchers uncovered this rare star system, offering fresh perspectives on stellar evolution as predicted by the dynamo model. The newly found white dwarf pulsar forms a tightly knit binary system with a red dwarf star, both of which could fit within the Sun’s dimensions. This system is only the second of its kind discovered to date.

Understanding Pulsars and White Dwarfs

White dwarfs are compact, dense remnants of stars, equal in mass to the Sun but only Earth-sized in volume. These form when a low-mass star depletes its nuclear fuel, sheds its outer layers, and undergoes significant core contraction. Known as “stellar fossils,” white dwarfs provide valuable insights into stellar evolution.

Conversely, pulsars, identified since the 1960s and numbering over 3000, are rapidly spinning, highly magnetic neutron stars. They generate strong electric fields that strip charged particles from their surface and accelerate them nearly to light speed, emitting radiation from radio to X-ray or gamma wavelengths. The rapid rotation of these stars results in short, regular bursts of radiation reaching Earth, hence their name ‘pulsar’.

A Surprising Discovery: White Dwarf Pulsars

The scientific community was taken aback when the pulsar phenomenon was first detected in a white dwarf in 2016. This occurred in the AR Scorpii star, which lacked the typical rapid rotation and strong electric fields found in conventional pulsars.

In this unique case, a white dwarf in a close binary system received particles from its neighboring red dwarf star, injected into its magnetic field. This external stimulation triggered the pulsar activity, causing the red companion star to intermittently brighten and dim dramatically. The proximity of the white and red dwarfs is such that they would collectively fit within the Sun’s size.

Exploring Magnetic Fields and the Dynamo Model

The key to this phenomenon is a strong magnetic field, the origins of which remain unknown to astrophysicists. The “dynamo model” proposes that white dwarfs contain powerful internal dynamos, akin to Earth’s but considerably stronger. To validate this model, researchers sought additional white dwarf pulsars to corroborate their hypotheses.

Recent studies published in Nature Astronomy and Astronomy & Astrophysics by an international team, including AIP, detail the newly discovered white dwarf pulsar J1912-4410 (eRASSU J191213.9-441044). Situated 773 light-years from Earth, it rotates once every five minutes, significantly faster than Earth. This pulsar, similar in size to Earth but with a mass comparable to the Sun, is so dense that a teaspoon of its material would weigh around 15 tonnes. White dwarfs initially have high temperatures, cooling over billions of years, and the low temperature of J1912-4410 suggests it is ancient.

Confirmation of the Dynamo Model

The study corroborates the presence of additional white dwarf pulsars, as previously theorized. The discovery of J1912-4410 supports several dynamo model predictions, including the coolness of ancient white dwarfs in pulsar systems, their proximity to companions for significant gravitational interactions in the past, and rapid spinning induced by mass extraction from these companions. All these factors are evident in the newly found pulsar, with the white dwarf exhibiting a cool temperature below 13,000 Kelvin, a rapid rotation frequency of about five minutes, and a strong gravitational influence on its companion.

Collaborative Research and Future Implications

One team, utilizing Gaia and WISE data, sought candidates with characteristics mirroring those of AR Scorpii. After examining several candidates, they identified one with comparable light variations. Subsequent observations using additional telescopes confirmed that this system emits radio and X-ray signals toward Earth approximately every five minutes. Another team employed the eROSITA X-ray telescope on the Spectrum-X-Gamma satellite to locate close white dwarf/red dwarf pairs. The teams combined their efforts to further analyze their discovery.

Dr. Axel Schwope from the AIP, leading the study in Astronomy & Astrophysics, expressed satisfaction with the X-ray survey findings using SRG/eROSITA. The subsequent XMM-Newton satellite observations by ESA revealed pulsations

Frequently Asked Questions (FAQs) about white dwarf pulsar

What is a white dwarf pulsar?

A white dwarf pulsar is a rare type of star system where a rapidly spinning white dwarf star, in a binary system with a red dwarf, emits bursts of radiation across various wavelengths. This phenomenon is significant in understanding stellar evolution and magnetic fields in white dwarfs.

How was the white dwarf pulsar discovered?

The white dwarf pulsar was discovered through independent studies by the University of Warwick and the Leibniz Institute for Astrophysics Potsdam (AIP). Researchers used data from Gaia, WISE, and the eROSITA X-ray telescope on the Spectrum-X-Gamma satellite to identify and confirm the presence of this unique star system.

Why is the discovery of a white dwarf pulsar important?

The discovery of a white dwarf pulsar is crucial as it provides new insights into the dynamo model of stellar evolution and helps understand the origins of strong magnetic fields in white dwarfs. It also supports the existence of more such pulsars in the universe, expanding our knowledge of celestial phenomena.

What does the discovery reveal about the dynamo model?

The discovery of the white dwarf pulsar supports the dynamo model’s predictions about the formation and evolution of stellar magnetic fields. It suggests that white dwarfs may contain powerful dynamos, or electrical generators, in their cores, which contribute to their strong magnetic fields.

What are the characteristics of the newly discovered white dwarf pulsar?

The newly discovered white dwarf pulsar, J1912-4410, is located 773 light-years from Earth and rotates once every five minutes. It is similar in size to Earth but has a mass at least as large as that of the Sun, indicating extreme density. The pulsar’s low temperature suggests that it is very old.

More about white dwarf pulsar

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ScienceGeek123 December 18, 2023 - 2:06 am

pulsar in white dwarf, amaze discovery!

InfoSeeker December 18, 2023 - 5:45 am

What’s dynamo model, clarify plz?

CosmicWonder December 18, 2023 - 9:31 am

New pulsar find, big step for science, thx!

AstroNerd December 18, 2023 - 12:41 pm

magnetic fields, important for science, yes!

CuriousMind December 18, 2023 - 6:33 pm

What is white dwarf, tell me more plz?

SkyWatcher December 18, 2023 - 8:10 pm

How far away, distant star?

StarGazer_42 December 18, 2023 - 9:30 pm

white dwarf pulsar, dynamo model explained, WOW!

AstronomyFan December 18, 2023 - 10:43 pm

cool stuff found, white dwarf pulsar, new insight


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