Astronomers Stunned by Discovery of Two-Faced White Dwarf Star
Scientists have made a baffling discovery in the distant reaches of space, as a white dwarf star appears to have developed two distinct faces. The star, known as Janus after the Roman god of transition, is the first lone star ever recorded to possess such a bizarre characteristic. Janus, also designated as ZTF J203349.8+322901.1, is situated over 1,000 light years away in the Cygnus constellation.
Dr. Ilaria Caiazzo, an astrophysicist at Caltech who led the research, expressed amazement at the star’s appearance. “The surface of the white dwarf completely changes from one side to the other,” she said. “When I show the observations to people, they are blown away.”
Janus was initially identified by the Zwicky Transient Facility (ZTF), an instrument that diligently scans the skies from Caltech’s Palomar Observatory near San Diego. Dr. Caiazzo discovered the star during her search for white dwarfs, and it stood out due to its rapid fluctuations in brightness. Further examination revealed that Janus rotates on its axis every 15 minutes.
The star’s peculiar configuration is challenging to explain, as its exterior is composed of swirling gas, making it difficult for anything to be separated. However, one theory suggests that Janus could be experiencing a rare transition during its evolution as a white dwarf.
White dwarfs are remnants of stars that were once similar to our sun. As these stars age, they expand into red giants before shedding their outer material and forming a compact white dwarf. The intense gravitational field of a white dwarf causes heavier elements to sink toward the core, while lighter elements float to the surface, creating a two-tier atmosphere of helium below and a thin layer of hydrogen above.
When the star cools below a certain temperature, around 30,000 degrees Celsius (54,032 degrees Fahrenheit), the thicker helium layer begins to bubble, mixing with the outer hydrogen layer and causing it to vanish from view.
Dr. Caiazzo suggests that Janus may represent a white dwarf transitioning from a hydrogen-dominated surface to a helium-dominated surface. The asymmetric magnetic field of the star could be responsible for causing this lopsided transition. “If the magnetic field is stronger on one side, it could be limiting convection in the helium layer,” she explained. “On the other side, convection could be winning out, resulting in the loss of the hydrogen layer.”
The groundbreaking findings, which have been published in the journal Nature, open up new possibilities for understanding the complex mechanisms at work within white dwarf stars. Scientists will continue to study Janus and similar stars to gain further insights into their enigmatic nature.