Unveiling the Two-Faced Nature of White Dwarfs: An Astronomical Breakthrough

A groundbreaking discovery in the field of astronomy has unveiled a unique characteristic of white dwarfs, the intensely hot remnants of stars akin to our sun. The intriguing revelation is that these burnt-out stellar cores can be dual-natured, with one side composed of hydrogen and the other of helium. 

Ilaria Caiazzo, a postdoctoral scholar at Caltech and the leader of the study, shares that the white dwarf's surface undergoes a complete transformation from one side to the other, a phenomenon that has left observers astounded. 

White dwarfs are the future of stars like our sun, which, after inflating into red giants and shedding their outer layers, ultimately transform into these dense, hot celestial bodies. Our sun is likely to follow this trajectory in about 5 billion years.

The white dwarf under study, nicknamed 'Janus' after the Roman deity of transition known for his two faces, was first identified by the Zwicky Transient Facility (ZTF) at Caltech's Palomar Observatory. The ZTF scans the sky nightly for such cosmic wonders.

In her pursuit of highly magnetized white dwarfs, Caiazzo came across an object exhibiting swift brightness changes. Further investigation, using the CHIMERA instrument and HiPERCAM, confirmed that Janus rotates on its axis every 15 minutes.

Additional observations made at Hawaiʻi's W. M. Keck Observatory further solidified the discovery of Janus's unique dual-faced nature. This breakthrough study has been published in the esteemed journal Nature (https://doi.org/10.1038/s41586-023-06171-9).