Astronomers have made a stunning discovery—the existence of a two-faced white dwarf star. This peculiar celestial object, named Janus after the two-faced Roman god, was detected by the Zwicky Transient Facility (ZTF), an instrument that diligently surveys the night sky.
Leading the team behind this groundbreaking finding is Ilaria Caiazzo, a postdoctoral scholar at Caltech. To further investigate Janus, Caiazzo utilized the CHIMERA instrument at Palomar and the HiPERCAM on the Gran Telescopio Canarias.
Observations made with the W. M. Keck Observatory unveiled the white dwarf’s extraordinary double-sided composition. One side of Janus exhibits characteristics of hydrogen, while the other side displays signs of helium. What baffles researchers is the exact cause of this puzzling phenomenon. The team has theorized that magnetic fields and variations in pressure and density of atmospheric gases may play a significant role.
Excitingly, astronomers are now keen to uncover more of these Janus-like white dwarfs through upcoming sky surveys, such as the ones conducted by the Vera C. Rubin Observatory in Chile.
Financial support for this study was provided by several institutions. These include Caltech’s Walter Burke Institute for Theoretical Physics, the European Research Council, The Leverhulme Trust, and the United Kingdom’s Science and Technology Facilities Council. Additionally, data from NASA’s Neils Gehrels Swift Observatory was crucial in determining the temperature of the white dwarf.
Caltech’s ZTF relies on funding from the National Science Foundation and its partners, namely the Heising-Simons Foundation and Caltech itself. Moreover, NASA contributes support through the Near-Earth Object Observations program, which aids in the search for near-Earth objects.
This remarkable discovery, made possible by innovative technology and tireless astronomers, has revealed the existence of a celestial Janus—an enigmatic white dwarf with two contrasting faces. As scientists continue to delve into the mysteries of the universe, who knows what other astonishing cosmic revelations await us?