The first-of-its-kind white dwarf star with two distinct faces has been found by astronomers.
Burnt remnants of dead stars make up white dwarfs. After expanding into a red giant star, ejecting its outer material, and shrinking back to a blazing white-hot remnant with only the core remaining, our sun will eventually become a white dwarf in around 5 billion years.
One side of the recently found white dwarf is made of hydrogen, while the other is made of helium. The star has been given the moniker Janus after the dual-faced Roman deity of transformation. The results of the research were released in the journal Nature on July 19.
Ilaria Caiazzo, a postdoctoral scholar and research associate in astrophysics at the California Institute of Technology and the study’s primary author, claimed that the white dwarf’s surface entirely transforms from one side to the other.
White dwarfs are very dense, squeezing a mass similar to that of our sun into a space corresponding to a planet the size of Earth. Lighter elements like hydrogen and helium ascend to the top layer after the death of a star because of the enormous gravitational attraction at work. The remaining heavier elements gravitate toward the center.
When Stars Wear Masks
White dwarfs are extremely hot, and those that are the hottest have hydrogen atmospheres. The stars often have helium atmospheres as they continue to cool over time.
However, ordinary white dwarfs do not have one side of the star dominated by one element and the other by a different one.
The Zwicky Transient Facility at Caltech’s Palomar Observatory was the first to spot the peculiar star remnant. When an object occurred that rapidly varied in brightness, Caiazzo employed the equipment, which scans the heavens every night, to conduct a recent study of strongly magnetic white dwarfs.
Caiazzo and her colleagues used the HiPERCAM on the Gran Telescopio Canarias in Spain’s Canary Islands, the CHIMERA instrument at Palomar Observatory, and W.M. Maunakea’s Keck Observatory is in Hawaii.
The three observatories demonstrated Janus’ double-faced nature and composition, as well as the fact that it was rotating on its axis every 15 minutes. By dividing the white dwarf’s light into its many wavelengths using a spectrometer, astronomers were able to identify the chemical signature of hydrogen on one side and helium on the other.
With the aid of the Neil Gehrels Swift Observatory, scientists were able to calculate that the star has a searing temperature of 62,540 degrees Fahrenheit (34,726 degrees Celsius).