Two-Faced Star With Helium and Hydrogen Baffles Astronomers

In a recent astronomical revelation, scientists have come across a rather peculiar two-faced star that has left them utterly perplexed.

This star, known as a white dwarf, displays an extraordinary feature – it seems to have two distinct faces. On one side, it predominantly consists of hydrogen, while on the other side, helium takes the lead. This unique characteristic has astonished astronomers, as it is the first instance of a solitary star spontaneously developing such contrasting sides.

Leading the research, Dr. Ilaria Caiazzo, an astrophysicist from Caltech, expressed her astonishment at the discovery of two-faced star. “The surface of the white dwarf completely changes from one side to the other,” she remarked. “When I show the observations to people, they are blown away.”

Two-faced star named Janus

Over 1,000 light-years away in the Cygnus constellation, an intriguing celestial entity has caught the attention of astronomers. They’ve nicknamed it Janus, drawing inspiration from the two-faced Roman god of transition.

However, in scientific circles, it goes by the formal name ZTF J203349.8+322901.1. The discovery was made using the Zwicky Transient Facility (ZTF), an advanced tool that diligently scans the night skies from Caltech’s Palomar Observatory near San Diego.

Dr. Caiazzo was in the midst of a search for white dwarfs when one particular candidate star stood out due to its rapid fluctuations in brightness. Further investigations disclosed a fascinating revelation about Janus – it was rotating on its axis every 15 minutes.

Through spectrometry measurements, which provide valuable insights into a star’s chemical makeup, scientists found that one side of Janus was predominantly composed of hydrogen, while the other side was primarily made up of helium.

The challenge for the scientists

Understanding the star’s dual nature has proven to be a perplexing challenge for scientists, given that its outer layer is composed of swirling gas. Dr. Caiazzo remarked on the difficulty of such a separation, as the components seem intertwined.

One possible explanation for this enigmatic phenomenon is that Janus might be undergoing a rare transition that has been theorized to occur during the evolution of white dwarfs.

White dwarfs are the remnants of stars that were once similar to our own sun. As these stars age, they expand into what is known as red giants.

Eventually, the outer, fluffy material of the star is blown away, and the core contracts to form a dense, fiery, and hot white dwarf. Surprisingly, these white dwarfs, despite having a mass similar to our sun, are remarkably compact and only about the size of Earth.

Star’s gravitational forces at work

The star’s powerful gravitational force is responsible for a fascinating phenomenon: heavier elements sink towards its core, while lighter elements float on top, resulting in a two-tier atmosphere. This setup consists of a helium layer below, followed by a thin layer of hydrogen, which happens to be the lightest element.

However, when the star’s temperature drops below approximately 30,000 degrees Celsius (54,032 degrees Fahrenheit), things take an interesting turn. The thicker helium layer begins to bubble, causing the outer hydrogen layer to mix in, eventually diluting and disappearing from view.

Dr. Caiazzo explained that “Not all but some white dwarfs transition from being hydrogen- to helium-dominated on their surface.”

The scientists suspect that an asymmetric magnetic field could be the driving force behind this lopsided transition. Dr. Caiazzo elaborated that if the magnetic field is stronger on one side, it might limit the bubbling of the helium layer. On the flip side, where convection could be more dominant, the hydrogen layer could be lost.