Uncovering the Mystery: Why This ‘Teenage Vampire’ White Dwarf is Thrilling Astrophysicists

Astronomers have found an intriguing “missing link” in the life cycle of stars, particularly those like our sun. This link takes the form of a “teenage vampire” white dwarf named Gaia22ayj. Unlike what its name might suggest, it doesn’t drain blood. Instead, it’s absorbed stellar plasma from a nearby companion star. This white dwarf is about 8,150 light-years away from Earth and is behaving in exciting ways that add to our understanding of stellar evolution.

The discovery team used the Zwicky Transient Facility at California’s Palomar Observatory to observe Gaia22ayj. They scanned the night sky for rapidly changing astronomical bodies, known as transients. Gaia22ayj caught their eye because of its intense, pulsing signals, originally leading scientists to think it was two white dwarf stars rotating around each other.

However, further observations showed that this wasn’t the case. Gaia22ayj is among the most extreme pulsating objects known, with brightness ramping up by 700% in just two minutes. The findings indicate that it’s a white dwarf in a unique phase, feeding off its companion star—a process astronomers call mass transfer.

It’s fascinating to note how stars evolve based on their mass. Those with masses greater than eight times that of our sun explode in supernovae and transform into either neutron stars or black holes. In contrast, solar-mass stars undergo a gentler transformation into white dwarfs. Eventually, our sun will follow this path, puffing up into a red giant and shedding most of its mass, leaving behind a smoldering remnant.

Interestingly, about half of sun-like stars are in binary systems. If their companion star gets too close, such as in the case of Gaia22ayj, the white dwarf can gain a second chance at life by siphoning off material. This “vampiric” process allows the white dwarf to accumulate mass and energy, thus continuing its existence in a different form.

Initially, scientists were puzzled by Gaia22ayj’s light variations. Tony Rodriguez, a graduate student involved in the study, noted that the light curve did not match that of a double white dwarf binary. After extensive data collection, the team concluded that Gaia22ayj is actually a white dwarf orbiting a low-mass star, leading to the detection of its powerful magnetic field and rapid rotation.

This reminded researchers of white dwarf pulsars. Pulsars are highly magnetic and emit beams of electromagnetic radiation as they spin, almost like cosmic lighthouses. However, Gaia22ayj’s feeding process is unusual for pulsars, making its discovery even more special.

The team defined Gaia22ayj as a rare phase within the evolution of white dwarf pulsars. Rodriguez mentioned, “We have seen infant and adult systems but never one in its ‘teenage’ phase.” This phase lasts only about 40 million years, which might sound long, but is actually quite short in the life span of a star. For perspective, if a star lived as long as an average human, this phase equals roughly 107 days.

The research was substantial enough to be published in the journal Publications of the Astronomical Society of the Pacific in February. This discovery not only adds to our knowledge of white dwarfs but also raises questions about the complex lives of stars and the different paths they can take.

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