Astronomers have recently discovered a star behaving in a way that is unlike any previously documented. This star emits a fascinating mixture of radio waves and X-rays, categorizing it as a rare member of a group of celestial objects identified just three years ago.
Positioned about 15,000 light-years away from Earth in the direction of the constellation Scutum, this star flashes every 44 minutes in both radio and X-ray emissions, with a light-year representing the distance light travels in one year—approximately 5.9 trillion miles (or 9.5 trillion kilometers).
The researchers believe it belongs to a category known as “long-period radio transients,” which are known for producing bright bursts of radio waves that can appear every few minutes or over a series of hours.
In contrast, pulsars—highly dense, rotating neutron stars formed from the remnants of massive stars—typically emit rapid radio wave pulses that can be seen from Earth as blinking lights, occurring within milliseconds to seconds.
“The nature of these objects and the mechanics behind their unusual signals remain a puzzle,” stated Ziteng Wang, an astronomer at Curtin University in Australia and lead author of a study published this week in the journal Nature.
Utilizing data from NASA’s Chandra X-ray Observatory, the Australian SKA Pathfinder (ASKAP) telescope, and other research instruments, the study revealed intriguing findings.
While the radio emissions from the newly identified star resemble those of about ten known objects in the same category, it is unique in also emitting X-rays, according to study co-author Nanda Rea, an astrophysicist from the Institute of Space Sciences in Barcelona.
The researchers proposed several theories regarding the star’s identity. It may be a magnetar—an exceptionally magnetic, spinning neutron star—or possibly a white dwarf, a compact stellar remnant orbiting a smaller companion star in what’s defined as a binary system.
“However, neither explanation fully accounts for all the observational characteristics we observed,” Wang noted.
Stars up to eight times the mass of our sun are said to ultimately transition into white dwarfs after exhausting their hydrogen fuel. This leads to gravitational collapse and expulsion of outer layers during the “red giant” phase, leaving behind a dense core the size of Earth—the white dwarf.
The emitted radio waves could potentially arise from interactions between the white dwarf and the hypothesized companion star, according to the researchers.
“The brightness of this object fluctuates significantly. We detected no radio emissions from it before November 2023. However, by February 2024, it exhibited an unprecedented brightness. Fewer than 30 objects have ever reached such brilliance in radio waves. Notably, we also observed X-ray pulses from the object at that time, though it is now detectable in radio waves at a much fainter level,” Wang explained.
Wang expressed excitement over observing this new type of stellar behavior.
“The detection of X-rays came from NASA’s Chandra space telescope—what a fortunate coincidence! The telescope was focused on a different target but happened to capture this source during its exceptionally bright phase, which is incredibly rare—almost like finding a needle in a haystack,” Wang remarked.
