Astronomers Unveil Rare 'Cosmic Unicorn,' Challenging Stellar Physics

In a groundbreaking discovery, two teams of astronomers have identified a peculiar celestial object, dubbed the 'cosmic unicorn,' which is a spinning dead star with unusual properties that challenge existing theories of neutron stars and white dwarfs. The object, known as CHIME J1634+44, was simultaneously detected by researchers at the Green Bank Observatory and the Netherlands Institute for Radio Astronomy (ASTRON) using advanced radio telescopes, including the Green Bank Telescope and the LOFAR system, respectively. This finding, published in the journal Astronomy & Astrophysics on July 17, 2025, sheds light on the complex behaviors of long-period radio transients (LPTs), a newly categorized class of astronomical bodies.

The unique characteristics of CHIME J1634+44 include its status as the brightest LPT ever observed and its highly polarized radiation emissions. Team leader Fengqiu Adam Dong, a Jansky Fellow at the Green Bank Observatory, noted that the object exhibits a remarkable pattern in its pulse emissions, alternating between bursts every 14 minutes and additional pulses at intervals of 70 minutes. "We think both are real, and this is likely a system with something orbiting a neutron star," Dong explained.

Astronomers have long classified dead stars into two main categories: neutron stars and white dwarfs. Neutron stars, remnants of massive stars, collapse under gravity to form incredibly dense objects, while white dwarfs are remnants of less massive stars. CHIME J1634+44's behavior raises questions about its classification, as both teams involved in its discovery have proposed differing interpretations regarding its core. While Dong's team suggests it is likely a neutron star, the ASTRON group, led by astronomer Sanne Bloot, posits that it may be a white dwarf.

The implications of CHIME J1634+44's discovery extend beyond mere classification. Its spin appears to be accelerating, a phenomenon atypical for aging neutron stars or white dwarfs, which typically slow down as they lose energy. According to Harish Vedantham, an astronomer at ASTRON, the pulsating nature of the emissions indicates a complex relationship with a companion star or stellar remnant. This binary system could involve gravitational interactions that lead to a phenomenon known as 'spin-up.' As two stars orbit each other, they can exchange angular momentum, causing one or both to increase their rotational speed.

The unique polarization of CHIME J1634+44's radiation, which is 100% circularly polarized, suggests a novel mechanism of emission not previously observed in neutron stars or white dwarfs. The radio waves emitted twist in a corkscrew fashion, an attribute that further complicates our understanding of these stellar objects. The 'choreographed' nature of the pulse emissions, which appear in pairs after a certain number of spins, provides additional data that researchers hope will unravel the mystery behind this enigmatic body. As Vedantham remarked, "We think the pattern holds crucial information about how the companion triggers the white dwarf to emit radio waves."

This discovery is particularly significant in the context of radio astronomy, which has historically faced challenges in identifying and classifying celestial bodies emitting radio waves. The findings regarding CHIME J1634+44 not only expand the known population of LPTs but also highlight the potential for many more similar objects awaiting discovery in the cosmos. Dong concluded, "The discovery of CHIME J1634+44 expands the known population of LPTs and challenges existing models of neutron stars and white dwarfs, suggesting there may be many more such objects awaiting discovery."

As astronomers continue to monitor CHIME J1634+44, the implications of this discovery may reshape our understanding of stellar evolution and the fundamental laws governing the universe. With advanced observational tools and collaborative efforts across institutions, researchers are poised to unlock further mysteries of the cosmos, potentially leading to paradigm shifts in astrophysics.