Utilizing ground-based telescopes, an international consortium of astronomers has observed a binary system, dubbed J0526+5934, containing at least one white dwarf. This intriguing discovery, reported in a paper published on the pre-print server arXiv on February 6, unveils a binary system comprising two white dwarfs orbiting each other at an ultra-short period.
White dwarfs, the remnants of stars that have exhausted their nuclear fuel, typically possess atmospheres composed of either pure hydrogen or pure helium. However, a minority exhibit traces of heavier elements, adding to their mystique.
Of particular interest to astronomers are double white dwarfs (DWDs), as their mergers are thought to give rise to new, more massive white dwarfs. Despite estimates suggesting a vast population of DWDs in the galaxy, only a fraction have been identified thus far.
J0526+5934 initially caught astronomers’ attention in 2019 as an extremely low-mass (ELM) white dwarf candidate. Subsequent observations revealed it to be a binary system consisting of an unseen, nearly solar-mass white dwarf primary and a visible companion weighing about 0.38 solar masses—likely a subdwarf or a low-mass white dwarf.
Fresh insights from observations led by Alberto Rebassa-Mansergas of the Technical University of Catalonia in Barcelona, Spain, shed further light on the system’s characteristics, confirming the secondary star’s white dwarf nature.
The latest observations recalibrated the visible component’s mass to a mere 0.26 solar masses, reclassifying it as an ELM white dwarf. This diminutive star boasts a radius approximately 0.065 times that of the sun and blazes with an effective temperature of 27,330 K. Its helium surface abundance and cooling age were determined to be -2.20 dex and 260 million years, respectively.
Regarding the unseen white dwarf, estimations suggest a mass of approximately 0.71 solar masses and a cooler effective temperature below 6,700 K.
With an orbital period of a mere 0.342 hours, J0526+5934 is categorized as an ultra-short period detached double white dwarf binary, marking only the fifth such system discovered to date.
Intriguingly, the researchers predict that the two white dwarfs comprising J0526+5934 will merge within approximately 3 million years, giving rise to a massive white dwarf comparable in mass to the sun—an event that promises to illuminate further our understanding of stellar evolution.