An international team using the Australian Square Kilometer Array Pathfinder (ASKAP) Telescope has identified a star system that enables the study of extreme physics: a white dwarf pulling material away from its larger companion. As the material spirals in and accretes onto the white dwarf, it produces powerful bursts of radio waves and X-rays in a cycle that repeats every 1.4 hours. In addition to being a natural laboratory, this system helped them identify the source of a class of mysterious cosmic signals.

They’re known as long-period radio transients (LPTs), coherent bursts of polarized radio emission that repeat over regular intervals. Astronomers have been searching for the source of these signals for over 20 years, and now they’ve found one that explains all of the unusual behavior observed in them. The newly identified system (ASKAP J1745−5051) is a binary consisting of a white dwarf and a red dwarf star of about 0.10 Solar masses that orbit each other with a period of just over an hour.

The team was led by PhD student Kovi Rose from the University of Sydney and the Commonwealth Scientific and Industrial Research Organization (CSIRO). He was joined by researchers from the SKA Observatory (SKAO), the Australia Telescope National Facility (ATNF), the Sydney Institute for Astronomy (SiFA), the ARC Center of Excellence for Gravitational Wave Discovery (OzGrav), the International Center for Radio Astronomy Research (ICRAR), the Dunlap Institute for Astronomy and Astrophysics, the Chinese Academy of Sciences (CAS), and multiple institutes and universities worldwide.

Artists’ impression of the white dwarf binary ASKAP J1745-5051. The smaller, denser white dwarf is accreting material from the larger but less dense red dwarf. Credit: Carl Knox (OzGrav/Swinburne) and Dr Joshua Preston Pritchard (CSIRO).

Unlike Fast Radio Bursts (FRBs), which typically last for milliseconds to a few seconds, long-period radio signals can last for minutes to hours. When astronomers first detected an LPRT in 2005, these signals were thought to be due to slow-spinning neutron stars with powerful magnetic fields (aka. magnetars). However, current astronomical models suggest that such signals would not originate in magnetar systems. An alternative explanation was that they originate in binary systems, in which a white dwarf rapidly orbits a companion star. This new discovery reinforces this latter hypothesis.

Several such signals have been detected to date, mainly in remote parts of the Milky Way. ASKAP J1745-5051 is also only the second known LRST to emit X-rays regularly, and the first one where the cause of the regularity has been confirmed. Said Rose:

For the first time, we have pinpointed the origin of these signals, confirming the source to be a ‘cataclysmic variable’, or an accreting white dwarf star. Long-period radio transients have puzzled astronomers for years. We’ve only found about a dozen, and their origins have been unclear. Now, we’ve been able to show that the source for one of these transients comes from a white dwarf actively pulling material from a companion star.

The ASKAP telescope combines a degree of coverage, resolution, and sensitivity that is unparalleled in radio astronomy, allowing astronomers to detect unusual signals that would otherwise be missed. When examining ASKAP J1745−5051, the team found that heated material drawn from the red dwarf causes it to emit X-rays, while interaction between the two stars’ magnetic fields and the charged material produces tightly beamed bursts of radio waves. This causes the radio signals to repeat at regular intervals.

*An artist’s impression of fast radio bursts in the sky above the SKA precursor ASKAP. This “fly’s eye” configuration allows the telescope to see much more of the sky at one time. Credit: OzGrav/Swinburne University of Technology*

“Some similar objects had been linked to binary systems before, but this is the first one where we can clearly see both stars and the accretion process in action,” said co-author Professor Murphy, the Head of School at the University of Sydney School of Physics and Chief Investigator at OzGrav. The discovery also provides a unique opportunity to study extreme physics by allowing scientists to test their understanding of how matter behaves in strong magnetic fields and under intense gravitational forces.

Rose also says that ASKAP J1745-5051 could act as a reference point for understanding other long-period radio transients, making it a “Rosetta Stone” for interpreting LPRTs:

These emissions are all tied to the orbital motion of the system. But interestingly, the radio and X-ray signals don’t peak at the same time, which tells us they’re being produced in different regions of the system. This system gives us a way to decode these signals. It could help us determine whether other long-period transients are more like pulsars or like white dwarf systems, acting like a stellar Rosetta stone,” said Mr Rose, referring to the archaeological object discovered in Egypt that helped translate ancient hieroglyphics.

In the near future, the team plans to combine radio, optical, and X-ray observations of ASKAP J1745-5051 to understand LRPTs better. “Each new discovery is helping us piece together the bigger picture,” said Rose. “We’re only just beginning to understand this new class of cosmic events.”

Further Reading: University of Sydney, Nature Astronomy

Los Angeles City Councilmember Nithya Raman surged past reality television personality Spencer Pratt in the city’s mayoral primary election Sunday, capping off a five-day turnaround after she fell behind to Pratt on election night.

Raman now sits in second place with Pratt in third, according to the latest vote count from the Los Angeles Registrar-Recorder. Raman had 27.1% of the votes counted so far, and Pratt had 26.7%.

Both are vying to compete in a Nov. 3 runoff against Mayor Karen Bass, who garnered 34.7% of the vote as of Sunday, and whom the Associated Press already determined has qualified for the runoff.

“We are encouraged by the latest vote count and remain grateful to the thousands of Angelenos who have powered this campaign,” Raman said in a statement issued by her campaign.

Bass campaign spokesman Alex Stack said that if Raman maintains that position, the mayor would “look forward to winning a contest against an opponent who allows encampments near schools and fights against hiring more cops, yet is MIA on saving Hollywood jobs and fighting back when ICE invades L.A.”

Mail-in ballots with a June 2 election day postmark will continue to be accepted by county election officials through Tuesday.

Pratt took an early lead over Raman on election night, but Raman’s numbers improved steadily as mail-in ballots were counted, leading political observers to begin predicting this weekend that she would eventually overtake Pratt.

Mayoral candidate Nithya Raman smiles during her election night party at Boomtown Brewery on June 2 in Los Angeles.

(Gina Ferazzi / Los Angeles Times)

“I think it’s over,” Democratic political consultant Michael Trujillo said Saturday night, after the daily vote tally showed Raman just 1 percentage point behind Pratt. “It appears Nithya will be in the runoff. Pratt doesn’t appear to be growing much more.”

Analysts say Pratt, a registered Republican, likely appealed to conservative voters, many of whom were expected to have cast their votes early. Raman, by comparison, is a progressive democratic socialist. Analysts say younger, progressive voters tend to hold onto their ballots longer than conservatives.

What’s more, many Democrats were believed to have held onto their mail-in ballots until the eleventh hour as they waited to choose between Democratic gubernatorial candidates.

“We’ve seen Nithya Raman catching up on every update,” said Paul Mitchell, vice president of the bipartisan voter data firm Political Data Inc., late Saturday.

Pratt, who came to fame as the villain on MTV’s reality show “The Hills,” turned the mayor’s race into a national story, becoming a darling of conservative media pundits on Fox News. President Trump, while not endorsing Pratt outright, offered words of support, saying he “heard he’s a big MAGA person.”

On Sunday, Pratt reminded his supporters that the ballot counting will continue in the coming weeks.

“They’re not the only ones who know where to find votes,” he wrote on X before the latest tally was released, adding a winking emoji.

Should Raman make the runoff, she would probably pose a serious threat to Bass. Despite entering the race at the filing deadline, she had a strong presence on social media. Her years on the council have also given her a deep understanding of the issues facing the city.

In a head-to-head matchup, Raman would beat Bass 32% to 28%, according to a poll of registered voters conducted last month by the UC Berkeley Institute of Governmental Studies, which was co-sponsored by The Times. The poll said 25% would choose neither or wouldn’t vote, and 15% were undecided.

During the four-month primary campaign, Raman offered withering critiques of Bass’ first term, saying the mayor failed to act with urgency on homelessness, apartment construction, street repairs and the exodus of entertainment jobs from the region.

Raman assailed Bass’ decision to negotiate an expensive package of raises with the city’s police officers, saying the deal “bankrupted the city.” And she opposed the $2.6-billion upgrade of the Convention Center, saying it would divert funds away from core city services.

Bass has pushed back on Raman’s assertions, saying she secured two consecutive years of reductions in homelessness — the first recorded in city history — and fast-tracked approval of 40,000 units of affordable housing. The mayor defended the Convention Center project, arguing it would boost tourism, while saying the police raises were needed to keep the department’s ranks from shrinking more than they already have since 2020.

Raman wasn’t endorsed by any of her colleagues on the City Council, and she has been criticized by some community leaders in her district for not paying close enough attention to their concerns.

In recent weeks, Bass has offered her own critical assessment of Raman, saying the democratic socialist struggled to work closely with others — even her own allies. Backers of the mayor accused Raman of changing her position on an array of topics, including police hiring, the city’s anti-encampment law and even who should be mayor.

Mayoral candidate Spencer Pratt speaks to the media outside an election night party at Don Antonio’s Mexican restaurant on June 2 in Los Angeles.

(Ronaldo Bolaños / Los Angeles Times)

“It is waffling,” Melina Abdullah, the co-founder of Black Lives Matter Los Angeles, said before the election about Raman’s changes on LAPD and no-camping zones. “We want to be sure we can hold her to her word. Right now we haven’t been able to.”

Bass looked like a shoo-in when she launched her reelection campaign in 2024. At that point, she received credit for moving swiftly to clear homeless encampments across the city, and to move their occupants into hotels, motels and other temporary facilities. Many of the region’s politicians, including Raman herself, sought her endorsement.

Things changed in January 2025, when Bass was more than 7,000 miles away at a diplomatic function in Ghana when the Palisades fire broke out. Many voters viewed Bass’ response to the fire as a failure of leadership. Pratt, who lost his Pacific Palisades home in the fire, blamed Bass for the loss and said it triggered his entry into the race.

Supporters of Bass portrayed Raman’s decision to jump in the race as a betrayal. Raman pushed back on that narrative, saying she provided key assistance to Bass in 2022, helping her defeat real estate developer Rick Caruso.