Weird white dwarf pulsar baffles boffins as its pulsating pattern changes over decades

AR Scorpii was the first white dwarf pulsar to be found

Scientists trying to crack the mystery behind the fastest-pulsating white dwarf have found that its brightness levels change over a timescale of decades.

AR Scorpii is a distant, peculiar binary star system located 380 light years away. It’s made of a collapsed white dwarf star circling its larger red dwarf companion.

It was first discovered by a group of amateur astronomers, who spotted a strange object flashing quickly. AR Sco was believed to be a single variable star, but further observations revealed it was a completely new type of system often described as a white-dwarf pulsar.

Every two minutes, the magnetized star emits a stream of particles and radiation that appears like flash beams of light, directed onto its neighboring red dwarf. It completes an orbit about every 3.5 hours, and is roughly the size of Earth but has a mass 300,000 times higher. It is estimated that if you scoop a teaspoon of AR Sco’s matter, it would weigh 15 tons.

Scientists are at a loss trying to explain how the strange star musters up the energy to pulse so frequently, and how it interacts with its companion star.

A group of researchers has attempted to study the binary system by analyzing data gathered by the Kepler Space Telescope’s K2 mission and a sky survey covering the star over a decade from 2005 to 2016. Their results have been published in The Astrophysical Journal Letters.

Peter Garnavich, co-author of the paper and a physics professor at the University of Notre Dame in South Bend, Indiana, said: “One model of this system predicts long-term variations in the way the two stars interact. It was not known what the time scale of these changes might be – whether 20 to 200 years. By looking at the K2 and archival data, we were able to show that in addition to hourly changes in the system, there are variations occurring over decades.”

The light curve of the white dwarf shows a spike every two minutes, and a puzzling variation in brightness over the orbital period.

Colin Littlefield, co-author of the paper and a researcher also at the University of Notre Dame, said they found that “12 years ago, AR Scorpii’s peak brightness came a bit later in its orbit than it does now.

“This does not solve the mystery, but it is another piece to the puzzle that is AR Scorpii.” ®

Other stories you might like

  • Cheers ransomware hits VMware ESXi systems
    Now we can say extortionware has jumped the shark

    Another ransomware strain is targeting VMware ESXi servers, which have been the focus of extortionists and other miscreants in recent months.

    ESXi, a bare-metal hypervisor used by a broad range of organizations throughout the world, has become the target of such ransomware families as LockBit, Hive, and RansomEXX. The ubiquitous use of the technology, and the size of some companies that use it has made it an efficient way for crooks to infect large numbers of virtualized systems and connected devices and equipment, according to researchers with Trend Micro.

    "ESXi is widely used in enterprise settings for server virtualization," Trend Micro noted in a write-up this week. "It is therefore a popular target for ransomware attacks … Compromising ESXi servers has been a scheme used by some notorious cybercriminal groups because it is a means to swiftly spread the ransomware to many devices."

    Continue reading
  • Twitter founder Dorsey beats hasty retweet from the board
    We'll see you around the Block

    Twitter has officially entered the post-Dorsey age: its founder and two-time CEO's board term expired Wednesday, marking the first time the social media company hasn't had him around in some capacity.

    Jack Dorsey announced his resignation as Twitter chief exec in November 2021, and passed the baton to Parag Agrawal while remaining on the board. Now that board term has ended, and Dorsey has stepped down as expected. Agrawal has taken Dorsey's board seat; Salesforce co-CEO Bret Taylor has assumed the role of Twitter's board chair. 

    In his resignation announcement, Dorsey – who co-founded and is CEO of Block (formerly Square) – said having founders leading the companies they created can be severely limiting for an organization and can serve as a single point of failure. "I believe it's critical a company can stand on its own, free of its founder's influence or direction," Dorsey said. He didn't respond to a request for further comment today. 

    Continue reading
  • Snowflake stock drops as some top customers cut usage
    You might say its valuation is melting away

    IPO darling Snowflake's share price took a beating in an already bearish market for tech stocks after filing weaker than expected financial guidance amid a slowdown in orders from some of its largest customers.

    For its first quarter of fiscal 2023, ended April 30, Snowflake's revenue grew 85 percent year-on-year to $422.4 million. The company made an operating loss of $188.8 million, albeit down from $205.6 million a year ago.

    Although surpassing revenue expectations, the cloud-based data warehousing business saw its valuation tumble 16 percent in extended trading on Wednesday. Its stock price dived from $133 apiece to $117 in after-hours trading, and today is cruising back at $127. That stumble arrived amid a general tech stock sell-off some observers said was overdue.

    Continue reading

Biting the hand that feeds IT © 1998–2022