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New eclipsing double white dwarf binary discovered

New eclipsing double white dwarf binary discovered
Pan-STARRS1 color giy-bands image of ZTF J2243+5242, which is the blue object in the center of the image. Credit: Burdge et al., 2020.

Astronomers from the California Institute of Technology and elsewhere report the detection of a new eclipsing detached double white dwarf binary. The system, designated ZTF J2243+5242 has an orbital period of below 10 minutes, which makes it one of the shortest-period eclipsing binaries known to date. The finding is detailed in a paper published October 7 on arXiv.org.


Astronomers are interested in finding and studying double white dwarfs (DWDs), as their mergers are believed to produce new white dwarfs with higher masses. It is assumed that some high-mass white dwarfs in the solar neighborhood could be DWD merger products.

The Zwicky Transient Facility (ZTF), using the Palomar Observatory in California, is one of the most important astronomical surveys to search for double white dwarf binary systems. So far, it has identified many close DWDs, with orbital periods under an hour.

Now, a team of astronomers led by Caltech’s Kevin B. Burdge has found a new double white dwarf from the ZTF survey. Its nature was confirmed by follow-up photometric and spectroscopic observations.

“Here, we described the discovery and characterization of ZTF J2243+5242, the second eclipsing binary known with an orbital period under 10 minutes,” the astronomers wrote in the paper.

ZTF J2243+5242 has an orbital period of 8.8 minutes and consists of two low-mass helium white dwarfs. The two components have radii of about 0.03 solar radii, while their masses are approximately 0.35 and 0.38 solar masses. The more massive white dwarf has an effective temperature of around 16,200 K and its companion is some 6,000 K hotter. The binary is estimated to be located about 6.9 million light years away from the Earth.

The authors of the paper assume that in about 400,000 years from now, the two WDs of ZTF J2243+5242 will merge, most likely to form an isolated hot subdwarf or an R Coronae Borealis star. They added that ZTF J2243+5242 is currently undergoing rapid orbital decay.

According to the study, the system is currently clearly detached, however, the two components will start interacting in approximately 320,000 years.

The scientists expect that after the merger, ZTF J2243+5242 will be one of the strongest gravitational wave sources detectable by space-based gravitational-wave detectors like ESA’s Laser Space Interferometer Antenna (LISA).

“In the era of LISA, short orbital period systems like ZTF J2243+5242 and ZTF J1539+5027 will be particularly valuable astrophysical laboratories. Because these systems fall near the peak of LISA’s sensitivity, they are detectable at large distances,” the researchers explained.

Summing up the results, Burdge’s team underlined that their study demonstrates the considerable value of photometry not just as a tool for discovering extreme systems like ZTF J2243+5242, but also a technique which can be used to precisely characterize these objects at great distances and faint apparent magnitudes.


Two new double-lined spectroscopic binary white dwarfs identified by astronomers


More information:
An 8.8 minute orbital period eclipsing

President Obama’s White House photographer breaks down his photojournalism career (video)

Pete Souza, American photojournalist and former Chief Official White House Photographer for U.S. Presidents Barack Obama and Ronald Reagan, takes us through his illustrious career. From capturing Reagan’s reaction to Space Shuttle Challenger’s explosion to photographing President Obama’s Cabinet in the situation room during the raid on Bin Laden, Pete breaks down some of his most iconic images. ‘The Way I See It’ is in theaters now and will be broadcasted on MSNBC beginning this Friday, October 16th. See the complete video here.

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3,500-pound great white shark dubbed “Queen of the Ocean” spotted off North America’s coast

A 3,500 pound great white shark dubbed Nukumi — meaning “Queen of the Ocean” — has been spotted off the coast of Nova Scotia. The massive 50-year-old shark was tagged and released by Ocearch, a research and exploring team that hopes its latest trip out to sea provides new clues to unravel the mysteries of great whites.

“When you see these big females like that that have scars from decades over their lives and multiple mating cycles, you can really kinda see the story of their life unfolding across all the blotches and healed wounds on their body,” team leader Chris Fischer told CBS News’ Jeff Glor. “It really hits you differently thank you would think.”   

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A 50-year-old, 3,500-pound shark nicknamed Nukumi, meaning “Queen of the Ocean.”

CBS News/Ocearch


Tagging Nukumi, one of the largest great white sharks ever seen, was the crowning achievement of Ocearch’s month-long trip off the North American coast that had them running from storms for 21 days in the middle of an unprecedented Atlantic hurricane season. 

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Tagging Nukumi, one of the largest great white sharks ever seen, was the crowning achievement of Ocearch’s month-long trip.

CBS News / Ocearch


At the end, Ocearch was successfully able to sample and release a total of eight great white sharks, including the so-called “Queen of the Ocean.” 

Fischer explained that tracking Nukumi comes with a “great opportunity” to show the researchers “where the Atlantic Canada white shark gives birth” — something that has never been witnessed before. 

Along with gathering more information on their birth, Ocearch’s goal is to learn more about the apex predators that keep the ocean in balance

“If they thrive, the system thrives,” Fischer explained. “The white shark is the balance keeper, and the path to abundance goes through them.”

Without white sharks in the ocean, fish supplies that humans depend on could be wiped out by overpopulations of seals and squids. 

“If we understand their lives, we can help them thrive,” he said. 

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They try to keep each shark out of the water for no more than 15 minutes, during which the animal is sustained by a rush of seawater.

CBS News / Ocearch


Ocearch’s satellite tags allow researchers to track sharks for five years. The practice of tagging involves hooking the shark with a smaller boat, then gliding it onto a large lift, and allowing scientists to take blood samples and attach a tag to the dorsal fin, which they say does not cause pain due to a lack of blood and nerve connections. They try to keep each shark out of the water for no more than 15 minutes, during which the animal is sustained by a rush of seawater.

Fischer defended the team’s methods, which have been criticized for being too invasive. 

“When you look at the blood data and the stress data, it doesn’t indicate that,” he said.

He said Ocearch’s mission is “orders of magnitude greater” than anything previously done in white shark research, which he

DOJ sues Yale University for discriminating against white, Asian applicants

Of over 13,000 students at Yale in 2019, less than 8 percent were Black. The suit was called ‘baseless.’

The Department of Justice, headed by Attorney General Bill Barr, has sued Yale University for allegedly discriminating against white and Asian applicants.

“All persons who apply for admission to colleges and universities should expect and know that they will be judged by their character, talents and achievements and not the color of their skin,” Assistant Attorney General Eric Dreiband for the Civil Rights Division said in a statement. “To do otherwise is to permit our institutions to foster stereotypes, bitterness and division.”

Trees bloom on the campus of Yale University in New Haven, Connecticut. The Department of Justice, headed by Attorney General Bill Barr, has sued Yale for allegedly discriminating against white and Asian applicants. (Photo by Christopher Capozziello/Getty Images)
Trees bloom on the campus of Yale University in New Haven, Connecticut. The Department of Justice, headed by Attorney General Bill Barr, has sued Yale for allegedly discriminating against white and Asian applicants. (Photo by Christopher Capozziello/Getty Images)

The lawsuit is the result of a two-year investigation into claims by Asian American groups that their race was a factor in hundreds of admissions decisions. The investigation stemmed from a 2016 complaint against Yale and several other Ivy League schools, including Brown University and Dartmouth College.

The Department of Justice is alleging that Yale’s admissions process violates Title VI the 1964 Civil Rights Act.

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The complaint alleges that the university violates the act by “subjecting domestic, non-transfer Asian and white applicants to Yale College to unlawful discrimination on the ground of race.”

The investigation alleges that Asian and white students have “one-tenth to one-fourth of the likelihood of admission as African American applications with comparable academic credentials.”

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In mid-August, the Department of Justice demanded that Yale stop using race or national origin in its 2020-2021 admissions cycle. The university pushed back, saying it did not plan to change its process.

Yale President Peter Salovey called the lawsuit “baseless.”

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“I want to be clear: Yale does not discriminate against applicants of any race or ethnicity,” he said in a statement. “Our admissions practices are completely fair and lawful. Yale’s admissions policies will not change as a result of the filing of this baseless lawsuit. We look forward to defending these policies in court.”

Of the more than 13,000 students at Yale in 2019, less than 8% are Black.

In 2018, the hashtag #yalewhileblack trended on Twitter after a white graduate student called campus police on a Black fellow student who had fallen asleep in a common room while studying.

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