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New kilonova has astronomers rethinking what we know about gamma-ray bursts

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Enlarge / Artist’s impression of GRB 211211A. The kilonova and gamma-ray burst is on the right.

Aaron M. Geller/Northwestern/CIERA

A year ago, astronomers discovered a powerful gamma-ray burst (GRB) lasting nearly two minutes, dubbed GRB 211211A. Now that unusual event is upending the long-standing assumption that longer GRBs are the distinctive signature of a massive star going supernova. Instead, two independent teams of scientists identified the source as a so-called “kilonova,” triggered by the merger of two neutron stars, according to a new paper published in the journal Nature. Because neutron star mergers were assumed to only produce short GRBs, the discovery of a hybrid event involving a kilonova with a long GBR is quite surprising.

“This detection breaks our standard idea of gamma-ray bursts,” said co-author Eve Chase, a postdoc at Los Alamos National Laboratory. “We can no longer assume that all short-duration bursts come from neutron-star mergers, while long-duration bursts come from supernovae. We now realize that gamma-ray bursts are much harder to classify. This detection pushes our understanding of gamma-ray bursts to the limits.”

As we’ve reported previously, gamma-ray bursts are extremely high-energy explosions in distant galaxies lasting between mere milliseconds to several hours. The first gamma-ray bursts were observed in the late 1960s, thanks to the launching of the Vela satellites by the US. They were meant to detect telltale gamma-ray signatures of nuclear weapons tests in the wake of the 1963 Nuclear Test Ban Treaty with the Soviet Union. The US feared that the Soviets were conducting secret nuclear tests, violating the treaty. In July 1967, two of those satellites picked up a flash of gamma radiation that was clearly not the signature of a nuclear weapons test.

Just a couple of months ago, multiple space-based detectors picked up a powerful gamma-ray burst passing through our solar system, sending astronomers worldwide scrambling to train their telescopes on that part of the sky to collect vital data on the event and its afterglow. Dubbed GRB 221009A, it was the most powerful gamma-ray burst yet recorded and likely could be the “birth cry” of a new black hole.

There are two types of gamma-ray bursts: short and long. Classic short-term GRBs last less than two seconds, and they were previously thought to only occur from the merging of two ultra-dense objects, like binary neutron stars, producing an accompanying kilonova. Long GRBs can last anywhere from a few minutes to several hours and are thought to occur when a massive star goes supernova.

This Gemini North image, superimposed on an image taken with the Hubble Space Telescope, shows the telltale near-infrared afterglow of a kilonova produced by a long GRB.
Enlarge / This Gemini North image, superimposed on an image taken with the Hubble Space Telescope, shows the telltale near-infrared afterglow of a kilonova produced by a long GRB.

Int’l Gemini Observatory/NOIRLab/NSF/AURA/NASA/ESA

Astronomers at the Fermi and Swift telescopes simultaneously detected this latest gamma-ray burst last December and pinpointed the location in the constellation Boötes. That quick identification allowed other telescopes around the world to turn their attention to that sector, enabling them to catch the kilonova in its earliest stages. And it was remarkably nearby for a gamma-ray burst: about 1 billion light-years from Earth, compared to around 6 billion years for the average gamma-ray burst detected to date. (Light from the most distant GRB yet recorded traveled for some 13 billion years.)

“It was something we had never seen before,” said co-author Simone Dichiara, an astronomer at Penn State University and a member of the Swift team. “We knew it wasn’t associated with a supernova, the death of a massive star, because it was too close. It was a completely different kind of optical signal, one that we associate with a kilonova, the explosion triggered by colliding neutron stars.”

As two binary neutron stars begin circling into their death spiral, they send out powerful gravitational waves and strip neutron-rich matter from each other. Then the stars collide and merge, producing a hot cloud of debris that glows with light of multiple wavelengths. It’s the neutron-rich debris that astronomers believe creates a kilonova’s visible and infrared light—the glow is brighter in the infrared than in the visible spectrum, a distinctive signature of such an event that results from heavy elements in the ejecta which block visible light but lets the infrared through.

When neutron stars merge, they can produce radioactive ejecta that powers a kilonova signal. A recently observed gamma-ray burst turned out to signal a previously undetected hybrid event involving a kilonova.
Enlarge / When neutron stars merge, they can produce radioactive ejecta that powers a kilonova signal. A recently observed gamma-ray burst turned out to signal a previously undetected hybrid event involving a kilonova.

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That signature is what subsequent analysis of GRB211211A revealed. And since the subsequent decay of a neutron star merger produces heavy elements like gold and platinum, astronomers now have a new means of studying how these heavy elements form in our universe.

Several years ago, the late astrophysicist Neil Gehrels suggested that longer gamma-ray bursts could be produced by neutron star mergers. It seems only fitting that NASA’s Swift Observatory, which is named in his honor, played a key role in the discovery of GRB 211211A and the first direct evidence for that connection.

“This discovery is a clear reminder that the Universe is never fully figured out,” said co-author Jillian Rastinejad, a Ph.D. student at Northwestern University. “Astronomers often take it for granted that the origins of GRBs can be identified by how long the GRBs are, but this discovery shows us there’s still much more to understand about these amazing events.”

DOI: Nature, 2022. 10.1038/s41550-022-01819-4  (About DOIs).

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Lost and found: Codebreakers decipher 50+ letters of Mary, Queen of Scots

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Enlarge / Sample ciphertext (F38) found in the archives of the Bibliothèque Nationale de France, now attributed to Mary, Queen of Scots.

Bibliothèque nationale de France

An international team of code-breakers has successfully cracked the cipher of over 50 mysterious letters unearthed in French archives. The team discovered that the letters had been written by Mary, Queen of Scots, to trusted allies during her imprisonment in England by Queen Elizabeth I (her cousin)—and most were previously unknown to historians. The team described in a new paper published in the journal Cryptologia how they broke Mary’s cipher, then decoded and translated several of the letters. The publication coincides with the anniversary of Mary’s execution on February 8, 1587.

“This is a truly exciting discovery,” said co-author George Lasry, a computer scientist and cryptographer in Israel. “Mary, Queen of Scots, has left an extensive corpus of letters held in various archives. There was prior evidence, however, that other letters from Mary Stuart were missing from those collections, such as those referenced in other sources but not found elsewhere. The letters we have deciphered are most likely part of this lost secret correspondence.” Lasry is part of the multi-disciplinary DECRYPT Project devoted to mapping, digitizing, transcribing, and deciphering historical ciphers.

Mary sought to protect her most private letters from being intercepted and read by hostile parties. For instance, she engaged in what’s known as “letter-locking,” a common practice at the time to protect private letters from prying eyes. As we’ve reported previously, Jana Dambrogio, a conservator at MIT Libraries, coined the term “letter-locking” after discovering such letters while a fellow at the Vatican Secret Archives in 2000.

Those “locked” Vatican letters dated back to the 15th and 16th centuries, and they featured strange slits and corners that had been sliced off. Dambrogio realized that the letters had originally been folded in an ingenious manner, essentially “locked” by inserting a slice of the paper into a slit, then sealing it with wax. It would not have been possible to open the letter without ripping that slice of paper—providing evidence that the letter had been tampered with.

Portrait of Mary Stuart c. 1558–1560 at about 17 years old, painted by François Clouet.
Enlarge / Portrait of Mary Stuart c. 1558–1560 at about 17 years old, painted by François Clouet.

Public domain

Queen Elizabeth I, Catherine de Medici, Machiavelli, Galileo Galilei, John Donne, and Marie Antoinette are among the famous personages known to have employed letter-locking for their correspondence. There are hundreds of letter-locking techniques like “butterfly locks,” a simple triangular fold-and-tuck, and an ingenious method known as the “dagger-trap,” which incorporates a booby-trap disguised as another, simpler type of letter lock. Mary, Queen of Scots, used an intricate spiral letter-lock for her final letter (to King Henri III of France) on the eve of her execution for treason in February 1587. A 1574 letter from Mary also used a variant of the spiral lock.

Mary was well-trained in the art of cipher by her mother, Marie de Guise, from a very young age. The substantial collection of her letters that are housed in various archives contains tantalizing references to other missing letters. John Bossy, author of Under the Molehill: An Elizabethan Spy Story (2002), suggested that these missing letters might have been written in cipher to Mary’s extensive network of associates and allies—a network that was fatally compromised around mid-1583 by Sir Francis Walsingham (Elizabeth I’s spymaster), eventually leading to Mary’s trial and execution for treason. Like many before him, Bossy assumed those letters had been lost.

Enter Lasry and his fellow code-breaking enthusiasts: physicist and patents expert Satoshi Tomokiyo and pianist and music professor Norbert Biermann. As part of DECRYPT, they were scouring various archives for documents encrypted with ciphers, particularly documents that had not yet been attributed. They stumbled upon several collections at the Bibliothèque Nationale de France’s online archives, identifying 57 documents fully written in cipher. Other items in the collection dated from the 1520s and 1530s and were primarily concerned with “Italian affairs.” None of the text in the letters was written in clear language, so it wasn’t possible to determine who wrote them without first deciphering them.

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As Antarctic fieldwork ends, a sexual harassment reckoning looms

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Enlarge / Personal tents for staff at the Shackleton Glacier science camp, situated on the Shackleton Glacier in the Transantarctic mountains of Antarctica.

In September 2022, two months before Ph.D. student Megan Kerr was scheduled to board a military plane bound for the Antarctic ice sheet, she found herself in a conference room on Oregon State University’s campus, waiting to ask a question that had been nagging her for weeks. She sat intently through a presentation from the National Science Foundation Office of Polar Programs. Then, she raised her hand. The room full of graduate students turned in their chairs.

“This NSF report about all the sexual harassment that’s going on in the field,” she said. “What is the NSF going to be doing in the short term, also long term, about that?” Because “a lot of us are going into the field in like, two months.”

These students and about a hundred other researchers from roughly a dozen institutions had gathered at Oregon State University to kick off COLDEX, a 5-year, $25 million-dollar paleoclimatology project tasked by the NSF, the federal science agency, to find and drill a core of Earth’s oldest ice in Antarctica.

The report Kerr mentioned was the 273-page elephant in the room—a document the NSF released in late August detailing a decades-long history of pervasive sexual harassment and assault at Antarctic research stations. Almost three-quarters of women surveyed agreed that harassment was a problem, describing it as a “fact of life” on the continent. And 95 percent of women interviewed in focus groups knew someone who had experienced assault or harassment within the Antarctic program. To outsiders, the graphic details and matter-of-fact descriptions were shocking. But in the polar science community, the reaction was different.

When the report came out, “No one was surprised, other than the grad students,” Kerr said. She spoke with her principal investigators and supervisors, “and they were like, ‘Yeah, it’s been an issue for a long time.’ Okay, why is this the first time I’m hearing about it?”

Since middle school, Kerr wanted to go to Antarctica. This most recent field season, which typically takes place over the Austral summer, from mid-October to mid-February, she had finally been chosen as part of an eight-person COLDEX team to survey the ice sheet at Antarctica’s remote South Pole. She was one of two graduate students, and the only woman, on her team.

“It sucked because I was so excited for it, you know?” Kerr said. “This is a thing I wanted for years and years. And finally I got to do it, I’m getting to do it, and then I hear that oh, actually, it’s a terrible place to work if you’re a woman.”

COLDEX leadership thinks their initiative, with its unprecedented funding, unusually long timescale, and built-in commitment to diversify the polar sciences, could bring some change. But Kerr and her fellow graduate students worry the NSF response to a systemic, deeply entrenched culture problem has been surface level. They are also left wondering what the field’s path forward looks like.

Erin Pettit is an experienced polar researcher and COLDEX’s director of diversity, equity, and inclusion. Originally, her role was to guide the center in its mandate to recruit a more diverse team of researchers. But now, she’s also responsible for COLDEX’s response to the bombshell NSF report. To her, those goals are closely linked.

“Our biggest challenge actually stems from the fact that polar science started from white, male, Northern European explorations,” said Pettit. “And it is still very white and mostly male.”

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Here’s why Europe is abandoning plans to fly aboard China’s space station

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Enlarge / US Vice President Kamala Harris shakes hands with Josef Aschbacher, director general of the European Space Agency, right, during a tour of Artemis II and Artemis III mission hardware at Kennedy Space Center in Cape Canaveral, Florida, in 2022.

Alex Perez/Sipa/Bloomberg via Getty Images

Nearly six years ago the European Space Agency surprised its longtime spaceflight partners at NASA, as well as diplomatic officials at the White House, with an announcement that some of its astronauts were training alongside Chinese astronauts. The goal was to send European astronauts to China’s Tiangong space station by 2022.

“We were welcomed as colleagues and friends by the ‘taikonauts’ and the instructors,” said European astronaut Samantha Cristoforetti at the time. “Language and cultural differences are obviously a challenge, but also adds value, as we are all focused on the common goal of space exploration.”

European astronauts did not fly to the Chinese space station in 2022, however, even though China completed its construction before the end of the year. In fact, Europeans are now unlikely ever to do so, even as the Tiangong facility flies for another decade, or longer, in low-Earth orbit.

During his annual press briefing in late January, Josef Aschbacher, director general of the European Space Agency, said his focus remains on the International Space Station Partnership with NASA, Russia, Canada, and Japan. “For the moment we have neither the budgetary nor the political, let’s say, green light or intention to engage in a second space station—that is participating on the Chinese space station,” Aschbacher said.

So what changed?

Relations with US weaken

According to multiple sources who spoke with Ars on background, Aschbacher was accurate when he characterized the budget situation. ESA’s funding is less than one-third that of NASA. During its most recent budget cycle, although the space agency received an increase from member nations, it did not receive nearly all of the money it asked for. There is, accordingly, no funding to barter with China for access to Tiangong.

However, the more significant reason is probably a political one. The Americans really were blindsided by Europe’s announcement of the Chinese partnership in 2017. It came as the United States was trying to determine its own path forward with regard to the space station’s lifetime and follow-on projects. At the time, the notion that the station should fly until 2028 or even 2030 was not a universal one among US policymakers.

The Trump administration muddied these waters with a 2018 budget proposal to end the International Space Station in 2026, in order to free up funding for what would become the Artemis Moon program. This effort was quickly beaten back by the US Congress, but European officials could not help but wonder where their astronauts would go in the latter half of the 2020s if the International Space Station was gone.

Some European officials, too, were uncomfortable with the Trump administration’s talk of militarizing space. For example, in mid-2018, a key European space official, then-ArianeGroup chair Alan Charmeau, talked of how the continent must resist US efforts at space dominance. “Europe is not going to say, ‘I want to dominate the space world,'” Charmeau said. “Europe is looking for other things. Europe wants access to space. Europe wants to have their own infrastructure in space, with Galileo and Copernicus. We seek cooperation.”

At the time, this cooperation included working with China on an array of space initiatives, including astronaut training. From a political standpoint, ESA officials knew this was unwelcome by their NASA counterparts. However, it afforded them a measure of leverage with the US space agency.

Attitudes change

In the last few years, however, geopolitics and space policy have changed. Initially, almost everyone involved in space policy harbored doubts about the stability of the Trump administration’s Artemis program to return to the Moon. However, Artemis has since crystallized into a real and well-funded program. In November, when the Artemis I mission launched from Florida, European space officials proudly watched as Orion’s European-made service module propelled the vehicle out to the Moon and back to Earth.

Generally, European space officials like the Artemis program and are seeking areas for greater involvement. This is drawing them closer to NASA.

Then came Russia’s invasion of Ukraine a year ago. This has badly shaken the continent, and Russia’s war against Ukraine has strengthened ties between Europe and the United States across a number of fronts, including space.

ESA astronauts Samantha Cristoforetti and Matthias Maurer joined Chinese colleagues in Yantai, China, to take part in sea survival training, in August 2017.
Enlarge / ESA astronauts Samantha Cristoforetti and Matthias Maurer joined Chinese colleagues in Yantai, China, to take part in sea survival training, in August 2017.

ESA

Conversely, the war has driven China and Russia closer in some respects. Over the last 18 months China and Russia have been drawing up plans for an International Lunar Research Station. They intend to establish a base of operations at the Lunar South Pole, and this is correctly viewed as a Chinese-Russian alternative to the Artemis program.

Europe has been watching, and China’s passive support of Russia amid this aggression has pushed its capitals to revisit their partnerships with China. For spaceflight, this has fortified Europe’s view that it has a more stable future working with NASA and other like-minded partners in low-Earth orbit, as well as deep space. For this reason, publicly stepping back from plans to send European astronauts to China’s space station, at this time, makes sense.

Aschbacher and Europe’s space officials still want some autonomy from the United States on matters such as space launch, of course. But they understand that to realize larger programs of human spaceflight they need to pick a side. And now they have.

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