It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
The Trans Mountain saga is nearing its end — the larger debate will go on CBC Sat, April 20, 2024 Protesters outside an event Prime Minister Justin Trudeau is attending in Calgary, Alta., Thursday, Nov. 22, 2018. (Jeff McIntosh/The Canadian Press - image credit)
In November 2018, Prime Minister Justin Trudeau went to Calgary to speak to the chamber of commerce. A crowd gathered outside the venue and chanted, "Build that pipe."
Trudeau might have responded that he was trying to do just that — at least in regards to one pipeline. Trudeau's government had actually purchased the Trans Mountain pipeline six months earlier, with the stated purpose of ensuring its expansion could be completed.
Five and a half years later, Finance Minister Chrystia Freeland used her budget speech to celebrate the fact that the Trans Mountain expansion is nearing completion — an achievement she held out as evidence of what an "activist" federal government can accomplish.
Rising to respond a few minutes later, Conservative Leader Pierre Poilievre begged to differ. The lesson, he said, was the opposite — if the government had just gotten out of the way, a private company would have built the pipeline.
The pipeline is almost complete. The debate, obviously, is far from over.
Freeland's framing is a stretch. The federal government didn't set out to buy a pipeline — it was just willing to do so when that seemed to be the last remaining option.
But when Poilievre says the government should have gotten out of the way, he's aiming at the wrong government. It was the efforts — however futile — of British Columbia's provincial government to stymie the project that led to Kinder Morgan's decision to walk away.
And though it was suggested at the time that the federal government should have somehow compelled or cajoled the NDP government in B.C. to get out of the way, it's worth remembering that the New Democrats were dependent on a confidence-and-supply agreement with Green MLAs that committed the provincial government to using "every tool available" to block the project.
Ultimately, it was federal ownership that rendered all such tools moot.
Why an 'anti-oil' prime minister built a pipeline
On the day oil begins to flow through the new pipeline, it will finally answer the doubts raised by Poilievre's predecessor in 2019 when the Trudeau government gave the project its final approval.
"I don't believe he actually wants it built," Andrew Scheer said of the prime minister.
It takes some imagination to believe Trudeau would agree to purchase a pipeline for $4.5 billion in public funds — inviting no end of criticism from progressive rivals and environmentalists — without intending to see the expansion completed.
But you can easily understand the cognitive dissonance some were experiencing at the time. This was, after all, the prime minister described by Conservatives as the most "anti-oil" leader in Canadian history.
Scott McBride, of Nanaimo, B.C., holds a caricature of Prime Minister Justin Trudeau during a protest against the Trans Mountain pipeline expansion in Burnaby, B.C., on Saturday, March 10, 2018. (Darryl Dyck/Canadian Press)
Indigenous leaders are calling on people to raise their voices Saturday to stop a $7.4 billion pipeline expansion project that pumps oil from Canada's tar sands to the Pacific Coast. The Trans Mountain pipeline expansion by the Canadian division of Texas-based Kinder Morgan would nearly triple the flow of oil from Alberta's tar sands to the Vancouver area and dramatically increase the number of oil tankers travelling the shared waters between Canada and Washington state.
To fully understand how the Trudeau government ended up buying a pipeline, it might be necessary to review decades of inaction by countless governments against the threat of climate change and their slight efforts to reconcile meaningfully with Indigenous peoples. By the time Trudeau came to office, pipelines had taken on a symbolic value well beyond the practical.
But when Trudeau went to Calgary's Petroleum Club in 2013, he embraced two clear positions. A price on carbon emissions needed to be part of a plan to responsibly develop Canada's resources, he said, but getting Canadian resources to new markets was in the national interest and something for which the federal government should be held responsible.
(He also said that while governments can issue permits, "only communities can grant permission" — a simplistic slogan that did not survive contact with the reality Trudeau faced in 2018.)
There was a straightforward economic argument for building a new pipeline. If more Canadian oil could get to "tidewater," Canadian producers would be less dependent on the American market and would be able to charge a higher price. And by 2019 — after the government had let Northern Gateway die and Energy East had been abandoned — the Trans Mountain expansion was the only pipeline proposal left standing. Bedford Consulting Group is already projecting that CEO pay will tick higher in 2024. The Trans Mountain expansion project, shown here under construction in Abbotsford, B.C., in May 2023, is expected to add over half a million barrels per day of Canadian oil export capacity. The Trans Mountain expansion project under construction in Abbotsford, B.C., in May 2023. (Darryl Dyck/The Canadian Press)
But there may also have been a question of national unity. Albertans and their government might not be big fans of the federal government right now. It's fair to ask how much more negative the political climate might be if all efforts to build a pipeline out of the province had been thwarted.
The federal government might not recoup all of its investment when it eventually sells the newly expanded pipeline, but it's hard to put a price on holding a country together.
Politically, the purchase of the pipeline obviously didn't lead to great Liberal gains in Alberta. It also didn't save Rachel Notley's NDP government. And it may have hurt the Liberal Party with progressive voters in other provinces. But the purchase didn't lead to the sort of electoral wipeout in B.C. that Liberals might have feared at the time.
The pipeline's nearly done. Now what?
As Freeland noted in her budget speech, the Bank of Canada now expects that the start of operations for the expansion will have a measurable impact on Canada's national GDP. The Liberal government has estimated the project will generate $500 million in corporate tax revenues. (The government has pledged that all profits will be directed toward clean energy.)
At the same time, the Liberals surely will be criticized if the pipeline is sold at a loss. And they risk taking the heat for any spills or accidents that follow in the years ahead.
While his critics insisted that "climate leaders don't build pipelines" — another simplistic slogan — Trudeau positioned the project within the larger cause of transitioning to a clean economy.
"To those who want sustainable energy and a cleaner environment, know that I want that too. But in order to bridge the gap between where we are and where we're going, we need money to pay for it," he said in 2019. "It is in Canada's national interest to protect our environment and invest in tomorrow while making sure that people can feed their families today."
A prominent Alberta-based environmentalist said oil executives told him building the pipeline would better position them financially to make emissions-reducing investments.
In 2021 — the most recent year for which official data is available — Canada's oil and gas sector accounted for 189 megatonnes of greenhouse gas emissions, 28 per cent of the national total. The sector's emissions are expected to have risen in 2022. And if, a decade from now, the sector's emissions continue to rise and Canada has missed its emissions targets, Trans Mountain might be framed, fairly or not, as part of a larger failure.
If nothing else, the flow of oil through the newly expanded pipeline might only strengthen the case for getting on with the work of reducing the oil industry's emissions.
Sunday, April 14, 2024
SPACE
Brightest gamma-ray burst of all time came from the collapse of a massive star
James Webb Space Telescope observations show no sign of heavy elements
ARTIST'S VISUALIZATION OF GRB 221009A SHOWING THE NARROW RELATIVISTIC JETS — EMERGING FROM A CENTRAL BLACK HOLE — THAT GAVE RISE TO THE GRB AND THE EXPANDING REMAINS OF THE ORIGINAL STAR EJECTED VIA THE SUPERNOVA EXPLOSION. USING THE JAMES WEBB SPACE TELESCOPE, NORTHWESTERN UNIVERSITY POSTDOCTORAL FELLOW PETER BLANCHARD AND HIS TEAM DETECTED THE SUPERNOVA FOR THE FIRST TIME, CONFIRMING GRB 221009A WAS THE RESULT OF THE COLLAPSE OF A MASSIVE STAR. THE STUDY’S CO-AUTHORS ALSO FOUND THAT THE EVENT OCCURRED IN A DENSE STAR FORMING REGION OF ITS HOST GALAXY AS DEPICTED BY THE BACKGROUND NEBULA.
Now, a Northwestern-led team has confirmed that the phenomenon responsible for the historic burst — dubbed the B.O.A.T. (“brightest of all time”) — is the collapse and subsequent explosion of a massive star. The team discovered the explosion, or supernova, using NASA’s James Webb Space Telescope (JWST).
While this discovery solves one mystery, another mystery deepens.
The researchers speculated that evidence of heavy elements, such as platinum and gold, might reside within the newly uncovered supernova. The extensive search, however, did not find the signature that accompanies such elements. The origin of heavy elements in the universe continues to remain as one of astronomy’s biggest open questions.
The research will be published on Friday (April 12) in the journal Nature Astronomy.
“When we confirmed that the GRB was generated by the collapse of a massive star, that gave us the opportunity to test a hypothesis for how some of the heaviest elements in the universe are formed,” said Northwestern’s Peter Blanchard, who led the study. “We did not see signatures of these heavy elements, suggesting that extremely energetic GRBs like the B.O.A.T. do not produce these elements. That doesn’t mean that all GRBs do not produce them, but it’s a key piece of information as we continue to understand where these heavy elements come from. Future observations with JWST will determine if the B.O.A.T.’s ‘normal’ cousins produce these elements.”
Blanchard is a postdoctoral fellow at Northwestern’s Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), where he studies superluminous supernovae and GRBs. The study includes co-authors from the Center for Astrophysics | Harvard & Smithsonian; University of Utah; Penn State; University of California, Berkeley; Radbound University in the Netherlands; Space Telescope Science Institute; University of Arizona/Steward Observatory; University of California, Santa Barbara; Columbia University; Flatiron Institute; University of Greifswald and the University of Guelph.
Birth of the B.O.A.T.
When its light washed over Earth on Oct. 9, 2022, the B.O.A.T. was so bright that it saturated most of the world’s gamma-ray detectors. The powerful explosion occurred approximately 2.4 billion light-years away from Earth, in the direction of the constellation Sagitta and lasted a few hundred seconds in duration. As astronomers scrambled to observe the origin of this incredibly bright phenomenon, they were immediately hit with a sense of awe.
“As long as we have been able to detect GRBs, there is no question that this GRB is the brightest we have ever witnessed by a factor of 10 or more,” Wen-fai Fong, an associate professor of physics and astronomy at Northwestern’s Weinberg College of Arts and Sciences and member of CIERA, said at the time.
“The event produced some of the highest-energy photons ever recorded by satellites designed to detect gamma rays,” Blanchard said. “This was an event that Earth sees only once every 10,000 years. We are fortunate to live in a time when we have the technology to detect these bursts happening across the universe. It’s so exciting to observe such a rare astronomical phenomenon as the B.O.A.T. and work to understand the physics behind this exceptional event.”
A ‘normal’ supernova
Rather than observe the event immediately, Blanchard, his close collaborator Ashley Villar of Harvard University and their team wanted to view the GRB during its later phases. About six months after the GRB was initially detected, Blanchard used the JWST to examine its aftermath.
“The GRB was so bright that it obscured any potential supernova signature in the first weeks and months after the burst,” Blanchard said. “At these times, the so-called afterglow of the GRB was like the headlights of a car coming straight at you, preventing you from seeing the car itself. So, we had to wait for it to fade significantly to give us a chance of seeing the supernova.”
Blanchard used the JWST’s Near Infrared Spectrograph to observe the object’s light at infrared wavelengths. That’s when he saw the characteristic signature of elements like calcium and oxygen typically found within a supernova. Surprisingly, it wasn’t exceptionally bright — like the incredibly bright GRB that it accompanied.
“It’s not any brighter than previous supernovae,” Blanchard said. “It looks fairly normal in the context of other supernovae associated with less energetic GRBs. You might expect that the same collapsing star producing a very energetic and bright GRB would also produce a very energetic and bright supernova. But it turns out that's not the case. We have this extremely luminous GRB, but a normal supernova.”
Missing: Heavy elements
After confirming — for the first time — the presence of the supernova, Blanchard and his collaborators then searched for evidence of heavy elements within it. Currently, astrophysicists have an incomplete picture of all the mechanisms in the universe that can produce elements heavier than iron.
The primary mechanism for producing heavy elements, the rapid neutron capture process, requires a high concentration of neutrons. So far, astrophysicists have only confirmed the production of heavy elements via this process in the merger of two neutron stars, a collision detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2017. But scientists say there must be other ways to produce these elusive materials. There are simply too many heavy elements in the universe and too few neutron-star mergers.
“There is likely another source,” Blanchard said. “It takes a very long time for binary neutron stars to merge. Two stars in a binary system first have to explode to leave behind neutron stars. Then, it can take billions and billions of years for the two neutron stars to slowly get closer and closer and finally merge. But observations of very old stars indicate that parts of the universe were enriched with heavy metals before most binary neutron stars would have had time to merge. That’s pointing us to an alternative channel.”
Astrophysicists have hypothesized that heavy elements also might be produced by the collapse of a rapidly spinning, massive star — the exact type of star that generated the B.O.A.T. Using the infrared spectrum obtained by the JWST, Blanchard studied the inner layers of the supernova, where the heavy elements should be formed.
“The exploded material of the star is opaque at early times, so you can only see the outer layers,” Blanchard said. “But once it expands and cools, it becomes transparent. Then you can see the photons coming from the inner layer of the supernova.”
“Moreover, different elements absorb and emit photons at different wavelengths, depending on their atomic structure, giving each element a unique spectral signature,” Blanchard explained. “Therefore, looking at an object’s spectrum can tell us what elements are present. Upon examining the B.O.A.T.’s spectrum, we did not see any signature of heavy elements, suggesting extreme events like GRB 221009A are not primary sources. This is crucial information as we continue to try to pin down where the heaviest elements are formed.”
Why so bright?
To tease apart the light of the supernova from that of the bright afterglow that came before it, the researchers paired the JWST data with observations from the Atacama Large Millimeter/Submillimeter Array (ALMA) in Chile.
“Even several months after the burst was discovered, the afterglow was bright enough to contribute a lot of light in the JWST spectra,” said Tanmoy Laskar, an assistant professor of physics and astronomy at the University of Utah and a co-author on the study. “Combining data from the two telescopes helped us measure exactly how bright the afterglow was at the time of our JWST observations and allow us to carefully extract the spectrum of the supernova.”
Although astrophysicists have yet to uncover how a “normal” supernova and a record-breaking GRB were produced by the same collapsed star, Laskar said it might be related to the shape and structure of the relativistic jets. When rapidly spinning, massive stars collapse into black holes, they produce jets of material that launch at rates close to the speed of light. If these jets are narrow, they produce a more focused — and brighter — beam of light.
“It’s like focusing a flashlight’s beam into a narrow column, as opposed to a broad beam that washes across a whole wall,” Laskar said. “In fact, this was one of the narrowest jets seen for a gamma-ray burst so far, which gives us a hint as to why the afterglow appeared as bright as it did. There may be other factors responsible as well, a question that researchers will be studying for years to come.”
Additional clues also may come from future studies of the galaxy in which the B.O.A.T. occurred. “In addition to a spectrum of the B.O.A.T. itself, we also obtained a spectrum of its ‘host’ galaxy,” Blanchard said. “The spectrum shows signs of intense star formation, hinting that the birth environment of the original star may be different than previous events.”
Team member Yijia Li, a graduate student at Penn State, modeled the spectrum of the galaxy, finding that the B.O.A.T.’s host galaxy has the lowest metallicity, a measure of the abundance of elements heavier than hydrogen and helium, of all previous GRB host galaxies. “This is another unique aspect of the B.O.A.T. that may help explain its properties,” Li said.
The study, “JWST detection of a supernova associated with GRB 221009A without an r-process signature,” was supported by NASA (award number JWST-GO-2784) and the National Science Foundation (award numbers AST-2108676 and AST-2002577). This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope.
JWST detection of a supernova associated with GRB 221009A without an r-process signature'
ARTICLE PUBLICATION DATE
12-Apr-2024
Twinkle twinkle baby star, 'sneezes' tell us how you are
Researchers find that baby stars discharge plumes of magnetic flux during formation
KYUSHU UNIVERSITY
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THE BABY STAR AT THE CENTER SURROUNDED BY A BRIGHT DISK CALLED A PROTOSTELLAR DISK. SPIKES OF MAGNETIC FLUX, GAS, AND DUST IN BLUE. RESEARCHERS FOUND THAT THE PROTOSTELLAR DISK WILL EXPEL MAGNETIC FLUX, GAS, AND DUST—MUCH LIKE A SNEEZE—DURING A STAR'S FORMATION.
Fukuoka, Japan—Kyushu University researchers have shed new light into a critical question on how baby stars develop. Using the ALMA radio telescope in Chile, the team found that in its infancy, the protostellar disk that surrounds a baby star discharges plumes of dust, gas, and electromagnetic energy. These 'sneezes,' as the researchers describe them, release the magnetic flux within the protostellar disk, and may be a vital part of star formation. Their findings were published in The Astrophysical Journal.
Stars, including our Sun, all develop from what are called stellar nurseries, large concentrations of gas and dust that eventually condense to form a stellar core, a baby star. During this process, gas and dust form a ring around the baby star called the protostellar disk.
"These structures are perpetually penetrated by magnetic fields, which brings with it magnetic flux. However, if all this magnetic flux were retained as the star developed, it would generate magnetic fields many orders of magnitude stronger than those observed in any known protostar," explains Kazuki Tokuda of Kyushu University's Faculty of Sciences and first author of the study.
For this reason, researchers have hypothesized that there is a mechanism during star development that would remove that magnetic flux. The prevailing view was that the magnetic field gradually weakened over time as the cloud is pulled into the stellar core.
To get to the bottom of this mysterious phenomenon, the team set their sights on MC 27, a stellar nursery located approximately 450 light-years from earth. Observations were collected using the ALMA array, a collection of 66 high-precision radio telescope constructed 5,000 meters above seas level in northern Chile.
"As we analyzed our data, we found something quite unexpected. There were these 'spike-like' structures extending a few astronomical units from the protostellar disk. As we dug in deeper, we found that these were spikes of expelled magnetic flux, dust, and gas," continues Tokuda.
"This is a phenomenon called 'interchange instability' where instabilities in the magnetic field react with the different densities of the gases in the protostellar disk, resulting in an outward expelling of magnetic flux. We dubbed this a baby star's 'sneeze' as it reminded us of when we expel dust and air at high speeds."
Additionally, other spikes were observed several thousands of astronomical units away from the protostellar disk. The team hypothesized that these were indications of other 'sneezes' in the past.
The team expects their findings will improve our understanding of the intricate processes that shape the universe that continue to captivate the interest of both the astronomical community and the public.
"Similar spike-like structures have been observed in other young stars, and it's becoming a more common astronomical discovery," concludes Tokuda. "By investigating the conditions that lead to these 'sneezes' we hope to expand our understanding of how stars and planets are formed."
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For more information about this research, see "Discovery of Asymmetric Spike-like Structures of the 10 au Disk around the Very Low-luminosity Protostar Embedded in the Taurus Dense Core MC 27/L1521F with ALMA," Kazuki Tokuda, Naoto Harada, Mitsuki Omura, Tomoaki Matsumoto, Toshikazu Onishi, Kazuya Saigo, Ayumu Shoshi, Shingo Nozaki, Kengo Tachihara, Naofumi Fukaya, Yasuo Fukui, Shu-ichiro Inutsuka, and Masahiro N. Machida The Astrophysical Journalhttps://doi.org/10.3847/1538-4357/ad2f9a
About Kyushu University Founded in 1911, Kyushu University is one of Japan's leading research-oriented institutes of higher education, consistently ranking as one of the top ten Japanese universities in the Times Higher Education World University Rankings and the QS World Rankings. The university is one of the seven national universities in Japan, located in Fukuoka, on the island of Kyushu—the most southwestern of Japan’s four main islands with a population and land size slightly larger than Belgium. Kyushu U’s multiple campuses—home to around 19,000 students and 8000 faculty and staff—are located around Fukuoka City, a coastal metropolis that is frequently ranked among the world's most livable cities and historically known as Japan's gateway to Asia. Through its VISION 2030, Kyushu U will “drive social change with integrative knowledge.” By fusing the spectrum of knowledge, from the humanities and arts to engineering and medical sciences, Kyushu U will strengthen its research in the key areas of decarbonization, medicine and health, and environment and food, to tackle society’s most pressing issues.
Discovery of Asymmetric Spike-like Structures of the 10 au Disk around the Very Low-luminosity Protostar Embedded in the Taurus Dense Core MC 27/L1521F with ALMA
ARTICLE PUBLICATION DATE
11-Apr-2024
Rice’s Megan Reiter wins NSF CAREER Award to investigate planet-forming environments
RICE UNIVERSITY
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MEGAN REITER HAS WON A NATIONAL SCIENCE FOUNDATION CAREER AWARD.
CREDIT: PHOTO COURTESY OF BRANDON MARTIN/RICE UNIVERSITY.
Megan Reiter, an assistant professor of physics and astronomy at Rice University, has won a National Science Foundation (NSF) CAREER Award to investigate the influence of neighboring stars on the formation of planets.
The research funded by Reiter’s five-year, $951,446 NSF grant will shed light on a phenomenon that could significantly impact our understanding of how planets are born.
“By exploring the intricate interplay between stars, planets and their environments, we hope to clarify the key forces that shape planet formation,” Reiter said.
Observations show planets form in the gas and dust disks surrounding young stars. But as these stars age, their disks disappear, limiting the opportunity for planets to form.
One factor contributing to this disappearance is external photoevaporation, or intense radiation from a nearby, brighter star that can rapidly strip away the material in the disk.
“While we’ve observed this phenomenon in a few cases, our goal is to quantify how significant it is in the larger picture of planet formation,” Reiter said.
The research team plans to leverage a vast dataset of young star clusters. The researchers will measure the disks, the impact of starlight on them and the matter streaming away from them.
It will involve observing thousands of low-mass stars and their disks in high-mass star-forming regions, providing insights into a sample size 100 times larger than previous studies.
Key to the research is the use of sophisticated telescopic technology, including the Multi-Unit Spectroscopic Explorer, an integral field unit spectrograph on the European Southern Observatory’s Very Large Telescope. It will allow the team to separate stellar emission from the nebular background, providing clear data on external photoevaporation and quantifying the mass-loss rate.
“The data we gather will enhance our understanding of planet formation and provide valuable insights for theorists as they model planetary demographics,” Reiter said.
The project also includes an educational component to promote interest and diversity in science, technology, engineering and mathematics. It will involve teacher training and curriculum development for Houston-area schools grades kindergarten to 12th and enhancements to observational lab courses at Rice.
Reiter earned a bachelor’s degree in physics and astrophysics from the University of California, Berkeley and a Ph.D. in astronomy from the University of Arizona. She joined the Rice faculty in 2022.
The highly competitive NSF grants are awarded each year to a select cohort of about 500 early career faculty across all disciplines engaged in groundbreaking research and committed to growing their field through outreach and education.
A magnetic massive star was produced by a stellar merger
AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE (AAAS)
Shedding light on why some massive stars have magnetic fields even though these stars’ interiors layers don’t undergo convection, researchers report observational evidence that magnetic fields form in some such stars through stellar mergers. The magnetic fields of low-mass stars, like the Sun, are produced by a dynamo generated in the convective layers of the star’s interior. Massive stars – those 8 or more solar masses at formation – do not have the convective interiors required to sustain magnetic fields in this way. However, roughly 7% of massive stars have been observed to have magnetic fields, the origin of which is poorly understood. Several mechanisms have been proposed. One possibility is that the magnetic fields could arise through mixing of stellar material, such as during a stellar merger. Here, Abigail Frost and colleagues present multi-epoch interferometric and spectroscopic observations of HD 148937, a binary system consisting of two massive stars surrounded by a bipolar nebula. Frost et al. monitored the binary system for 9 years, allowing them to determine its orbit and the properties of the constituent stars. They find that only one of the two stars is magnetic and that it appears to be younger than its companion. Using these data and theoretical models, the authors characterize the system’s evolution and conclude that the HD 148937 originally contained at least three stars; a stellar merger between two of the stars, which likely occurred only a few thousand years ago, produced the magnetic field in the merged star, and made it appear younger than its current binary companion. The same merger might also have produced the bipolar nebula surrounding the system. According to Frost et al., their inferred history of this system provides observational support for the proposal that stellar mergers produce magnetism in at least some massive stars.
A magnetic massive star has experienced a stellar merger
ARTICLE PUBLICATION DATE
12-Apr-2024
Beautiful nebula, violent history: Clash of stars solves stellar mystery
ESO
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THIS IMAGE, TAKEN WITH THE VLT Survey Telescope HOSTED AT ESO’S PARANAL OBSERVATORY, SHOWS THE BEAUTIFUL NEBULA NGC 6164/6165, ALSO KNOWN AS THE DRAGON’S EGG. THE NEBULA IS A CLOUD OF GAS AND DUST SURROUNDING A PAIR OF STARS CALLED HD 148937.
IN A NEW STUDY USING ESO DATA, ASTRONOMERS HAVE SHOWN THAT THE TWO STARS ARE UNUSUALLY DIFFERENT FROM EACH OTHER — ONE APPEARS MUCH YOUNGER AND, UNLIKE THE OTHER, IS MAGNETIC. MOREOVER, THE NEBULA IS SIGNIFICANTLY YOUNGER THAN EITHER STAR AT ITS HEART, AND IS MADE UP OF GASES NORMALLY FOUND DEEP WITHIN A STAR AND NOT ON THE OUTSIDE. THESE CLUES TOGETHER HELPED SOLVE THE MYSTERY OF THE HD 148937 SYSTEM — THERE WERE MOST LIKELY THREE STARS IN THE SYSTEM UNTIL TWO OF THEM CLASHED AND MERGED, CREATING A NEW, LARGER AND MAGNETIC STAR. THIS VIOLENT EVENT ALSO CREATED THE SPECTACULAR NEBULA THAT NOW SURROUNDS THE REMAINING STARS.
When astronomers looked at a stellar pair at the heart of a stunning cloud of gas and dust, they were in for a surprise. Star pairs are typically very similar, like twins, but in HD 148937, one star appears younger and, unlike the other, is magnetic. New data from the European Southern Observatory (ESO) suggest there were originally three stars in the system, until two of them clashed and merged. This violent event created the surrounding cloud and forever altered the system’s fate.
“When doing background reading, I was struck by how special this system seemed,” says Abigail Frost, an astronomer at ESO in Chile and lead author of the study published today in Science. The system, HD 148937, is located about 3800 light-years away from Earth in the direction of the Norma constellation. It is made up of two stars much more massive than the Sun and surrounded by a beautiful nebula, a cloud of gas and dust. “A nebula surrounding two massive stars is a rarity, and it really made us feel like something cool had to have happened in this system. When looking at the data, the coolness only increased.”
“After a detailed analysis, we could determine that the more massive star appears much younger than its companion, which doesn't make any sense since they should have formed at the same time!” Frost says. The age difference — one star appears to be at least 1.5 million years younger than the other — suggests something must have rejuvenated the more massive star.
Another piece of the puzzle is the nebula surrounding the stars, known as NGC 6164/6165. It is 7500 years old, hundreds of times younger than both stars. The nebula also shows very high amounts of nitrogen, carbon and oxygen. This is surprising as these elements are normally expected deep inside a star, not outside; it is as if some violent event had set them free.
To unravel the mystery, the team assembled nine years' worth of data from the PIONIER and GRAVITY instruments, both on ESO’s Very Large Telescope Interferometer (VLTI), located in Chile’s Atacama Desert. They also used archival data from the FEROS instrument at ESO’s La Silla Observatory.
“We think this system had at least three stars originally; two of them had to be close together at one point in the orbit whilst another star was much more distant,” explains Hugues Sana, a professor at KU Leuven in Belgium and the principal investigator of the observations. “The two inner stars merged in a violent manner, creating a magnetic star and throwing out some material, which created the nebula. The more distant star formed a new orbit with the newly merged, now-magnetic star, creating the binary we see today at the centre of the nebula.”
“The merger scenario was already in my head back in 2017 when I studied nebula observations obtained with the European Space Agency’s Herschel Space Telescope,” adds co-author Laurent Mahy, currently a senior researcher at the Royal Observatory of Belgium. “Finding an age discrepancy between the stars suggests that this scenario is the most plausible one and it was only possible to show it with the new ESO data.”
This scenario also explains why one of the stars in the system is magnetic and the other is not — another peculiar feature of HD 148937 spotted in the VLTI data.
At the same time, it helps solve a long-standing mystery in astronomy: how massive stars get their magnetic fields. While magnetic fields are a common feature of low-mass stars like our Sun, more massive stars cannot sustain magnetic fields in the same way. Yet some massive stars are indeed magnetic.
Astronomers had suspected for some time that massive stars could acquire magnetic fields when two stars merge. But this is the first time researchers find such direct evidence of this happening. In the case of HD 148937, the merger must have happened recently. “Magnetism in massive stars isn't expected to last very long compared to the lifetime of the star, so it seems we have observed this rare event very soon after it happened,” Frost adds.
ESO’s Extremely Large Telescope (ELT), currently under construction in the Chilean Atacama Desert, will enable researchers to work out what happened in the system in more detail, and perhaps reveal even more surprises.
More Information
This research was presented in a paper entitled “A magnetic massive star has experienced a stellar merger” to appear in Science (www.science.org/doi/10.1126/science.adg7700). The paper will be published by Science in print on Friday, 12 April 2024, and will be released online at 14:00 U.S. Eastern Time Thursday (20:00 CEST), 11 April 2024. For the final version of the embargoed paper, please check https://www.eurekalert.org/press/scipak/ or contact scipak@aaas.org while the embargo lasts.
It has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement number 772225: MULTIPLES; PI: Hugues Sana).
The European Southern Observatory (ESO) enables scientists worldwide to discover the secrets of the Universe for the benefit of all. We design, build and operate world-class observatories on the ground — which astronomers use to tackle exciting questions and spread the fascination of astronomy — and promote international collaboration for astronomy. Established as an intergovernmental organisation in 1962, today ESO is supported by 16 Member States (Austria, Belgium, Czechia, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom), along with the host state of Chile and with Australia as a Strategic Partner. ESO’s headquarters and its visitor centre and planetarium, the ESO Supernova, are located close to Munich in Germany, while the Chilean Atacama Desert, a marvellous place with unique conditions to observe the sky, hosts our telescopes. ESO operates three observing sites: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its Very Large Telescope Interferometer, as well as survey telescopes such as VISTA. Also at Paranal ESO will host and operate the Cherenkov Telescope Array South, the world’s largest and most sensitive gamma-ray observatory. Together with international partners, ESO operates ALMA on Chajnantor, a facility that observes the skies in the millimetre and submillimetre range. At Cerro Armazones, near Paranal, we are building “the world’s biggest eye on the sky” — ESO’s Extremely Large Telescope. From our offices in Santiago, Chile we support our operations in the country and engage with Chilean partners and society.
Warwick astronomer awarded £3 million to transform observations of the sky
A University of Warwick astronomer has been awarded £3 million to develop a ‘digital telescope’ that will be capable of producing a highly sensitive continuous movie of the night sky
CREDIT: CREDIT PROFESSOR DANNY STEEGHS, UNIVERSITY OF WARWICK.
A University of Warwick astronomer has been awarded £3 million to develop a ‘digital telescope’ that will be capable of producing a highly sensitive continuous movie of the night sky.
The new telescope will be used to detect explosive astrophysical events in real time, such as explosions of stars and merging of black holes. It will also be able to detect satellites, asteroids and hazardous space debris in orbit around the Earth.
A typical astronomical facility involves a telescope attached to a sophisticated mount, which moves to track the Earth’s rotation. This digital telescope, however, will include dozens of small stationary telescopes, each equipped with a state-of-the-art sensor. The stationary telescopes do not track the sky, so as the Earth rotates the stars drift through the fields of view of the telescopes.
Computers can then be used to correct for the Earth’s rotation and produce highly sensitive images of the sky. More sophisticated computer algorithms can be used to detect objects moving in any direction with any speed. This will typically include satellites and space debris, but potentially also include solar system objects approaching the Earth, such as asteroids and comets.
Professor Don Pollacco will lead the project which is funded by the European Research Council (ERC) in partnership with the University of Warwick (contributing an additional £600K).
The prototype digital telescope will include data from 52 telescopes and will most likely be located in the Canary Islands near the University of Warwick’s other facilities on the island of La Palma.
“Typical objects we are looking to detect include Supernova, which are explosions of stars at the end of their lives, and the merging of black holes and neutron stars, known as Gravitation Wave merger systems.
“The movie data can also be used to detect small pieces of space debris helping to alleviate the growing threat they pose to our satellites in near-Earth orbit. Knowing accurate orbits for debris and satellites allows us to record and remove them from the movie, hence giving a clearer astronomical view, as well as cataloguing the orbits of the debris itself.
“If the Digital Telescope works as we expect then its contribution will be transformational to both the study of astrophysical explosions and the population of artificial objects in near space. Furthermore, its data will have many uses in quite diverse astronomical research areas such as interstellar asteroids and long period exoplanets, amongst others.
“The main challenges of this project will be around the real-time data processing of enormous datasets, required for continuous observations of a large area of the sky.”
The funding, announced today (11th April), is part of the EU’s Horizon Europe programme. Professor Pollacco is announced as one of 255 outstanding research leaders in Europe set to be awarded ERC Advanced Grants.
Notes to Editors
About the ERC
The ERC, set up by the European Union in 2007, is the premier European funding organisation for excellent frontier research. It funds creative researchers of any nationality and age, to run projects based across Europe. The ERC offers four core grant schemes: Starting Grants, Consolidator Grants, Advanced Grants and Synergy Grants. With its additional Proof of Concept Grant scheme, the ERC helps grantees to bridge the gap between their pioneering research and early phases of its commercialisation. The ERC is led by an independent governing body, the Scientific Council. Since November 2021, Maria Leptin is the President of the ERC. The overall ERC budget from 2021 to 2027 is more than €16 billion, as part of the Horizon Europe programme, under the responsibility of European Commissioner for Innovation, Research, Culture, Education and Youth, Iliana Ivanova.
Physicists solve puzzle about ancient galaxy found by Webb telescope
UC Riverside study offers an explanation for dark matter distribution in a massive quiescent galaxy
UNIVERSITY OF CALIFORNIA - RIVERSIDE
IMAGE:
PHOTO SHOWS FROM L TO R: HAI-BO YU, DEMAO KONG, AND DANENG YANG.
RIVERSIDE, Calif. -- Last September, the James Webb Space Telescope, or JWST, discovered JWST-ER1g, a massive ancient galaxy that formed when the universe was just a quarter of its current age. Surprisingly, an Einstein ring is associated with this galaxy. That’s because JWST-ER1g acts as a lens and bends light from a distant source, which then appears as a ring — a phenomenon called strong gravitational lensing, predicted in Einstein’s theory of general relativity.
The total mass enclosed within the ring has two components: stellar and dark matter components.
“If we subtract the stellar mass from the total mass, we get the dark matter mass within the ring,” said Hai-Bo Yu, a professor of physics and astronomy at the University of California, Riverside, whose team has published new work about JWST-ER1g in the journal The Astrophysical Journal Letters. “But the value for the dark matter mass seems higher than expected. This is puzzling. In our paper, we offer an explanation.”
A dark matter halo is the halo of invisible matter that permeates and surrounds a galaxy like JWST-ER1g. Although dark matter has never been detected in laboratories, physicists are confident dark matter, which makes up 85% of the universe’s matter, exists.
“When ordinary matter — pristine gas and stars — collapses and condenses into the dark matter halo of JWST-ER1g, it may be compressing the halo, leading to a high density,” said Demao Kong, a second-year graduate student at UCR, who led the analysis. “Our numerical studies show that this mechanism can explain the high dark matter density of JWST-ER1g — more dark matter mass in the same volume, resulting in higher density.”
According to Daneng Yang, a postdoctoral researcher at UCR and co-author on the paper, JWST-ER1g, formed 3.4 billion years after the Big Bang, provides “a great chance to learn about dark matter.”
“This strong lensing object is unique because it has a perfect Einstein ring, from which we can obtain valuable information about the total mass within the ring, a critical step for testing dark matter properties,” he said.
Launched on Christmas Day in 2021, NASA’s JWST is an orbiting infrared observatory. Also called Webb, it is designed to answer questions about the universe. It is the largest, most complex, and powerful space telescope ever built.
“JWST provides an unprecedented opportunity for us to observe ancient galaxies formed when the universe was young,” Yu said. “We expect to see more surprises from JWST and learn more about dark matter soon.”
The study was supported by the John Templeton Foundation and the U.S. Department of Energy.
The title of the open access research paper is “Cold Dark Matter and Self-interacting Dark Matter Interpretations of the Strong Gravitational Lensing Object JWST-ER1.”
The University of California, Riverside is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment is more than 26,000 students. The campus opened a medical school in 2013 and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Center. The campus has an annual impact of more than $2.7 billion on the U.S. economy. To learn more, visit www.ucr.edu.
