Thanks to timely measurements from specialized orbiting telescopes, Rice University astrophysicist Matthew Baring and colleagues were able to test a new theory about a possible cause for the rare slowdown, or “anti-glitch,” of SGR 1935+2154, a highly magnetic type of neutron star known as a magnetar.

In a study published this month in Nature Astronomy, Baring and co-authors used X-ray data from the European Space Agency’s X-ray Multi-Mirror Mission (XMM-Newton) and NASA’s Neutron Star Interior Composition Explorer (NICER) to analyze the magnetar’s rotation. They showed the sudden slowdown could have been caused by a volcano-like rupture on the surface of the star that spewed a “wind” of massive particles into space. The research identified how such a wind could alter the star’s magnetic fields, seeding conditions that would be likely to switch on the radio emissions that were subsequently measured by China’s Five-hundred-meter Aperture Spherical Telescope (FAST).

“People have speculated that neutron stars could have the equivalent of volcanoes on their surface,” said Baring, a professor of physics and astronomy. “Our findings suggest that could be the case and that on this occasion, the rupture was most likely at or near the star’s magnetic pole.”

SGR 1935+2154 and other magnetars are a type of neutron star, the compact remains of a dead star that collapsed under intense gravity. About a dozen miles wide and as dense as the nucleus of an atom, magnetars rotate once every few seconds and feature the most intense magnetic fields in the universe.

Magnetars emit intense radiation, including X-rays and occasional radio waves and gamma rays. Astronomers can decipher much about the unusual stars from those emissions. By counting pulses of X-rays, for example, physicists can calculate a magnetar’s rotational period, or the amount of time it takes to make one complete rotation, as the Earth does in one day. The rotational periods of magnetars typically change slowly, taking tens of thousands of years to slow by a single rotation per second.

Glitches are abrupt increases in rotational speed that are most often caused by sudden shifts deep within the star, Baring said.

“In most glitches, the pulsation period gets shorter, meaning the star spins a bit faster than it had been,” he said. “The textbook explanation is that over time, the outer, magnetized layers of the star slow down, but the inner, non-magnetized core does not. This leads to a buildup of stress at the boundary between these two regions, and a glitch signals a sudden transfer of rotational energy from the faster spinning core to the slower spinning crust.”

Abrupt rotational slowdowns of magnetars are very rare. Astronomers have only recorded three of the “anti-glitches,” including the October 2020 event.

While glitches can be routinely explained by changes inside the star, anti-glitches likely cannot. Baring’s theory is based on the assumption that they are caused by changes on the surface of the star and in the space around it. In the new paper, he and his co-authors constructed a volcano-driven wind model to explain the measured results from the October 2020 anti-glitch.

Baring said the model uses only standard physics, specifically changes in angular momentum and conservation of energy, to account for the rotational slowdown.

“A strong, massive particle wind emanating from the star for a few hours could establish the conditions for the drop in rotational period,” he said. “Our calculations showed such a wind would also have the power to change the geometry of the magnetic field outside the neutron star.”

The rupture could be a volcano-like formation, because “the general properties of the X-ray pulsation likely require the wind to be launched from a localized region on the surface,” he said.

“What makes the October 2020 event unique is that there was a fast radio burst from the magnetar just a few days after the anti-glitch, as well as a switch-on of pulsed, ephemeral radio emission shortly thereafter,” he said. “We’ve seen only a handful of transient pulsed radio magnetars, and this is the first time we’ve seen a radio switch-on of a magnetar almost contemporaneous with an anti-glitch.”

Baring argued this timing coincidence suggests the anti-glitch and radio emissions were caused by the same event, and he’s hopeful that additional studies of the volcanism model will provide more answers.

“The wind interpretation provides a path to understanding why the radio emission switches on,” he said. “It provides new insight we have not had before.”

The research was supported by the National Science Foundation (1813649), NASA (80NSSC22K0397), Japan’s RIKEN Advanced Science Institute and Taiwan’s Ministry of Science and Technology.

Ethylene is a commodity chemical used to manufacture a wide range of products from plastics to antifreeze. The large-scale production of ethylene is energy intensive and relies heavily on fossil resources. Electrocatalytic production of ethylene from CO₂ is emerging as a promising method. This new catalyst consists of only earth-abundant materials, such as nickel and copper, and requires less energy for chemical reaction.

Long Qi, a scientist at Ames Lab, explained how the catalyst works. Atomically dispersed nickel anchored on nitrogen assembly carbon (NAC) works to catalyze CO₂ to CO at low voltage and high current. The catalyst is effective over a wide range of voltages and its effectiveness at higher currents means a higher rate of CO production.

“Since this catalyst remains active over a very wide voltage range, that allows easy coupling with a second catalyst,” Qi said. “So we use the second catalyst, which is a copper nanowire, and by combining these two we have a very selective process that has up to 60% efficiency going from CO₂ to ethylene in one pot.”

Another important aspect of the catalyst is its structure. Wenyu Huang, an Ames Lab scientist and Iowa State University professor from the team, noted that the catalyst’s porous structure enhances its effectiveness. “Our catalyst has an ordered mesoporous structure that is beneficiary for mass transfer,” he said. “Because it’s highly porous, you have a very high surface area to expose a lot of nickel’s active sites, making our catalyst very effective in CO₂ reduction to CO.”

For Huang, the most exciting aspect of this research was how the team combined the two catalysts to streamline the process. “We basically combine the two best catalysts on their own, and they work together so we can connect the CO₂ to CO and the CO to ethylene reactions in one system,” he said.

Qi emphasized the importance of using CO₂ as a feedstock for this reaction, because it addresses the global need to reduce the amount of CO₂ released into the atmosphere. He explained that this process can use CO₂ recovered from chemical or industrial processes, or from air capture. “And we can do this without any precious metal, simply the nickel, copper, carbon, and nitrogen, to permit large-scale industrial applications,” Qi said. “Also, we potentially eliminate the use of fossil resources to make ethylene.”

Lead investigator MaryAnne Drake, PhD, of the North Carolina State University Department of Food, Bioprocessing and Nutrition Sciences, Raleigh, NC, USA, explained that “milk is more susceptible to packaging-related off-flavors than many other beverages because of its mild, delicate taste.” Besides light oxidation, “milk’s taste can be impacted by the exchange of the packaging’s compounds into the milk and by the packaging absorbing food flavors and aromas from the surrounding refrigeration environment.”

To quantify the flavor impacts of packaging, the researchers examined pasteurized whole and skim milk stored in six half pint containers: paperboard cartons, three plastic jugs (made from different plastics), a plastic bag, and glass as a control. The milk was stored in total darkness to control for light oxidation and kept cold at 4°C (39°F).

The samples were tested on the day of first processing, then again at 5, 10, and 15 days after. A trained panel examined the sensory properties of each sample, and the research team conducted a volatile compound analysis to understand how the packaging was intermingling with the milk. Finally, the samples underwent a blind consumer taste test on day 10 to see whether tasters could tell any difference between milk stored in the paperboard carton or the plastic jug compared with milk packaged in glass.

The results showed that package type doesinfluence milk flavor, and skim milk is more susceptible to flavor impacts than whole milk. Of the different packaging types, paperboard cartons and the plastic bag preserved milk freshness the least due to the paperboard’s absorption of milk flavor and the transfer of paperboard flavor into the milk. Milk packaged in paperboard cartons, in fact, showed distinct off-flavors as well as the presence of compounds from the paperboard. The final results show that, while glass remains an ideal container for preserving milk flavor, plastic containers provide additional benefits while also maintaining freshness in the absence of light exposure.

Paperboard cartons are the most widely used packaging type for school meal programs in the United States, so these findings are especially relevant for the consideration of how young children consume and enjoy milk.

“These findings suggest that industry and policymakers might want to consider seeking new package alternatives for milk served during school meals,” said Drake. Over time, the consequences of using milk packaging that contributes significant off-flavors may affect how young children perceive milk in both childhood and adulthood.

Methane is the second most important greenhouse gas after carbon dioxide, contributing about 1 degree Fahrenheit of present-day global warming relative to pre-industrial times. One major source of methane to the atmosphere is the extraction and transport of oil and gas. Countries are obligated to report their greenhouse gas emissions to international bodies such as the United Nations Framework Convention on Climate Change, but recent studies suggest that the current methods for calculating methane emissions rely on outdated and incomplete information and may not accurately represent actual emissions.

A recent study from researchers at Princeton University and Colorado State University finds that the current method for estimating methane emissions from offshore oil and gas production in the United Kingdom systematically and severely underestimates emissions. The study finds that as much as five times more methane is being emitted from oil and gas production in the UK than what the government has reported. The researchers reached this conclusion by critically evaluating the UK’s current method of calculating methane emissions, suggesting alternative, peer-review based methods and generating revised emission estimates.

Sincemany other countries use similar methodologies to calculate methane emissions from oil and gas production, this severe underestimation is likely not confined to the UK alone.

“It is critical to know when, where and how much methane is emitted from each of its sources in order to prioritize emission reductions,” said Denise Mauzerall, a co-author and core faculty member of the Center for Policy Research on Energy and the Environment at Princeton University. “We hope our work will facilitate improved emission estimates and reductions not only from the UK but also from other countries producing methane from oil and gas extraction,” Mauzerall said.

Due to its climate and indirect health impacts (methane is a precursor for ozone which is an air pollutant that damages human health and crops), methane mitigation has recently become a global policy priority. Its relatively short lifetime of about 12 years and high heat trapping ability per molecule makes reducing methane emissions among the most effective ways to slow the rate of climate warming. As a result, in 2021 countries signed the Global Methane Pledge, committing to reduce methane emissions by at least 30% of 2020 levels by 2030. To track progress, countries compile national emissions data into inventories, such as the UK’s National Atmospheric Emissions Inventory (NAEI), which are then reported to international monitoring bodies.

This study focuses on methane leakage associated with discovery, extraction, and production of oil and natural gas. These methane emissions are typically calculated by multiplying the activity level of various processes – namely venting, flaring, processing and combustion activities on production platforms, offshore oil loading, and gas transfer by high-pressure pipelines – by “emission factors,” which are standard estimates of the methane emissions associated with each activity.

The researchers found that the emissions factors used in the UK’s reporting are either outdated, rely on unpublished or publicly unavailable industry research, or use generic values recommended by the IPCC. Furthermore, these emission factors are usually “static,” meaning that they are not sensitive to factors such as environmental conditions and management practices which could affect emissions from various processes. In addition, leakage can occur when the off-shore rigs are idle – an “activity” that does not currently have an associated emission factor.

Noting these shortcomings, the researchers updated and revised estimation techniques for each process, and, wherever possible, used dynamic rather than static emission factor formulations that account for varying environmental conditions. They also incorporated direct boat-based measurements of methane concentrations around offshore gas platforms in the North Sea collected in summer 2017, documented in a study also led by the authors. These updates resulted in a total methane emission estimate more than five times larger than reported emissions.

“Methane emissions from offshore facilities are currently largely uncertain, and because sources on facilities only emit for a short time period, using direct survey methods such as satellite or drones will probably only capture about 25% of the actual emissions,” said Stuart Riddick, lead author and research scientist at Colorado State University. “To generate representative baseline emissions across the sector, we need to work with industry to develop practical, effective, and collaborative measurement strategies,” Riddick said.

Previous research has shown that reducing leakage across the oil and natural gas supply chain can advance climate and air quality goals while also being economically profitable – a win-win opportunity for industry and climate.

This study adds to a growing base of literature finding that current measurements of anthropogenic methane emission inventories are too low. With the world’s first “global stocktake” on progress implementing the Paris Agreement concluding in 2023, the researchers argue that improved measurement of emissions deserves urgent attention.

“We are hopeful that our work will facilitate more accurate emission inventory development and lead to critically important reductions of methane leakage – a win for both industry and the environment,” Mauzerall said.