The cosmic ‘Cow’ may have produced a new neutron star or black hole

A cosmic flare-up called the Cow seems to have left behind a black hole or neutron star.

When the flash was spotted in June 2018, astronomers debated its origins. Now, astrophysicist DJ Pasham of MIT and colleagues have seen the first direct evidence of what the Cow left behind. “We may be seeing the birth of a black hole or neutron star,” Pasham says.

The burst’s official, random designation is AT2018cow, but astronomers affectionately dubbed it the Cow. The light originated about 200 million light-years away and was 10 times as bright as an ordinary supernova, the explosion that marks the death of a massive star.

Astronomers thought the flare-up could have been from an unusual star being eaten by a black hole or from a weird sort of supernova that left behind a black hole or neutron star (SN: 6/21/19).

So Pasham and colleagues checked the Cow for flickering X-rays, which are typically produced close to a compact object, possibly in a disk of hot material around a black hole or on the surface of a neutron star.

Flickers in these X-rays can reveal the size of their source. The Cow’s X-rays flicker roughly every 4 milliseconds, meaning the object that produces them must be no more than 1,000 kilometers wide. Only a neutron star or a black hole fits the bill, Pasham and colleagues report December 13 in Nature Astronomy.

Because the Cow’s flash was from the explosion that produced either of these objects, a preexisting black hole was probably not responsible for the burst. Pasham admits he was hoping for a black hole eating an exotic star. “I was a little bit disappointed,” he says. “But I’m more blown away that this could be direct evidence of the birth of a black hole. This is an even cooler result.”

Cold plasma could transform the sustainable farms of the future

Physicist Stephan Reuter of Polytechnique Montréal spends most days using his expertise in energy and matter to improve medical technologies. Recently though, he stood in a sea of green to consider how a shower of charged particles might affect lettuce.

He had been invited to one of the largest commercial greenhouses in Quebec to help the growers rethink the energy of agriculture. Inside the building, encased by glass walls and covering more ground than four soccer fields, thousands upon thousands of lettuce plants floated on polystyrene mats in a hydroponic, or no-soil, growing system. The crop was nearly ready to be picked, packaged and shipped. Reuter’s task was to use physics to help the company, Hydroserre Inc. in Mirabel, reduce its carbon footprint.

To that end, the company is interested in finding new ways to fight pathogens and to deliver fertilizer to the growing plants. Many fertilizers contain ammonia, which is produced from nitrogen (necessary for plant growth) and hydrogen using a chemical reaction called the Haber-Bosch process. This process revolutionized agriculture in the early 20th century by making mass production of fertilizer possible. However, the process yields hundreds of millions of metric tons of carbon dioxide each year.

“Ideally, we want a fertilizer that’s renewable,” Reuter says. And to make it truly green, it should be created at the farm, making transport, another carbon emitter, unnecessary. Reuter and a growing number of chemists, physicists and engineers think they can see how to make that happen. These researchers are working toward future farms that are truly sustainable, where the energy from renewable sources like wind or solar is harnessed to make an efficient fertilizer on-site. They hope to realize this vision by exploiting plasma.
Reuter might seem an unlikely consultant for an agricultural challenge. After all, his expertise is in the physics of plasma, one of the four fundamental states of matter, along with solids, liquids and gases.

Plasma is remarkably common. In fact, most matter seen in the known universe — more than 99.9 percent, according to astrophysicists — is in a plasma state. Lightning produces plasma. So do those inexpensive novelty lamps in museum gift shops. Switch on the power, and an electrode at the sphere’s center produces a high voltage that interacts with the gas sealed inside the glass to form tendrils of colored plasma that radiate outward. Touch the glass, and the plasma tendrils seem to reach toward your fingers.

The sun is a ball of plasma and gas. The solar wind is a stream of plasma that peels off the sun (SN: 12/21/19 & 1/4/20, p. 6). When that wind collides with the protective, plasma-rich magnetic cushion that envelopes Earth, the interactions produce rivers of light seen in the aurora borealis and aurora australis.

Plasma is also a workhorse of modern technology. Engineers use it to etch the millions of tiny transistors found on the chips in today’s computers, cars and musical birthday cards. The pixels in plasma televisions contain gas that forms a plasma, sealed inside tiny cells sandwiched between two glass plates, and neon signs and fluorescent lights glow because of plasma. Some former astronauts even predict that plasma engines will someday propel us to Mars.

But what exactly is plasma? It’s a soup of electrons with their negative charges, positive ions and neutral atoms that also produces electromagnetic fields and ultraviolet and infrared radiation. Plasma comes about when gas gets super energized — by heat or an electric current, for example — and electrons are freed from atoms.

Plasmas occur naturally or can be human-made. When produced by high temperatures, such as in the sun, it’s called “hot plasma,” while the plasma created in a plasma ball and other room-temperature, low-pressure environments is called “cold plasma.” Plasma balls make it easy to see: They’re filled with a gaseous mixture that includes one of the very stable, noble gases, like argon, xenon, neon or krypton. Plasma makes up those glowing tendrils that reach out from the center. The high-frequency current excites electrons that then separate from the atoms of gas. Many agricultural experiments include a mix of noble gases and air to yield ions of nitrogen and oxygen.
Scientists have long been interested in plasma’s biological implications. In the late 19th century, the Finnish physicist Karl Selim Lemström observed that the width of growth rings in fir trees near the Arctic Circle followed the cycle of the aurora borealis, widening when the northern lights were strongest. He hypothesized that the light show somehow encouraged plant growth. To artificially emulate the northern lights, he placed a metal wire net over growing plants and ran a current through it. Under the right conditions, he reported, the treatment produced larger vegetable yields.

For decades, scientists have known that exposure to plasma can safely kill pathogenic bacteria, fungi and viruses. Small studies in animals also suggest that plasma can prompt the growth of blood vessels in skin. In his research, Reuter studies ways to harness these properties to inhibit new infections in wounds and expedite healing or treat other skin conditions. But more recently, he and other physicists have been working on ways to use the power of plasma to improve food production.

Experiments conducted in the last decade or so have tested a mix of ways to apply plasma to seeds, seedlings, crops and fields. These include plasma generated using noble gases, as well as plasma generated from air. In some cases, plasma is directly applied through plasma “jets” that stream over the seeds or plants. Another approach uses plasma-treated water that can do double duty: irrigation and fertilization. Some studies have reported a range of benefits, from helping plants grow faster and bigger to resisting pests.

“Even in this very, very early stage of research that we’re at with plasma, which has really only come into its own in the last 10 to 15 years, we’re seeing very promising data,” says plant pathologist Brendan Niemira at the Food Safety and Intervention Technologies Research unit at the U.S. Department of Agriculture’s Eastern Regional Research Center in Wyndmoor, Pa. He’s a fan of the approach: On Zoom, Niemira’s avatar shows an almond basking in an eerie, purple plasma glow.

The challenge now, he says, is to figure out whether plasma can deliver at the level of hectares of crops. “Can we make it work in a field environment [to] deliver an advantage that can be integrated into grow systems in the future?”

Nested within that challenge are many others, including finding a way to deliver plasma to plants on a large scale, confirming benefits reported in lab studies and showing that plasma is better than current methods. And, finally, figuring out what the charged soup of plasma is actually doing to plants.

Recent advances became possible, Niemira says, largely because in the 1990s and early 2000s, scientists developed efficient and cost-effective ways to generate cold plasmas by streaming high-energy electrons into a gas. Those electrons would collide with gas molecules, knocking off electrons and producing charged particles. Since then, he says, there’s been something of a rush to test plasma on plants at all stages of growth and with a range of strategies.
Surface changes
One of the most appealing uses of plasma, according to Reuter, is as a fertilizer alternative to ammonia. His plan for the Mirabel greenhouse project, which he helped launch in spring 2021 with scientists from the Quebec-based nonprofit IRDA, or Research and Development Institute for the Agri-Environment, goes something like this: The plasma is generated by sending an electric current through a gas that, ideally, is just air. That process creates a mix of charged and neutral particles, including electrons and ions, that can produce reactive species of nitrogen and oxygen. In tabletop experiments and then in the greenhouse, Reuter and his colleagues will enrich water with plasma, then study whether it can reduce pathogens and affect the growing plants.

Reactive species, as the name implies, are ready to react with atoms and molecules, including in living things, and are biologically available to plants. When the plasma is added to the water, those reactive species dissolve. The resulting plasma-infused water, with its biologically available nitrogen, will then be used to irrigate the plants. It will do the same job as ammonia: Nitrogen, which plants require for growth, is delivered as ions, excited molecules and compounds in the water. While heavy doses of reactive species can harm plant cells or DNA, the amount in plasma-treated water has been shown to be safe for the plant, Reuter says.
Experiments led by biochemist Alexander Volkov of Oakwood University in Huntsville, Ala., offer another example of the kind of research going on in plasma agriculture. Volkov studies the ways in which plants and electromagnetism interact. For example, he’s shown how an electric stimulus can trigger the closing mechanism on a Venus flytrap.

Recently, Volkov set out to study how plasma would affect 20 seeds of dragon’s-tongue, a cultivar of the bush bean Phaseolus vulgaris. The experiment was low-tech. He and colleagues balanced the seeds on a plasma ball for one minute each, then incubated the seeds in water for seven hours. Two days later, the scientists found that in plasma-treated seeds, the radicle — the little protrusion of root that makes a seed a seedling — measured 2.7 centimeters, compared with 1.8 centimeters in untreated seeds, a gain of 50 percent. The team reported the results in Functional Plant Biology in February 2021.
Less than a centimeter of extra growth may seem modest, but Volkov was encouraged. The benefit couldn’t have come from the reactive species of nitrogen and oxygen because they can’t exit the glass sphere, but somehow, the treated seeds seemed to take up more water to grow faster.

To investigate that idea, he and colleagues studied the seeds using an atomic force microscope and magnetic resonance imaging, which reveals how tissues take up water. At the micrometer-level view of the atomic force microscope, Volkov saw that exposure had roughed up the surface of the seeds. The images looked like carved mountain ranges. Those ridges gave the water more surface area to glom on to, and more openings through which to soak the inside of the seeds, he hypothesized. MRI images of treated beans showed larger swaths of white — indicating more water inside — than untreated beans.

“When we use the plasma balls or lamps, the water can penetrate easily through the pores and accelerate germination,” he says.
Growing evidence
Physicist Nevena Puač of the Institute of Physics Belgrade in Serbia has performed dozens of studies testing plasma on plants and has been working in the field for decades. She says most studies — successful or not — have tested two ideas: plasma as a disinfectant or as a growth instigator.

On the disinfecting front, plasma jet treatments of less than a minute on foods including apples, cherry tomatoes and lettuce can reduce disease-causing bacteria, such as Escherichia coli, Salmonella and Listeria. Some studies have looked at higher exposure times as well: In a 2008 study, five minutes of plasma treatment inactivated 90 percent of pathogenic Aspergillus parasiticus fungi on hazelnuts, peanuts and pistachios.

This is the research branch that Niemira works on as well. In May 2019 in LWT–Food Science and Technology, he and colleagues showed that plasma treatment combined with an existing sanitizer killed 99.9 percent of Listeria on apples in under four minutes. Working alone, the sanitizer achieved comparable results after an hour. The combination works much better than either one could possibly work alone, he says.

Investigations on seed germination and plant growth are similarly promising. Researchers at the Chinese Academy of Sciences in Nanjing exposed soybean seeds to plasma. Seven days after exposure, the roots were up to 27 percent heavier than roots from untreated seeds, the team reported in 2014. The same year, researchers in Romania reported similar gains for radish roots and sprouts.

At last year’s Gaseous Electronics Conference, hosted online by the American Physical Society, researchers from Japan presented results from a study of young seedlings treated directly with plasma and with plasma-treated water in a rice paddy in the Aichi prefecture. Plants treated directly with plasma early in the growth process had up to a 15 percent higher yield than untreated plants. But treating plants late in the growth process lowered the yield. Timing matters, Puač says. So does the application method: In some cases in the experiments in Japan, plasma-treated water actually lowered the yield.

“To my knowledge this was the first study where plants were treated directly,” rather than as seeds or after harvest for disinfection, says engineer Katharina Stapelmann of North Carolina State University in Raleigh, who organized the session.

Studies have connected plasma treatment to a range of benefits, Puač says, from growth rate to yield. But other studies suggest that plasma won’t ever be a one-size-fits-all technology.

Researchers in South Korea reported in the Journal of Physics D: Applied Physics in 2020, for example, that while a six-minute plasma exposure boosted germination rates of barley sprouts, an 18-minute exposure, over three days, produced no benefit in growth and lowered total plant weight. Experimental results published in 2000 looked at the effects of direct plasma jets on peas, corn and radishes and found detrimental effects that varied by the gas used in the plasma. The seeds were exposed for two to 20 minutes, and seeds with prolonged exposure were slower to germinate than untreated seeds.
What the research shows, Reuter says, is that before plasma becomes a staple on farms around the world, scientists need to better understand the myriad ways that the fourth state of matter could affect plants.

For instance, successful outcomes for plants might be due in part to the UV radiation produced by plasma; UV radiation has long been used as a disinfectant. The reactive nitrogen and oxygen species, which can be helpful or harmful to living cells depending on how they’re used, probably help as nutrients and disinfectants, as well. Plasma also produces electric and magnetic fields and infrared and visible light. Their impact on plants also hasn’t been fully explored. Even though researchers know what’s in the plasma, and can see how the plants respond, they don’t have the details mapped out, Volkov says.

Gardens big and small
Projects are under way around the world to test plasma on large scales and in different settings. Dutch scientists working in Uganda have developed portable “reactors” that use plasma to generate fertilizers from the air. They hope this invention can meet the need for fertilizers in places where farmers often can’t get ammonia. Early in 2022, Reuter hopes to report his first results from desktop experiments. The hydroponic growing system at Hydroserre will provide him with the opportunity to refine his method.

With any luck, he says, the project will show a way for future farms to replace ammonia and reduce carbon emissions.

While researchers and growers await those results, citizen scientists, amateur physicists and experimental gardeners have been known to make space in the shed for a plasma ball next to their rakes and shovels, to run their own experiments at home.

Volkov has jumped in. When the pandemic shut down his lab last year, he took his work — and his plasma balls — home. He bathed the vegetable seeds for his garden for a minute in the lamp’s rich, purplish glow, and then planted them.

“It was cucumber, tomatoes, eggplants, cabbage,” he says. A backyard test run isn’t proof of anything, Volkov readily acknowledges, and any gardener can attest that a finicky combination of variables can make or break a garden.

But he did see an astounding harvest last fall. By late October, he was still picking big, ripe tomatoes from the vines grown from plasma-treated seeds, at a time when the plants from untreated seeds have often withered. The cucumbers were bigger and juicier. The cabbages, planted in a friend’s nursery, were heavier and more delicious, he says. “I got a fantastic amount of everything.”

50 years ago, scientists were on the trail of ‘memory molecules’

The first memory molecule has been isolated, characterized and synthesized … [from the brains of] rats that had been shocked in the dark…. It is a protein and dubbed “scotophobin,” after the Greek words for “fear of the dark.” [One researcher] has injected synthetic rat scotophobin into the brains of hundreds of goldfish. While the fish indeed exhibited fear of the dark and resisted learning to swim into the dark, the fear was of brief duration.

The idea that scotophobin stores memories and can be used to transfer them between organisms was met with intense skepticism and was eventually discredited by neuroscientists. But the search for a physical basis of memory continues. Over the last few decades, other memory molecule candidates have popped up, including a protein called PKM-zeta, which may help with memory retrieval, and even RNA (SN: 6/9/18, p. 9). Still, the dominant theory is that memories are stored in synapses, connections between nerve cells in the brain (SN: 2/3/18, p. 22).

Seeking solutions to climate change

Jeremy Freeman
Scientist and designer

When he was featured in 2016, Jeremy Freeman was developing new tools and methods to help scientists better analyze brain data. Now he is executive director of CarbonPlan, a nonprofit organization that he founded in March 2020 to tackle the climate crisis through open-source data and research.

You’ve shifted gears since 2016. Tell us about it.
I moved very far from neuroscience, and I’m now exclusively working on climate change. Our focus [at CarbonPlan] is the scientific integrity and transparency of climate solutions. [We do] a combination of research on different areas of climate science and strategies for addressing climate change. We [also] produce a variety of resources and tools for both the research community and the public at large.

Despite being a radically different field, there are some interesting commonalities, in terms of the value of having very accessible, open, publicly available data that speaks to critical issues. [For climate change,] issues around both what is changing in the climate and how we might address that, in different strategies we might take. Having as much of that information be developed in the open, in a way that others can contribute to, and making work available for others to read and evaluate and criticize and engage with — those are [also] values I felt really strongly about in the world of biomedical science.

What CarbonPlan work are you most proud of right now?
We have done a lot of analysis identifying very specific ways in which the implementation of forest carbon offset programs [the planting or preservation of trees to attempt to compensate for carbon emissions] haven’t worked. We did a comprehensive analysis of the role of forest carbon offsets in California’s cap-and-trade program, which is a massive sort of market of offsets on the order of $2 billion, and we identified about $400 million worth of offset credits that in our analysis do not reflect real climate benefits because of errors in how they were calculated with respect to issues that involve fundamental problems in statistics and ecology.

That team effort, led by Grayson Badgley and Danny Cullenward, along with a lot of other work that we’ve done on the role of offsets, is really starting to change the conversation, and wake people up to the fact that these approaches to dealing with climate change haven’t been working.

What other questions are you looking at?
There’s an area known as carbon removal, which refers to any mechanisms that draw down CO2 from the atmosphere. And carbon removal is really, really complicated, because there are a lot of different ways to potentially accomplish that.… So that’s an area where we’ve been very involved, studying, analyzing, comparing. We helped write, edit and produce a book called the CDR Primer — carbon dioxide removal primer. It’s, of course, a publicly available resource.

Have recent social justice movements influenced your work?
Absolutely.… Climate change is so fundamentally an issue of equity and an issue of justice. The burdens of climate change are going to be borne by those who were not directly responsible for it, and those who in many ways have been responsible for it will be more able to avoid its impacts. And there’s a deep injustice in that.… How to think about that is an important aspect of our work.… We’re interested in finding a way to be really complementary to a lot of existing community efforts around these issues.

— Interview by Aina Abell

Pluto’s dark side reveals clues to its atmosphere and frost cycles

Pluto’s dark side has come into dim view, thanks to the light of the dwarf planet’s moon.

When NASA’s New Horizons spacecraft flew past Pluto in 2015, almost all the images of the dwarf planet’s unexpectedly complex surface were of the side illuminated by the sun (SN: 7/15/15). Darkness shrouded the dwarf planet’s other hemisphere. Some of it, like the area near the south pole, hadn’t seen the sun for decades.

Now, mission scientists have finally released a grainy view of the dwarf planet’s dark side. The researchers describe the process to take the photo and what it tells them about how Pluto’s nitrogen cycle affects its atmosphere October 20 in the Planetary Science Journal.

Before New Horizons passed by Pluto, the team suspected the dwarf planet’s largest moon, Charon, might reflect enough light to illuminate the distant world’s surface. So the researchers had the spacecraft turn back toward the sun to take a parting peek at Pluto.
At first, the images just showed a ring of sunlight filtering through Pluto’s hazy atmosphere (SN: 7/24/15). “It’s very hard to see anything in that glare,” says planetary scientist John Spencer of the Southwest Research Institute in Boulder, Colo. “It’s like trying to read a street sign when you’re driving toward the setting sun and you have a dirty windshield.”

Spencer and colleagues took a few steps to make it possible to pull details of Pluto’s dark side out of the glare. First, the team had the spacecraft take 360 short snapshots of the backlit dwarf planet. Each was about 0.4 seconds long, to avoid overexposing the images. The team also took snapshots of the sun without Pluto in the frame so that the sun could be subtracted out after the fact.

Tod Lauer of the National Optical Astronomy Observatory in Tucson, Ariz., tried to process the images when he got the data in 2016. At the time, the rest of the data from New Horizons was still fresh and took up most of his attention, so he didn’t have the time to tackle such a tricky project.

But “it was something that just sat there and ate away at me,” Lauer says. He tried again in 2019. Because the spacecraft was moving as it took the images, each image was a little bit smeared or blurred. Lauer wrote a computer code to remove that blur from each individual frame. Then he added the reflected Charon light in each of those hundreds of images together to produce a single image.
“When Tod did that painstaking analysis, we finally saw something emerging in the dark there … giving us a little bit of a glimpse of what the dark pole of Pluto looks like,” Spencer says.

That the team got anything at all is impressive, says planetary scientist Carly Howett, also of the Southwest Research Institute and who is on the New Horizons team but was not involved in this work. “This dataset is really, really hard to work with,” she says. “Kudos to this team. I wouldn’t have wanted to do this.”

The image, Howett says, can help scientists understand how Pluto’s frigid nitrogen atmosphere varies with its decades-long seasons. Pluto’s atmosphere is controlled by how much nitrogen is in a gas phase in the air and how much is frozen on the surface. The more nitrogen ice that evaporates, the thicker the atmosphere becomes. If too much nitrogen freezes to the ground, the atmosphere could collapse altogether.
When New Horizons was there, Pluto’s south pole looked darker than the north pole. That suggests there was not a lot of fresh nitrogen frost freezing out of the atmosphere there, even though it was nearing winter. “The previous summer ended decades ago, but Pluto cools off pretty slowly,” Spencer says. “Maybe it’s still so warm [that] the frost can’t condense there, and that keeps the atmosphere from collapsing.”

There was a bright spot in the middle of the image, which could be a fresh ice deposit. That’s also not surprising, Howett says. The ices may still be moving from the north pole to the south pole as Pluto moves deeper into its wintertime.

“We’ve thought this for a long time. It makes sense,” she says. “But it’s nice to see it happening.”

50 years ago, corporate greenwashing was well under way

Environmental advertising: A question of integrity— Science News, November 27, 1971

A new report published by the Council on Economic Priorities clearly outlines facts showing that much corporate advertising on environmental themes is irrelevant or even deceptive.… A large percentage of the environmental advertising comes from companies that are the worst polluters.

Concerns about “greenwashing,” a term coined in the 1980s to describe the practice of organizations marketing their products as environmentally friendly when they are not, have persisted into the current climate crisis. As more consumers have become environmentally conscious, corporations’ greenwashing tactics have evolved. For instance, some energy companies in the United States have claimed that natural gas is a “clean” energy source because the power plants emit less carbon dioxide than coal plants. But natural gas plants can emit large amounts of methane, a potent greenhouse gas. In 2022, the U.S. Federal Trade Commission plans to review its “Green Guides,” rules for companies that make environmental claims.