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)
Friday, July 02, 2021
Floods may be nearly as important as droughts for future carbon accounting
STANFORD'S SCHOOL OF EARTH, ENERGY & ENVIRONMENTAL SCIENCES
Plants play an essential role in curbing climate change, absorbing about one-third of the carbon dioxide emitted from human activities and storing it in soil so it doesn't become a heat-trapping gas. Extreme weather affects this ecosystem service, but when it comes to understanding carbon uptake, floods are studied far less than droughts - and they may be just as important, according to new research.
In a global analysis of vegetation over more than three decades, Stanford University researchers found that photosynthesis - the process by which plants take up carbon dioxide from the atmosphere - was primarily influenced by floods and heavy rainfall nearly as often as droughts in many locations. The paper, published in Environmental Research Letters on June 29, highlights the importance of incorporating plant responses to heavy rainfall in modeling vegetation dynamics and soil carbon storage in a warming world.
"These wet extremes have basically been ignored in this field and we're showing that researchers need to rethink it when designing schemes for future carbon accounting," said senior study author Alexandra Konings, an assistant professor of Earth system science in Stanford's School of Earth, Energy & Environmental Sciences (Stanford Earth). "Specific regions might be much more important for flood impacts than previously thought."
More photosynthesis in combination with other factors can enable greater amounts of carbon to be stored in the soil over the long term, according to the researchers. To estimate the presence of photosynthesis, they analyzed plant greenness according to publicly available satellite data from 1981 to 2015.
Because the field of carbon accounting is dominated by research on drought impacts, the co-authors were surprised to find that photosynthesis was affected by flooding so frequently - in about half the regions in the analysis. While drought is known to decrease photosynthesis, wet extremes can either decrease or accelerate the process.
"I think the drought side is probably something that many of us understand clearly because we can see soils drying out - we know that plants need water to be able to function normally," said lead study author Caroline Famiglietti, a PhD student in Earth system science.
Using statistical analysis, the researchers divided the globe into regions and isolated periods during which the plants' photosynthetic activity wouldn't have resulted from other factors, such as temperature or sunlight changes. They then used several long-term soil moisture datasets to determine which locations were more sensitive to extreme wet events than to extreme dry events and found that many regions in central Mexico, eastern Africa and northern latitudes should be targeted for further investigation.
"Everything that is observed in this master dataset reflects the behavior of the broader climate system," Famiglietti said. "This paper identified something surprising, but it didn't answer all the questions we still have."
In a warmer world, extreme weather is projected to become more intense, extensive and persistent, but the mechanisms controlling drought responses in plants are much better understood than extreme wet responses. The findings suggest an opportunity to address "a big component of the uncertainty in future climate change and its links to ecosystem carbon storage," according to Konings.
"If we can better understand these processes, we can improve modeling and better prepare for the future," Famiglietti said.
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Konings is also a center fellow, by courtesy, of the Stanford Woods Institute for the Environment, and an assistant professor, by courtesy, of geophysics. Co-author Anna Michalak is affiliated with the Department of Earth System Science and the Carnegie Institution for Science.
The research was supported by the National Oceanic and Atmospheric Administration (NOAA).
Antibiotic-resistant bacteria found in cattle
Harmful bacteria are hiding in livestock; traditional methods aren't finding them
IMAGE: NEW RESEARCH FROM THE UNIVERSITY OF GEORGIA UNCOVERED ANTIMICROBIAL-RESISTANT SALMONELLA IN COWS. view more
CREDIT: ANDREW DAVIS TUCKER/UGA
Growing resistance to our go-to antibiotics is one of the biggest threats the world faces. As common bacteria like strep and salmonella become resistant to medications, what used to be easily treatable infections can now pose difficult medical challenges.
New research from the University of Georgia shows that there may be more antimicrobial-resistant salmonella in our food animals than scientists previously thought.
Using technology she developed, UGA researcher Nikki Shariat and Amy Siceloff, a first-year doctoral student in UGA's Department of Microbiology, found that traditional culturing methods used to test livestock for problematic bacteria often miss drug-resistant strains of salmonella. This finding has implications for treating sick food animals and the people who get infected by eating contaminated meat.
The study, published in Antimicrobial Agents and Chemotherapy, showed that 60% of cattle fecal samples contained multiple strains of salmonella that traditional testing methods missed. More alarmingly, Shariat found that about one out of every 10 samples tested positive for a drug-resistant strain of salmonella called Salmonella Reading. In addition to being antibiotic resistant, Salmonella Reading can cause severe illness in people.
A new technology emerges
Developed by Shariat in 2015, CRISPR-SeroSeq enables researchers to analyze all the types of salmonella present in a given sample. Traditional methods only examine one or two colonies of bacteria, potentially missing some strains of salmonella altogether. Shariat's technology identifies molecular signatures in salmonella's CRISPR regions, a specialized part of the bacteria's DNA. It also helps researchers identify which strains of the bacteria are most abundant.
In the current study, Shariat and colleagues found multiple salmonella strains in cattle feces before the animals were treated with the antibiotic tetracycline. After treatment, several of the dominant salmonella strains in the sample were wiped out, allowing Salmonella Reading to flourish.
Traditional culturing methods missed the antibiotic-resistant strain in the original samples. It was only once the antibiotic eliminated the more abundant strains that conventional methods were able to detect Salmonella Reading in the samples.
"This suggests that traditional tests have underestimated the amount of antibiotic-resistant bacteria in the past," said Shariat, an assistant professor of population health in the College of Veterinary Medicine.
But CRISPR-SeroSeq is a much more sensitive tool. It flagged the Salmonella Reading before antibiotic treatment.
"We need to know the antimicrobial resistance profiles of the bacteria that are present in animals," Shariat said. "That knowledge could make us change our choice of the type of antibiotic we use to treat ill animals. It can also help us select the best antibiotic for people who get sick from eating contaminated meat."
Missing the mark
Shariat's research shows that current surveillance efforts are likely underestimating the amount of antimicrobial resistance that exists.
Agencies that track antimicrobial resistance, like the FDA, USDA and CDC, among others, still rely on traditional sampling methods, which means they may be missing reservoirs of drug-resistant bacteria.
"The problem is you have hundreds of salmonella colonies in a given sample, but you only pick one or two of them to test," Shariat said. "It becomes a numbers game where researchers only pick the most abundant ones, and this means that they underestimate the different types of salmonella that are present."
Using CRISPR-SeroSeq can help fill that knowledge gap, giving researchers a better idea of how much antibiotic resistant bacteria exists. This information can help livestock farmers reduce and control outbreaks and guide policy on how to fight back against a growing public health threat.
CAPTION
Salmonella colonies growing on red indicator plates.
CREDIT
UGA
Co-authors of the paper include Amy Siceloff; Naomi Ohta, Keri Norman and Morgan Scott of Texas A&M University; Guy Loneragan of Texas Tech University; and Bo Norby of Michigan State University. This study was funded by the USDA National Institute of Food and Agriculture.
Cow masks? Agricultural company tries methane-absorbing wearable device
by Kristen Leigh Painter, Star Tribune Credit: CC0 Public Domain
Many humans adjusted to wearing masks last year for the greater good. Why not cows?
Cargill Inc. is partnering with Zelp Ltd., a U.K.-based startup, to distribute devices that are put over a dairy cow's nose to absorb methane released by their burps and exhales.
Minnetonka-based Cargill, with a sizable animal nutrition business in Europe, is working with dairy farmers there to gauge and shore up interest in using Zelp's cow-mask technology.
It's the latest in a series of experimental pilots, programs and technologies being explored by the mammoth agribusiness as it seeks to reduce the environmental toll of livestock within its supply chain.
"It's obviously reducing methane—that's the primary piece—but it also improves animal welfare because we are able to capture, analyze and process data about the animals and their behavior and eating habits," said Heather Tansey, sustainability director for Cargill's protein and animal nutrition businesses.
The wearable device is fitted on a harness and hangs over the cow's nostrils like a window awning. The accessory captures and converts methane, of which 90 to 95% is released through a cow's mouth through belches or exhalations, into carbon dioxide.
Zelp notes that while CO2 is also a greenhouse gas, methane is a far more potent contributor to warming the planet. Early trials suggest its devices effectively capture more than half the methane emissions created by the dairy cows.
As one of the world's largest purveyors of agricultural goods, Cargill is under constant pressure to clean up its supply chain in everything from palm oil to soy.
Its beef production, concentrated largely in North America, is arguably under the greatest consistent pressure because of the greenhouse gas emissions of ruminants.
Recent events have ratcheted up the scrutiny in new ways. The COVID-19 pandemic exposed vulnerabilities of a concentrated meat industry, with four major processors, including Cargill, controlling roughly 80% of the U.S. beef market.
The recent ransomware attack on competitor JBS U.S. again highlighted the influence the dominant meat companies have on the nation's supply of conventional proteins.
The Food and Agriculture Organization of the United Nations estimates that 14.5% of greenhouse gas emissions caused by human activity are due to the feeding, raising and processing of livestock. Last year Cargill rolled out its Beef Up program aimed at cutting its U.S. beef emissions by 30%.
Its efforts so far have largely been focused on partnering with conservation nonprofits and major U.S. retailers and restaurants, including McDonald's and Target, to expand soil health-improvement techniques, commonly called regenerative agriculture, that use specialized grazing practices to capture carbon in fields and pastures.
The cow-mask product is still in a trial period and, with Cargill's network of dairy farmers in Europe , could scale more quickly.
"If it is successful in capturing and converting methane to CO2, and you can scale it up and put it on a lot of farms ... then, yes, [meaningfully cutting emissions] is definitely a possibility," said Brad Heins, a dairy production professor and researcher at the University of Minnesota.
Cargill said it doesn't plan to bring the mask technology to the U.S. for use on beef cattle. But Heins said he believes such a device could easily be applied to a feedlot setting.
Perhaps the most important factor in the success of the apparatus will be the cost, Heins said.
"It has to beat a certain price point. There has to be some economic advantage to the farmer. Obviously economics drive a lot of their decisions," Heins said.
The company said it hasn't determined the cost of the device yet, and much of it depends on incentives given European dairy farmers, that according to a Cargill spokesman, are "rapidly evolving and will certainly have changed by the time we will go to market."
Zelp says the cows quickly adjust to the wearable device, which also collects data that can detect early signs of disease or when the cows are most fertile. The distributor partnership builds on Cargill's existing sales portfolio, which includes feed additives that claim to lower methane production within the animal's gut.
Tansey said the company sees a clear sales pitch for this device.
"We think there are some really interesting insights we are going to be able to gain with producers around sustainability," Tansey said. "There are a lot of downstream customers that are interested in reducing the impact of the milk they are buying."
Farmers looking to sell "climate-smart milk" that fetches a premium could see the financial benefit.
"We believe the farmers that will be interested in this product," Tansey said, "are ones selling to companies wanting a more sustainable supply chain."
THEY LIVE OFF BULLSHIT Fungi embrace fundamental economic theory as they engage in trading
Date: June 29, 2021
Source:Rice University
Summary: When you think about trade and market relationships, you might think about brokers yelling at each other on the floor of a stock exchange on Wall Street. But it seems one of the basic functions of a free market is quietly practiced by fungi.
New research from a Rice University economist suggests certain networks of fungi embrace an important economic theory as they engage in trading nutrients for carbon with their host plants. This finding could aid the understanding of carbon storage in soils, an important tool in mitigating climate change.
A research paper entitled "Walrasian equilibrium behavior in nature" is available online and will appear in an upcoming edition of Proceedings of the National Academy of Sciences. Ted Loch-Temzelides, a professor of economics and the George and Cynthia Mitchell Chair in Sustainable Development at Rice, examined through an economic lens data from ecological experiments on arbuscular mycorrhizal fungi networks, which connect to plants and facilitate the trading of nutrients for carbon.
Loch-Temzelides found that these relationships resemble how economists think about competitive -- also known as Walrasian -- markets. The paper demonstrates that Walrasian equilibrium, a leading concept in the economic theory of markets used to make predictions, can also be used to understand trade in this "biological market."
"Far from being self-sacrificing, organisms such as fungi can exhibit competitive behavior similar to that in markets involving sophisticated human participants," Loch-Temzelides said.
His finding also implies that resources are allocated to the maximum benefit of the market participants -- in this case, fungi and plants.
"Mycorrhizal fungi networks around the world are estimated to sequester around 5 billion tons of carbon per year," Loch-Temzelides said. "Manipulating the terms of trade so that carbon obtained from host plants becomes less expensive compared to nutrients could lead to additional carbon being stored in the soil, which could provide major benefits in fighting climate change."
Loch-Temzelides hopes future research by biologists and economists can make progress on better understanding these interactions.
Journal Reference: Ted Loch-Temzelides. Walrasian equilibrium behavior in nature. Proceedings of the National Academy of Sciences, 2021; 118 (27): e2020961118 DOI: 10.1073/pnas.2020961118
Cite This Page: MLA APA Chicago Rice University. "Fungi embrace fundamental economic theory as they engage in trading." ScienceDaily. ScienceDaily, 29 June 2021. <www.sciencedaily.com/releases/2021/06/210629161330.htm>.
Conservation aquaculture could bring more native oysters to west coast
Ten estuaries on the West Coast of North America have been identified as priority locations for expanding the use of conservation aquaculture in a study led by the Native Olympia Oyster Collaborative and funded by the Science for Nature and People Partnership (SNAPP). SNAPP is a research collaboration supported by the National Center for Ecological Analysis & Synthesis (NCEAS) at UC Santa Barbara.
The study, published in Plos One, recommends locations and methods for the strategic expansion of conservation aquaculture to bring back Olympia oyster populations -- both to local estuaries where they have most declined, and into more local restaurants for oyster lovers to dine on. The authors propose using aquaculture in these estuaries -- seven of which are in California -- in a win-win scenario that supports severely declined Olympia oyster populations, while also benefiting people, including local shellfish growers and Tribal communities.
"If you've eaten oysters on the half shell anywhere on the West Coast of North America, chances are good that you've been eating one of a few species introduced to the region for just that purpose," said April Ridlon, SNAPP postdoctoral scholar, collaborative lead of the Native Olympia Oyster Collaborative (NOOC) and lead author of the study. That's partly because the oyster native to this coast, the Olympia oyster (Ostrea lurida), was overfished in the Gold Rush era, and some populations -- faced with other stressors like habitat changes and sedimentation -- never recovered.
Humans have used aquaculture -- growing aquatic animals and plants to produce food -- for millennia." The oysters served at your local oyster bar have likely been grown first in a hatchery in tanks, then put out into a bay or estuary until they reach an appropriate size to be harvested and make it onto your plate," Ridlon said. "This same process can also be used to restore declining wild populations, similar to captive breeding programs for endangered species like California Condors and Hawaiian Monk Seals. Native oysters that are raised in a hatchery can be added to local estuaries permanently to help boost their numbers where populations have severely declined. Using aquaculture techniques to support wild populations of native species is what we call conservation aquaculture."
Restoration of Olympia oyster populations doesn't always require the use of aquaculture; many projects have been implemented across the species' range from British Columbia to Baja California, without using aquaculture at all (see the NOOC Restoration Site Map). Aquaculture techniques can also pose risks, including unintended negative ecological and genetic outcomes resulting from releasing hatchery-raised oysters into wild populations, many of which aren't well understood.
This new study thoroughly evaluates the risks and rewards, and recommends aquaculture only at ten priority estuaries where using it is critical to restore oyster populations, and where the benefits clearly outweigh the risks. Two priority estuaries are in the Puget Sound region of Washington: Northern Puget Sound and Whidbey Basin; one is in Oregon: Netarts Bay. The remaining seven are in California: Humboldt Bay, Tomales Bay, Richardson Bay, Elkhorn Slough, Morro Bay, Carpinteria Marsh, and Mugu Lagoon. Aquaculture can be used to support conservation efforts at all of these sites, without growing native oysters to harvest or sell them.
At some of the priority estuaries with good water quality and a nearby hatchery, commercial aquaculture and harvest also are possible, making this tool a unique way to support both oysters and people. In these estuaries, oyster offspring produced by commercial aquaculture may be swept into the bay and settle in local wild populations, increasing their numbers. Growers may also benefit from adding a new oyster species to those that they grow -- one that is more resilient to the diseases or climate-related events that can wipe out other oyster species entirely.
In Puget Sound, where the Olympia oyster once supported the shellfish industry, many farmers are already growing the native oyster, supported by a niche market of "foodies" looking for a different flavor and the "tide-to-table" experience. "Olys -- the industry nickname for Olympia oysters -- have a unique flavor profile. They're smaller than most other oysters and pack a punch of flavor," said Shina Wysocki, owner of Chelsea Farms Oyster Bar in Olympia, Wash. "They also provide an authentic connection to the traditional foodways of the West Coast." Puget Sound Restoration Fund (PSRF) has thoughtfully engaged with commercial growers to explore conservation aquaculture of Olympia oysters in the region, and hopes to continue this approach at the two priority estuaries identified by the study: Northern Puget Sound and Whidbey basin.
"This model of partnership between growers and restoration organizations could be used in other priority estuaries to expand the toolkit for bringing native oysters back to mudflats and menus in the future," said Betsy Peabody, executive director of PSRF.
And the Olympia oyster isn't the only marine species that can benefit from using aquaculture as a tool to restore its populations. "There is a growing interest in using conservation aquaculture for marine species globally -- to support native populations of everything from kelp to abalone to giant clams," said Tiffany Waters, co-author and global aquaculture manager for The Nature Conservancy. "This kind of collaborative research is so exciting, as it can be used as a model for other species and to provide win-win opportunities for both nature and people."
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A white dwarf living on the edge
Astronomers have identified a white dwarf so massive that it might collapse
IMAGE: THIS ILLUSTRATION HIGHLIGHTS A NEWFOUND SMALL WHITE DWARF, DISCOVERED BY ZTF, THAT IS 4,300 KILOMETERS ACROSS, OR ROUGHLY THE SIZE OF EARTH'S MOON, WHICH IS 3,500 KILOMETERS ACROSS. THE TWO... view more
CREDIT: GIUSEPPE PARISI
Maunakea and Haleakala, Hawai'i - Astronomers have discovered the smallest and most massive white dwarf ever seen. The smoldering cinder, which formed when two less massive white dwarfs merged, is heavy, "packing a mass greater than that of our Sun into a body about the size of our Moon," says Ilaria Caiazzo, the Sherman Fairchild Postdoctoral Scholar Research Associate in Theoretical Astrophysics at Caltech and lead author of the new study appearing in the July 1 issue of the journal Nature. "It may seem counterintuitive, but smaller white dwarfs happen to be more massive. This is due to the fact that white dwarfs lack the nuclear burning that keep up normal stars against their own self gravity, and their size is instead regulated by quantum mechanics."
The discovery was made by the Zwicky Transient Facility, or ZTF, which operates at Caltech's Palomar Observatory; two Hawai'i telescopes - W. M. Keck Observatory on Maunakea, Hawai'i Island and University of Hawai'i Institute for Astronomy's Pan-STARRS (Panoramic Survey Telescope and Rapid Response System) on Haleakala, Maui - helped characterize the dead star, along with the 200-inch Hale Telescope at Palomar, the European Gaia space observatory, and NASA's Neil Gehrels Swift Observatory.
White dwarfs are the collapsed remnants of stars that were once about eight times the mass of our Sun or lighter. Our Sun, for example, after it first puffs up into a red giant in about 5 billion years, will ultimately slough off its outer layers and shrink down into a compact white dwarf. About 97 percent of all stars become white dwarfs.
While our Sun is alone in space without a stellar partner, many stars orbit around each other in pairs. The stars grow old together, and if they are both less than eight solar-masses, they will both evolve into white dwarfs.
The new discovery provides an example of what can happen after this phase. The pair of white dwarfs, which spiral around each other, lose energy in the form of gravitational waves and ultimately merge. If the dead stars are massive enough, they explode in what is called a type Ia supernova. But if they are below a certain mass threshold, they combine together into a new white dwarf that is heavier than either progenitor star. This process of merging boosts the magnetic field of that star and speeds up its rotation compared to that of the progenitors.
Astronomers say that the newfound tiny white dwarf, named ZTF J1901+1458, took the latter route of evolution; its progenitors merged and produced a white dwarf 1.35 times the mass of our Sun. The white dwarf has an extreme magnetic field almost 1 billion times stronger than our Sun's and whips around on its axis at a frenzied pace of one revolution every seven minutes (the zippiest white dwarf known, called EPIC 228939929, rotates every 5.3 minutes).
"We caught this very interesting object that wasn't quite massive enough to explode," says Caiazzo. "We are truly probing how massive a white dwarf can be."
What's more, Caiazzo and her collaborators think that the merged white dwarf may be massive enough to evolve into a neutron-rich dead star, or neutron star, which typically forms when a star much more massive than our Sun explodes in a supernova.
"This is highly speculative, but it's possible that the white dwarf is massive enough to further collapse into a neutron star," says Caiazzo. "It is so massive and dense that, in its core, electrons are being captured by protons in nuclei to form neutrons. Because the pressure from electrons pushes against the force of gravity, keeping the star intact, the core collapses when a large enough number of electrons are removed."
If this neutron star formation hypothesis is correct, it may mean that a significant portion of other neutron stars take shape in this way. The newfound object's close proximity (about 130 light-years away) and its young age (about 100 million years old or less) indicate that similar objects may occur more commonly in our galaxy.
MAGNETIC AND FAST
The white dwarf was first spotted by Caiazzo's colleague Kevin Burdge, a postdoctoral scholar at Caltech, after searching through all-sky images captured by ZTF. This particular white dwarf, when analyzed in combination with data from Gaia, stood out for being very massive and having a rapid rotation.
"No one has systematically been able to explore short-timescale astronomical phenomena on this kind of scale until now. The results of these efforts are stunning," says Burdge, who, in 2019, led the team that discovered a pair of white dwarfs zipping around each other every seven minutes.
The team then analyzed the spectrum of the star using Keck Observatory's Low Resolution Imaging Spectrometer (LRIS), and that is when Caiazzo was struck by the signatures of a very powerful magnetic field and realized that she and her team had found something "very special," as she says. The strength of the magnetic field together with the seven-minute rotational speed of the object indicated that it was the result of two smaller white dwarfs coalescing into one.
Data from Swift, which observes ultraviolet light, helped nail down the size and mass of the white dwarf. With a diameter of 2,670 miles, ZTF J1901+1458 secures the title for the smallest known white dwarf, edging out previous record holders, RE J0317-853 and WD 1832+089, which each have diameters of about 3,100 miles.
In the future, Caiazzo hopes to use ZTF to find more white dwarfs like this one, and, in general, to study the population as a whole. "There are so many questions to address, such as what is the rate of white dwarf mergers in the galaxy, and is it enough to explain the number of type Ia supernovae? How is a magnetic field generated in these powerful events, and why is there such diversity in magnetic field strengths among white dwarfs? Finding a large population of white dwarfs born from mergers will help us answer all these questions and more."
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The study, titled "A highly magnetised and rapidly rotating white dwarf as small as the Moon," was funded by the Rose Hills Foundation, the Alfred P. Sloan Foundation, NASA, the Heising-Simons Foundation, the A. F. Morrison Fellowship of the Lick Observatory, the NSF, and the Natural Sciences and Engineering Research Council of Canada.
ABOUT LRIS
The Low Resolution Imaging Spectrometer (LRIS) is a very versatile and ultra-sensitive visible-wavelength imager and spectrograph built at the California Institute of Technology by a team led by Prof. Bev Oke and Prof. Judy Cohen and commissioned in 1993. Since then it has seen two major upgrades to further enhance its capabilities: the addition of a second, blue arm optimized for shorter wavelengths of light and the installation of detectors that are much more sensitive at the longest (red) wavelengths. Each arm is optimized for the wavelengths it covers. This large range of wavelength coverage, combined with the instrument's high sensitivity, allows the study of everything from comets (which have interesting features in the ultraviolet part of the spectrum), to the blue light from star formation, to the red light of very distant objects. LRIS also records the spectra of up to 50 objects simultaneously, especially useful for studies of clusters of galaxies in the most distant reaches, and earliest times, of the universe. LRIS was used in observing distant supernovae by astronomers who received the Nobel Prize in Physics in 2011 for research determining that the universe was speeding up in its expansion.
ABOUT W. M. KECK OBSERVATORY
The W. M. Keck Observatory telescopes are among the most scientifically productive on Earth. The two 10-meter optical/infrared telescopes atop Maunakea on the Island of Hawai?i feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrometers, and world-leading laser guide star adaptive optics systems. Some of the data presented herein were obtained at Keck Observatory, which is a private 501(c) 3 non-profit organization operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the Native Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.
The Goldilocks Supernova The discovery of a new type of supernova illuminates a medieval mysteryDate:June 28, 2021Source:University of California - Santa BarbaraSummary:Scientists have discovered the first convincing evidence for a new type of stellar explosion -- an electron-capture supernova. While they have been theorized for 40 years, real-world examples have been elusive. They are thought to arise from the explosions of massive super-asymptotic giant branch (SAGB) stars, for which there has also been scant evidence
A worldwide team led by UC Santa Barbara scientists at Las Cumbres Observatory has discovered the first convincing evidence for a new type of stellar explosion -- an electron-capture supernova. While they have been theorized for 40 years, real-world examples have been elusive. They are thought to arise from the explosions of massive super-asymptotic giant branch (SAGB) stars, for which there has also been scant evidence. The discovery, published in Nature Astronomy, also sheds new light on the thousand-year mystery of the supernova from A.D. 1054 that was visible all over the world in the daytime, before eventually becoming the Crab Nebula.
Historically, supernovae have fallen into two main types: thermonuclear and iron-core collapse. A thermonuclear supernova is the explosion of a white dwarf star after it gains matter in a binary star system. These white dwarfs are the dense cores of ash that remain after a low-mass star (one up to about 8 times the mass of the sun) reaches the end of its life. An iron core-collapse supernova occurs when a massive star -- one more than about 10 times the mass of the sun -- runs out of nuclear fuel and its iron core collapses, creating a black hole or neutron star. Between these two main types of supernovae are electron-capture supernovae. These stars stop fusion when their cores are made of oxygen, neon and magnesium; they aren't massive enough to create iron.
While gravity is always trying to crush a star, what keeps most stars from collapsing is either ongoing fusion or, in cores where fusion has stopped, the fact that you can't pack the atoms any tighter. In an electron capture supernova, some of the electrons in the oxygen-neon-magnesium core get smashed into their atomic nuclei in a process called electron capture. This removal of electrons causes the core of the star to buckle under its own weight and collapse, resulting in an electron-capture supernova.
If the star had been slightly heavier, the core elements could have fused to create heavier elements, prolonging its life. So it is a kind of reverse Goldilocks situation: The star isn't light enough to escape its core collapsing, nor is it heavy enough to prolong its life and die later via different means.
That's the theory that was formulated beginning in 1980 by Ken'ichi Nomoto of the University of Tokyo and others. Over the decades, theorists have formulated predictions of what to look for in an electron-capture supernova and their SAGB star progenitors. The stars should have a lot of mass, lose much of it before exploding, and this mass near the dying star should be of an unusual chemical composition. Then the electron-capture supernova should be weak, have little radioactive fallout, and have neutron-rich elements in the core.
The new study is led by Daichi Hiramatsu, a graduate student at UC Santa Barbara and Las Cumbres Observatory (LCO). Hiramatsu is a core member of the Global Supernova Project, a worldwide team of scientists using dozens of telescopes around and above the globe. The team found that the supernova SN 2018zd had many unusual characteristics, some of which were seen for the first time in a supernova.
It helped that the supernova was relatively nearby -- only 31 million light-years away -- in the galaxy NGC 2146. This allowed the team to examine archival images taken by the Hubble Space Telescope prior to the explosion and to detect the likely progenitor star before it exploded. The observations were consistent with another recently identified SAGB star in the Milky Way, but inconsistent with models of red supergiants, the progenitors of normal iron core-collapse supernovae.
The authors looked through all published data on supernovae, and found that while some had a few of the indicators predicted for electron-capture supernovae, only SN 2018zd had all six: an apparent SAGB progenitor, strong pre-supernova mass loss, an unusual stellar chemical composition, a weak explosion, little radioactivity and a neutron-rich core.
"We started by asking 'what's this weirdo?'" Hiramatsu said. "Then we examined every aspect of SN 2018zd and realized that all of them can be explained in the electron-capture scenario."
The new discoveries also illuminate some mysteries of the most famous supernova of the past. In A.D. 1054 a supernova happened in the Milky Way Galaxy that, according to Chinese and Japanese records, was so bright that it could be seen in the daytime for 23 days, and at night for nearly two years. The resulting remnant, the Crab Nebula, has been studied in great detail.
The Crab Nebula was previously the best candidate for an electron-capture supernova, but its status was uncertain partly because the explosion happened nearly a thousand years ago. The new result increases the confidence that the historic SN 1054 was an electron-capture supernova. It also explains why that supernova was relatively bright compared to the models: Its luminosity was probably artificially enhanced by the supernova ejecta colliding with material cast off by the progenitor star as was seen in SN 2018zd.
Ken Nomoto at the Kavli IPMU of the University of Tokyo expressed excitement that his theory had been confirmed. "I am very pleased that the electron-capture supernova was finally discovered, which my colleagues and I predicted to exist and have a connection to the Crab Nebula 40 years ago," he said. "I very much appreciate the great efforts involved in obtaining these observations. This is a wonderful case of the combination of observations and theory."
Hiramatsu added, "It was such a 'Eureka moment' for all of us that we can contribute to closing the 40-year-old theoretical loop, and for me personally because my career in astronomy started when I looked at the stunning pictures of the Universe in the high school library, one of which was the iconic Crab Nebula taken by the Hubble Space Telescope."
"The term Rosetta Stone is used too often as an analogy when we find a new astrophysical object," said Andrew Howell, a staff scientist at Las Cumbres Observatory and adjunct faculty at UCSB, "but in this case I think it is fitting. This supernova is literally helping us decode thousand-year-old records from cultures all over the world. And it is helping us associate one thing we don't fully understand, the Crab Nebula, with another thing we have incredible modern records of, this supernova. In the process it is teaching us about fundamental physics: how some neutron stars get made, how extreme stars live and die, and about how the elements we're made of get created and scattered around the universe." Howell also is the leader of the Global Supernova Project, and lead author Hiramatsu 's Ph.D. advisor.
Journal Reference: Daichi Hiramatsu, D. Andrew Howell, Schuyler D. Van Dyk, Jared A. Goldberg, Keiichi Maeda, Takashi J. Moriya, Nozomu Tominaga, Ken’ichi Nomoto, Griffin Hosseinzadeh, Iair Arcavi, Curtis McCully, Jamison Burke, K. Azalee Bostroem, Stefano Valenti, Yize Dong, Peter J. Brown, Jennifer E. Andrews, Christopher Bilinski, G. Grant Williams, Paul S. Smith, Nathan Smith, David J. Sand, Gagandeep S. Anand, Chengyuan Xu, Alexei V. Filippenko, Melina C. Bersten, Gastón Folatelli, Patrick L. Kelly, Toshihide Noguchi, Koichi Itagaki. The electron-capture origin of supernova 2018zd. Nature Astronomy, 2021; DOI: 10.1038/s41550-021-01384-2
Cite This Page: MLA APA Chicago University of California - Santa Barbara. "The Goldilocks Supernova: The discovery of a new type of supernova illuminates a medieval mystery." ScienceDaily. ScienceDaily, 28 June 2021. <www.sciencedaily.com/releases/2021/06/210628114136.htm>.
Physicists observationally confirm Hawking's black hole theorem for the first time
Physicists at MIT and elsewhere have used gravitational waves to observationally confirm Hawking’s black hole area theorem for the first time. This computer simulation shows the collision of two black holes that produced the gravitational wave signal, GW150914. Credit: Simulating eXtreme Spacetimes (SXS) project. Courtesy of LIGO
There are certain rules that even the most extreme objects in the universe must obey. A central law for black holes predicts that the area of their event horizons—the boundary beyond which nothing can ever escape—should never shrink. This law is Hawking's area theorem, named after physicist Stephen Hawking, who derived the theorem in 1971.
Fifty years later, physicists at MIT and elsewhere have now confirmed Hawking's area theorem for the first time, using observations of gravitational waves. Their results appear today in Physical Review Letters.
In the study, the researchers take a closer look at GW150914, the first gravitational wave signal detected by the Laser Interferometer Gravitational-wave Observatory (LIGO), in 2015. The signal was a product of two inspiraling black holes that generated a new black hole, along with a huge amount of energy that rippled across space-time as gravitational waves.
If Hawking's area theorem holds, then the horizon area of the new black hole should not be smaller than the total horizon area of its parent black holes. In the new study, the physicists reanalyzed the signal from GW150914 before and after the cosmic collision and found that indeed, the total event horizon area did not decrease after the merger—a result that they report with 95 percent confidence.
Their findings mark the first direct observational confirmation of Hawking's area theorem, which has been proven mathematically but never observed in nature until now. The team plans to test future gravitational-wave signals to see if they might further confirm Hawking's theorem or be a sign of new, law-bending physics.
"It is possible that there's a zoo of different compact objects, and while some of them are the black holes that follow Einstein and Hawking's laws, others may be slightly different beasts," says lead author Maximiliano Isi, a NASA Einstein Postdoctoral Fellow in MIT's Kavli Institute for Astrophysics and Space Research. "So, it's not like you do this test once and it's over. You do this once, and it's the beginning."
Isi's co-authors on the paper are Will Farr of Stony Brook University and the Flatiron Institute's Center for Computational Astrophysics, Matthew Giesler of Cornell University, Mark Scheel of Caltech, and Saul Teukolsky of Cornell University and Caltech.
An age of insights
In 1971, Stephen Hawking proposed the area theorem, which set off a series of fundamental insights about black hole mechanics. The theorem predicts that the total area of a black hole's event horizon—and all black holes in the universe, for that matter—should never decrease. The statement was a curious parallel of the second law of thermodynamics, which states that the entropy, or degree of disorder within an object, should also never decrease.
The similarity between the two theories suggested that black holes could behave as thermal, heat-emitting objects—a confounding proposition, as black holes by their very nature were thought to never let energy escape, or radiate. Hawking eventually squared the two ideas in 1974, showing that black holes could have entropy and emit radiation over very long timescales if their quantum effects were taken into account. This phenomenon was dubbed "Hawking radiation" and remains one of the most fundamental revelations about black holes.
"It all started with Hawking's realization that the total horizon area in black holes can never go down," Isi says. "The area law encapsulates a golden age in the '70s where all these insights were being produced."
Hawking and others have since shown that the area theorem works out mathematically, but there had been no way to check it against nature until LIGO's first detection of gravitational waves.
Hawking, on hearing of the result, quickly contacted LIGO co-founder Kip Thorne, the Feynman Professor of Theoretical Physics at Caltech. His question: Could the detection confirm the area theorem?
At the time, researchers did not have the ability to pick out the necessary information within the signal, before and after the merger, to determine whether the final horizon area did not decrease, as Hawking's theorem would assume. It wasn't until several years later, and the development of a technique by Isi and his colleagues, when testing the area law became feasible.
Before and after
In 2019, Isi and his colleagues developed a technique to extract the reverberations immediately following GW150914's peak—the moment when the two parent black holes collided to form a new black hole. The team used the technique to pick out specific frequencies, or tones of the otherwise noisy aftermath, that they could use to calculate the final black hole's mass and spin.
A black hole's mass and spin are directly related to the area of its event horizon, and Thorne, recalling Hawking's query, approached them with a follow-up: Could they use the same technique to compare the signal before and after the merger, and confirm the area theorem?
The researchers took on the challenge, and again split the GW150914 signal at its peak. They developed a model to analyze the signal before the peak, corresponding to the two inspiraling black holes, and to identify the mass and spin of both black holes before they merged. From these estimates, they calculated their total horizon areas—an estimate roughly equal to about 235,000 square kilometers, or roughly nine times the area of Massachusetts.
They then used their previous technique to extract the "ringdown," or reverberations of the newly formed black hole, from which they calculated its mass and spin, and ultimately its horizon area, which they found was equivalent to 367,000 square kilometers (approximately 13 times the Bay State's area).
"The data show with overwhelming confidence that the horizon area increased after the merger, and that the area law is satisfied with very high probability," Isi says. "It was a relief that our result does agree with the paradigm that we expect, and does confirm our understanding of these complicated black hole mergers."
The team plans to further test Hawking's area theorem, and other longstanding theories of black hole mechanics, using data from LIGO and Virgo, its counterpart in Italy.
"It's encouraging that we can think in new, creative ways about gravitational-wave data, and reach questions we thought we couldn't before," Isi says. "We can keep teasing out pieces of information that speak directly to the pillars of what we think we understand. One day, this data may reveal something we didn't expect."
The Acropolis, one of the most visited tourist sites in Greece, was shut during the afternoon due to soaring temperatures. Greece sizzled Thursday as temperatures topped 43 degrees Celsius (109 Fahrenheit), the year's hottest, with authorities warning the public to stay indoors if possible.
Temperatures have remained high for ten consecutive days, with the warmest weather expected in central Greece according to the national meteorological service.
Slightly higher temperatures had been recorded in July 2007 and 2000.
In Athens, authorities have made air conditioned halls available to the homeless, elderly and other vulnerable sections of the population.
The Acropolis, one of the most visited tourist sites in the country, was shut during the afternoon as a precaution.
Greece's civil protection has called for vigilance this week, in particular for the elderly and children who must hydrate regularly and avoid unnecessary sun exposure.
There is also a high risk of fire in several parts of the country, the agency said.
The fire department on Thursday said it was battling three notable blazes, the largest of them on the island of Crete. In July 1987, nearly 1,500 people died following one of the worst heat waves in Greek history.
Temperatures at the time had hovered around 43 degrees Celsius in Athens for several days in a row, at a time when few homes were equipped with air conditioning.
People keep riding a friendly dolphin in Texas. Experts warn it could be deadly mistake
by Mitchell Willetts
Credit: CC0 Public Domain
Texas wildlife experts are urging people to steer clear of a dolphin with a friendly reputation, out of concern for its safety.
The dolphin first started getting human attention over a year ago when it made the canals near a North Padre Island neighborhood just south of Corpus Christi its home, according to the National Oceanic and Atmospheric Administration's (NOAA) fisheries division.
"Over the past year the public has become more and more interested in the animal—even showing up to swim with, ride, jump on and pet the dolphin," NOAA said.
People have recorded their interactions with the dolphin, sharing them on social media and with friends, spurring even more residents and visitors to seek out the animal and interact with it.
"These actions could be dangerous—even fatal—for the dolphin," according to NOAA.
By interacting with the dolphin, it becomes comfortable around people, drawn to them, and even more likely to approach things it associates with humans, such as boats. This can lead to dolphins being hit by boats or getting stuck in fishing equipment.
Experts say the seemingly extroverted dolphin was recently spotted with a wound along its left side that appears to be from a boat propeller.
"It is clear that the dolphin is already in danger from the human interactions that are occurring," officials said.
NOAA is working with the Texas Marine Mammal Stranding Network (TMMSN) to keep tabs on the dolphin, monitoring its behavior and the severity of its injury.
While some have suggested relocating the dolphin, that won't work for several reasons, TMMSN said on social media.
First, the area is the dolphin's home, and moving it from a familiar place could leave the dolphin vulnerable, as it "may not be accepted by other dolphins," and may not know how to catch different kinds of prey in the new environment.
There's also the possibility that, if moved, it will continue doing what it has been in a different place—or worse, and teach other dolphins to interact with people, according to TMMSN.
Finally, the dolphin might just find its way back to where it was moved from.
"We view this as a human behavior problem," TMMSN said. "We know if people change their behavior, the dolphin's behavior will also change, and we can prevent future injuries to people and the dolphin."
NOAA says its Office of Law Enforcement will begin ticketing people seen petting, feeding, or riding the dolphin, with fines ranging from $100 to $250.
"Loving them from afar is the best way to insure a dolphin's ability to thrive and live a full life," the organization said.
To report violations, call the enforcement hotline at (800) 853-1964.
IMAGE: THE DOLICHOMITUS MEII WASP WAS DISCOVERED IN WESTERN AMAZONIA. ITS BODY LOOKS BLACK BUT GLITTERS ELECTRIC BLUE IN LIGHT. THE WASP LAYS ITS EGGS ON INSECT LARVAE LIVING DEEP IN... view more
CREDIT: FILIPPO DE GIOVANNI AND RODRIGO ARAÚJO
Researchers at the Biodiversity Unit of the University of Turku, Finland, study insect biodiversity particularly in Amazonia and Africa. In their studies, they have discovered hundreds of species previously unknown to science. Many of them are exciting in their size, appearance, or living habits.
"The species we have discovered show what magnificent surprises the Earth's rainforests can contain. The newly discovered Dolichomitus meii wasp is particularly interesting for its large size and unique colouring. With a quick glance, its body looks black but glitters electric blue in light. Moreover, its wings are golden yellow. Therefore, you could say it's like a flying jewel," says Postdoctoral Researcher Diego Pádua from the Instituto Nacional de Pesquisas da Amazônia (INPA) in Brazil, who has also worked at the Biodiversity Unit of the University of Turku.
Dolichomitus parasitoid wasps are parasitic on insect larvae living deep in tree trunks. They lay a single egg on the insect larva and the wasp hatchling eats the host larva as it develops.
"The ovipositor of the Dolichomitus meii wasp is immensely long. It sticks the ovipositor into holes in the wood and tries to find host larvae inside. The species' striking colouring protects it from birds that prey on insects. They do not snatch the wasp sitting on the tree trunk as they think it will taste bad or that it is dangerous," says Professor of Biodiversity Research Ilari E. Sääksjärvi from the University of Turku.
Polysphincta parasitoid wasps manipulate the behaviour of the host spider
At the same time as the publication on the Dolichomitus meii species, the researchers published another research article on South American wasp species. The article describes altogether seven new wasp species belonging to the Polysphincta genus.
The Polysphincta parasitoid wasps are parasitic on spiders. The female attacks a spider in its web and temporarily paralyses it with a venomous sting. After this, the wasp lays a single egg on the spider, and a larva hatches from the egg. The larva gradually consumes the spider and eventually pupates.
"The wasps that are parasitic on spiders are extremely interesting as many of them can manipulate the behaviour of the host spider. They can change the way a spider spins its web, so that before its death, the spider does not spin a normal web to catch prey. Instead, they spin a safe nest for the parasitoid wasp pupa," describes Professor Sääksjärvi.
Researchers at University of Turku have already discovered 53 new species this year
The new species are often discovered through extensive international collaboration. This was also the case with the newly published studies.
"For example, the discovery of the Dolichomitus meii species was an effort of six researchers. Moreover, these researchers all come from different countries," says Professor Sääksjärvi.
The work to map out biodiversity previously unknown to science continues at the University of Turku and there are interesting species discoveries ahead.
"I just counted that, in 2021, the researchers of the Biodiversity Unit at the University of Turku have described already 53 new species from different parts of the globe - and we're only halfway through the year," Sääksjärvi announces cheerfully.
The discoveries of the research group were published in the Biodiversity Data Journal and ZooKeys.
CAPTION
The name Polysphincta bonita refers to the species' beautiful appearance. The species is parasitic on spiders.
Credit: CC0 Public Domain
