MUTUAL AID

Fishing in synchrony brings mutual benefits for dolphins and people in Brazil, research shows

Peer-Reviewed Publication

OREGON STATE UNIVERSITY

 

IMAGE: TRADITIONAL COOPERATIVE FISHING BETWEEN LAHILLE'S BOTTLENOSE DOLPHINS AND ARTISANAL NET-CASTING FISHERS IN LAGUNA, BRAZIL. view more 

CREDIT: PHOTO BY MAURICIO CANTOR, DEPARTMENT OF FISHERIES, WILDLIFE AND CONSERVATION SCIENCES, MARINE MAMMAL INSTITUTE, OREGON STATE UNIVERSITY.

NEWPORT, Ore. – By working together, dolphins and net-casting fishers in Brazil each catch more fish, a rare example of an interaction by two top predators that is beneficial to both parties, researchers have concluded following 15 years of study of the practice.

“We knew that the fishers were observing the dolphins’ behavior to determine when to cast their nets, but we didn’t know if the dolphins were actively coordinating their behavior with the fishers,” said Mauricio Cantor of Oregon State University’s Marine Mammal Institute, who led the study.

“Using drones and underwater imaging, we could observe the behaviors of fishers and dolphins with unprecedented detail and found that they catch more fish by working in synchrony,” said Cantor, an assistant professor in OSU’s College of Agricultural Sciences. “This shows that this is a mutually beneficial interaction between the humans and the dolphins.”

The researchers’ findings were just published in the Proceedings of the National Academy of Sciences. Co-authors of the paper are Professor Fábio Daura-Jorge of the Universidade Federal de Santa Catarina in Brazil and Professor Damien Farine of the University of Zurich and the Australian National University.

Synchronized movements of flocks of birds and schools of fish are a common yet striking behavior that can be key to the animals’ survival. Synchronized behavior between species, like that between the Lahille’s bottlenose dolphins and the traditional net-casting fishers in Brazil, is much more rare.

The practice is considered a cultural tradition in the city of Laguna on Brazil’s southern coast, where it occurred for more than 140 years and has been passed down through generations of fishers and dolphins. The cooperative fishing relationship is specific to this population of dolphins and is not a genetic trait in the animals, Cantor said.

There are historical and recent accounts of similar behaviors in a handful of locations elsewhere in the world, but the practice is in decline or has disappeared completely in most places and remains almost completely unstudied in others. The rare nature of the practice is one reason the practice in Brazil is being considered for a cultural heritage designation, he said.

“From the fishers’ perspective, this practice is part of the culture of the community in all kinds of ways,” Cantor said. “They acquire skills passed down from other fishers and knowledge is spread through social learning. They also feel connected to this place and have a sense of belonging to the community.”

Predictive models run as part of the study show that the future of the practice could be threatened if populations of mullet – the type of fish both dolphins and people are seeking – continue to decline, or future generations of fishers lose interest in learning the art of this unique fishing practice.

“The practice is unlikely to continue if either the dolphins or the fishers no longer benefit from it,” said Farine.

Daura-Jorge said researchers are already seeing early signs of decline in the practice. “If we take steps to document and conserve the knowledge and the culture of the practice, we can indirectly and positively impact the biological aspects, as well,” he said.

To better understand this cultural tradition and measure its short- and long-term consequences for both fishers and dolphins, the researchers combined drones, hydrophones and underwater cameras to capture the mechanics of the partnership, conducted long-term demographic surveys for dolphins and interviewed and observed the fishers.

They found that foraging synchrony between dolphins and fishers substantially increases the probability of catching fish and the number of fish caught. This benefit then supports the dolphins’ survival – dolphins who engage in cooperative fishing in this area have a 13% increase in survival rates – and the socioeconomic wellbeing of the fishers. They also found that the fishers’ understanding of the fishing tradition matched the evidence produced through scientific tools and methods.

“Questionnaires and direct observations are different ways to look at the same phenomenon, and they match up well,” Cantor said. “By integrating these together, we could then get the most complete and reliable picture of how this system works and, most importantly, how it benefits both fishers and dolphins.”

Most interspecific interactions, including those between humans and other animals, are competitive rather than mutually beneficial, the researchers said.

“But not in this case,” Farine said. “This makes this system of substantial scientific interest, as it can help us to understand under what conditions cooperation can evolve and – of growing importance in our rapidly changing world – under what conditions it might go extinct, or flip from a cooperative to a competitive interaction.”

The researchers suggest conservation action is needed to ensure the future of the practice. Both the dolphins and the fishers are reliant on a strong and healthy fish population for the cooperative relationship to succeed. In recent years, the region has seen reduced availability of fish. There is also reduced interest in learning the tradition, said Daura-Jorge, who has been monitoring this population for the past 15 years. 

“We don’t know what is going to happen in the future, but our best guess, using our best data and best models, is that if things keep going the way they are right now, there will be a time when the interaction will no longer be of interest by at least one of the predators – the dolphins or the fishers,” Daura-Jorge said.  

The researchers suggest several conservation measures may be necessary to secure the future of the practice. First is to try to identify the source of the mullet decline and take measures to better manage that species, such as reducing use of illegal nets through law enforcement, Daura-Jorge said.

Second, the researchers recommend steps to work with current and future artisanal fishers, stressing the cultural and economic importance of the net-casting practice. That might include offering incentives to encourage the traditional practice, such as setting a premium price for fish caught with this method.

“This phenomenon of mutually-beneficial interaction between wildlife and humans is getting more and more rare and seems to be at global risk,” Cantor said. “The cultural value and the biological diversity are important, and it’s important to preserve it.”

A dolphin giving a cue to a fisher at Praia da Tesoura in Laguna, Brazil.

An artisanal net-caster fishes in Laguna, Brazil.

CREDIT

Photo by Fabio G. Daura-Jorge, Departamento de Ecologia e Zoologia, Universidade Federal de Santa Catarina, Florianópolis SC, Brazil

JOURNAL

Proceedings of the National Academy of Sciences

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Foraging synchrony drives resilience in human-dolphin mutualism

Warmer climate may drive fungi to be more dangerous to our health

Pathogen’s mutations ramp up as heat rises, causing concern for new infectivity

Peer-Reviewed Publication

DUKE UNIVERSITY

 

IMAGE: THIS PHOTOMICROGRAPH DEPICTS CRYPTOCOCCUS NEOFORMANS A FUNGAL PATHOGEN THAT HAS BEEN CAUSING AN INCREASING NUMBER OF LIFE-THREATENING INFECTIONS. PEOPLE WITH AIDS, AND THOSE USING IMMUNOSUPPRESSIVE DRUGS ARE MOST VULNERABLE. view more 

CREDIT: U.S. CENTERS FOR DISEASE CONTROL

DURHAM, N.C. – The world is filled with tiny creatures that find us delicious. Bacteria and viruses are the obvious bad guys, drivers of deadly global pandemics and annoying infections. But the pathogens we haven’t had to reckon with as much – yet – are the fungi.

Pathogenic fungi (Candida, Aspergillus, Cryptococcus and others) are notorious killers of immune-compromised people. But for the most part, healthy people have not had to worry about them, and the vast majority of the planet’s potentially pathogenic fungi don’t do well in the heat of our bodies.

But all that may be about to change.

A new study out of Duke University School of Medicine finds that raised temperatures cause a pathogenic fungus known as Cryptococcus deneoformans to turn its adaptative responses into overdrive. This increases its number of genetic changes, some of which might presumably lead to higher heat resistance, and others perhaps toward greater disease-causing potential.

Specifically, higher heat makes more of the fungus’ transposable elements, or jumping genes, get up and move around within the fungal DNA, leading to changes in the way its genes are used and regulated. The findings appeared Jan. 20 in the Proceedings of the National Academy of Sciences.

“These mobile elements are likely to contribute to adaptation in the environment and during an infection,” said postdoctoral researcher Asiya Gusa Ph.D. of Molecular Genetics and Microbiology in the Duke School of Medicine. “This could happen even faster because heat stress speeds up the number of mutations occurring.”

This may ring a bell with viewers of the new HBO series “The Last of Us,” where a dystopian hellscape is precipitated by a heat-adapted fungus that takes over humans and turns them into zombies. “That’s exactly the sort of thing I’m talking about -- minus the zombie part!” said Gusa who just watched the first episode and who will join the Duke faculty as an assistant professor later this year.

“These are not infectious diseases in the communicable sense; we don’t transmit fungi to each other,” Gusa said. “But the spores are in the air. We breathe in spores of fungi all the time and our immune systems are equipped to fight them.”

Fungal spores are generally larger than viruses, so your existing stock of face masks against Covid would probably be sufficient to stop them. That, and your body heat, for now.

”Fungal diseases are on the rise, largely because of an increase in the number of people who have weakened immune systems or underlying health conditions,” Gusa said. But at the same time, pathogenic fungi may be adapting to warmer temperatures as well.

Working in the lab of Professor Sue Jinks-Robertson, Gusa led research that focused on three transposable elements that were particularly active under heat stress in C. deneoformans. But there are easily another 25 or more transposable elements in that species that could mobilize, she said.

The team used ‘long-read’ DNA sequencing to see changes that might otherwise have been missed, Gusa said. Computational analysis allowed them to map transposons and then see how they had moved. “We have improved tools now to see these movements that were previously hiding in our blind spots.”

Heat stress sped the mutations up. Following 800 generations of growth in laboratory medium, the rate of transposon mutations was five-times higher in fungi raised at body temperature (37 Celsius) compared with fungi raised at 30C.

One of the transposable elements, called T1, had a tendency to insert itself between coding genes, which could lead to changes in the way genes are controlled. An element called Tcn12 often landed within the sequence of a gene, potentially disrupting that gene’s function and possibly leading to drug resistance. And a third kind, Cnl1, tended to land near or in the telomere sequences at the ends of chromosomes, an effect which Gusa said isn’t fully understood.

The mobilization of transposable elements also appeared to increase more in fungi living in mice than in lab culture. “We saw evidence of all three transposable elements mobilizing in the fungus genome within just ten days of infecting the mouse,” Gusa said. The researchers suspect that the added challenges of surviving in an animal with immune responses and other stressors may drive the transposons to be even more active.

“This is a fascinating study, which shows how increasing global temperature may affect the fungal evolution in unpredictable directions,” said Arturo Casadevall MD, PhD, the chair of molecular microbiology & immunology at Johns Hopkins University. “As the world warms, transposons in soil fungi like Cryptococcus neoformans could become more mobile and increase genomic changes in ways that could enhance virulence and drug resistance. One more thing to worry about with global warming!”

Gusa’s work was helped by collaboration with Duke labs that also study fungi, the Joseph Heitman lab in the school of medicine and the Paul Magwene lab in Trinity Arts & Sciences.

The next phase of this research will be looking at pathogens from human patients who have had a relapsing fungal infection. “We know that these infections can persist and then come back with potential genetic changes.”

It’s time to get serious about pathogenic fungi, Gusa said. “These kinds of stress-stimulated changes may contribute to the evolution of pathogenic traits in fungi both in the environment and during infection. They may be evolving faster than we expected.”

This research was supported by the National Institutes of Health (R35-GM118077, R21-AI133644, 5T32AI052080, 2T32AI052080, 1K99-AI166094-01, R01-AI039115-24, R01-AI050113-17, R01-AI133654-05)

CITATION: “Genome-Wide Analysis of Heat Stress-Stimulated Transposon Mobility in the Human Fungal Pathogen Cryptococcus deneoformans,” Asiya Gusa, Vikas Yadav, Cullen Roth, Jonathan Williams, Evan Meil Shouse, Paul Magwene, Joseph Heitman, Sue Jinks-Robertson. Proceedings of the National Academy of Sciences, Jan. 20, 2023. DOI: 10.1073/pnas.2209831120

Online - https://www.pnas.org/doi/10.1073/pnas.2209831120

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JOURNAL

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2209831120 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Genome-Wide Analysis of Heat Stress-Stimulated Transposon Mobility in the Human Fungal Pathogen Cryptococcus deneoformans

"

The Colour out of Space" by H. P. Lovecraft

https://www.hplovecraft.com › writings › texts › fiction

Aug 20, 2009 — It was just a colour out of space—a frightful messenger from unformed realms of infinity beyond all Nature as we know it; from realms whose mere .

Global survey of attacks by large carnivores reveals distinct patterns in low- and high-income countries

Attacks reported in high-income countries mostly occur during recreation and less likely to be fatal

Peer-Reviewed Publication

PLOS

 

IMAGE: MOST PREDATORY ATTACKS OCCURRED IN LOW-INCOME REGIONS, ESPECIALLY INDIA (72%) AND SOUTH-EASTERN AFRICA (14%), WHERE LEOPARDS WERE AMONG THE MOST FREQUENTLY INVOLVED FELIDS. FOR MOST ENCOUNTERS, THE VICTIMS OF LEOPARDS WERE MAINLY CHILDREN. view more 

CREDIT: VINCENZO PENTERIANI (CC-BY 4.0, HTTPS://CREATIVECOMMONS.ORG/LICENSES/BY/4.0/)

Reports of large carnivore attacks on humans have increased since 1970, but the frequency and context of these attacks depends on socioeconomic and environmental factors, according to a new study of over 5,000 reports publishing January 31st in the open access journal PLOS Biology by Giulia Bombieri of MUSE Science Museum in Italy, Vincenzo Penteriani of the National Museum of Natural Science (CSIC) in Spain, and colleagues.

The researchers collected information about reported attacks on humans by 12 species of carnivores in three families (Ursidae, Felidae, and Canidae) between 1970 and 2019 from published and unpublished scientific papers, web pages, and news reports. They identified 5,089 reported attacks by large carnivores that resulted in injury, of which 32% were fatal. The number of reported attacks increased over the 49-year period, particularly in lower-income countries.

Attacks in high-income countries were most common during recreational activities, such as hiking, camping, or dog-walking, whereas nearly 90% of attacks in low-income countries occurred during livelihood-related activities like farming, fishing, or grazing livestock. Wild felids and canids were responsible for more predatory attacks, but bears were more likely to attack when surprised, defending cubs, or in food-related interactions such as scavenging human food. Most fatal attacks occurred in lower-income countries where tigers and lions are present.

The authors say that approaches to reduce large carnivore attacks should be tailored to the socioeconomic context. In high-income countries, campaigns to educate visitors and residents in large carnivore areas about high-risk behaviors and how to avoid dangerous encounters could be effective. In contrast, in lower-income countries, where co-existence with large carnivores is mostly involuntary, zoning changes that separate humans and livestock from large carnivore habitats, expanding protected areas, and restoring habitat connectivity, would be more appropriate strategies. These preventative measures may be challenging to implement as the global population grows.

Penteriani adds, “When human recreational and/or livelihood activities overlap with large carnivore ranges, it is crucial to understand how to live with species that can pose threats to humans. Factors triggering large carnivore attacks on humans depend on the combination of local socio-economic and ecological factors, which implies that measures to reduce large carnivore attacks must consider the diverse local ecological and social contexts.”

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In your coverage, please use this URL to provide access to the freely available paper in PLOS Biology: http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3001946

Citation: Bombieri G, Penteriani V, Almasieh K, Ambarlı H, Ashrafzadeh MR, Das CS, et al. (2023) A worldwide perspective on large carnivore attacks on humans. PLoS Biol 21(1): e3001946. https://doi.org/10.1371/journal.pbio.3001946

Author Countries: Italy, Spain, Iran, Turkey, Germany, India, United States of America, Mexico, Tanzania, Venezuela, Russia, Nepal, Kenya, Malaysia, JapanFunding: VP was financially supported by the Project PID2020-114181GB-I00 financed by the Spanish Ministry of Science and Innovation, the Agencia Estatal de Investigación (AEI), and the Fondo Europeo de Desarrollo Regional (FEDER, EU). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Large felids such as lions caused more deaths in general, with 65% of felid attacks being fatal, followed by canids (49%) and ursids (9%). Most fatal attacks occurred in lower-income countries and lion attacks were mainly predatory, i.e., incidents where humans were attacked with the likely purpose of being consumed.

Ursids were mainly involved in involuntary sudden encounters (45%), defensive reactions by females with cubs (18%) or food-related interactions (16%), such as bears defending a carcass, or being surprised while attacking livestock or feeding on anthropogenic food.

CREDIT

Vincenzo Penteriani (CC-BY 4.0, https://creativecommons.org/licenses/by/4.0/)

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JOURNAL

PLoS Biology

DOI

10.1371/journal.pbio.3001946 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

 

First Kilonova Progenitor System identified

Astronomers using the SMARTS 1.5-meter Telescope uncover a one-in-ten-billion binary star system

Peer-Reviewed Publication

ASSOCIATION OF UNIVERSITIES FOR RESEARCH IN ASTRONOMY (AURA)

 

IMAGE: THIS IS AN ARTIST’S IMPRESSION OF THE FIRST CONFIRMED DETECTION OF A STAR SYSTEM THAT WILL ONE DAY FORM A KILONOVA — THE ULTRA-POWERFUL, GOLD-PRODUCING EXPLOSION CREATED BY MERGING NEUTRON STARS. THESE SYSTEMS ARE SO PHENOMENALLY RARE THAT ONLY ABOUT 10 SUCH SYSTEMS ARE THOUGHT TO EXIST IN THE ENTIRE MILKY WAY. view more 

CREDIT: CTIO/NOIRLAB/NSF/AURA/J. DA SILVA/SPACEENGINE/M. ZAMANI

Astronomers using the SMARTS 1.5-meter Telescope at Cerro Tololo Inter-American Observatory in Chile, a Program of NSF's NOIRLab, have uncovered the first example of a phenomenally rare type of binary star system, one that has all the right conditions to eventually trigger a kilonova — the ultra-powerful, gold-producing explosion created by colliding neutron stars. Such an arrangement is so vanishingly rare that only about 10 such systems are thought to exist in the entire Milky Way Galaxy. The findings are published today in the journal Nature. 

This unusual system, known as CPD-29 2176, is located about 11,400 light-years from Earth. It was first identified by NASA’s Neil Gehrels Swift Observatory. Later observations with the SMARTS 1.5-meter Telescope allowed astronomers to deduce the orbital characteristics and types of stars that make up this system — a neutron star created by an ultra-stripped supernova and a closely orbiting massive star that is in the process of becoming an ultra-stripped supernova itself.

An ultra-stripped supernova is the end-of-life explosion of a massive star that has had much of its outer atmosphere stripped away by a companion star. This class of supernova lacks the explosive force of a traditional supernova, which would otherwise “kick” a nearby companion star out of the system. 

“The current neutron star would have to form without ejecting its companion from the system. An ultra-stripped supernova is the best explanation for why these companion stars are in such a tight orbit,” said Noel D. Richardson at Embry-Riddle Aeronautical University and lead author of the paper. “To one day create a kilonova, the other star would also need to explode as an ultra-stripped supernova so the two neutron stars could eventually collide and merge.”

As well as representing the discovery of an incredibly rare cosmic oddity, finding and studying kilonova progenitor systems such as this can help astronomers unravel the mystery of how kilonovae form, shedding light on the origin of the heaviest elements in the Universe. 

“For quite some time, astronomers speculated about the exact conditions that could eventually lead to a kilonova,” said NOIRLab astronomer and co-author André-Nicolas Chené. “These new results demonstrate that, in at least some cases, two sibling neutron stars can merge when one of them was created without a classical supernova explosion.” 

Producing such an unusual system, however, is a long and unlikely process. “We know that the Milky Way contains at least 100 billion stars and likely hundreds of billions more. This remarkable binary system is essentially a one-in-ten-billion system,” said Chené. “Prior to our study, the estimate was that only one or two such systems should exist in a spiral galaxy like the Milky Way.” 

Though this system has all the right stuff to eventually form a kilonova, it will be up to future astronomers to study that event. It will take at least one million years for the massive star to end its life as a titanic supernova explosion and leave behind a second neutron star. This new stellar remnant and the pre-existing neutron star will then need to gradually draw together in a cosmic ballet, slowly losing their orbital energy as gravitational radiation. 

When they eventually merge, the resulting kilonova explosion will produce much more powerful gravitational waves and leave behind in its wake a large amount of heavy elements, including silver and gold.

“This system reveals that some neutron stars are formed with only a small supernova kick,” concluded Richardson. “As we understand the growing population of systems like CPD-29 2176 we will gain insight into how calm some stellar deaths may be and if these stars can die without traditional supernovae.”

More information

This research was presented in the paper “A high-mass X-ray binary descended from an ultra-stripped supernova” to appear in the journal Nature. 

The team is composed of Noel D. Richardson (Embry-Riddle Aeronautical University), Clarissa Pavao (Embry-Riddle Aeronautical University), Jan J. Eldridge (University of Auckland), Herbert Pablo (American Association of Variable Star Observers), André-Nicolas Chené (NSF’s NOIRLab/Gemini Observatory), Peter Wysocki (Georgia State University), Douglas R. Gies (Georgia State University), Georges Younes (The George Washington University), and Jeremy Hare (NASA Goddard Space Flight Center).

NSF’s NOIRLab, the US center for ground-based optical-infrared astronomy, operates the International Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), Kitt Peak National Observatory (KPNO), Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and Vera C. Rubin Observatory (operated in cooperation with the Department of Energy’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona. The astronomical community is honored to have the opportunity to conduct astronomical research on Iolkam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence that these sites have to the Tohono O'odham Nation, to the Native Hawaiian community, and to the local communities in Chile, respectively.

This infographic illustrates the evolution of the star system CPD-29 2176, the first confirmed kilonova progenitor. Stage 1, two massive blue stars form in a binary star system. Stage 2, the larger of the two stars nears the end of its life. Stage 3, the smaller of the two stars siphons off material from its larger, more mature companion, stripping it of much of its outer atmosphere. Stage 4, the larger star forms an ultra-stripped supernova, the end-of-life explosion of a star with less of a “kick” than a more normal supernova. Stage 5, as currently observed by astronomers, the resulting neutron star from the earlier supernova begins to siphon off material from its companion, turning the tables on the binary pair. Stage 7, with the loss of much of its outer atmosphere, the companion star also undergoes an ultra-stripped supernova. This stage will happen in about one million years. Stage 7, a pair of neutron stars in close mutual orbit now remain where once there were two massive stars. Stage 8, the two neutron stars spiral into toward each other, giving up their orbital energy as faint gravitational radiation. Stage 9, the final stage of this system as both neutron stars collide, producing a powerful kilonova, the cosmic factory of heavy elements in our Universe.

CREDIT

CTIO/NOIRLab/NSF/AURA/P. Marenfeld

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JOURNAL

Nature

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

A high-mass X-ray binary descended from an ultra-stripped supernova

ARTICLE PUBLICATION DATE

1-Feb-2023

When your supernova’s a dud: Rare binary star features weirdly round orbit, Embry-Riddle researchers report

Peer-Reviewed Publication

EMBRY-RIDDLE AERONAUTICAL UNIVERSITY

 

IMAGE: BY STUDYING THE BINARY STAR SYSTEM CPD-29 2176 (SHOWN HERE), RESEARCHERS ARE UNRAVELING NEW CLUES TO OUR EARLIEST BEGINNINGS, AS STARDUST. SCIENTISTS ESTIMATE THAT THERE ARE PROBABLY ONLY ABOUT 10 SUCH STAR SYSTEMS IN THE GALAXY AT PRESENT. view more 

CREDIT: NOIRLAB/NSF/AURA/J. DA SILVA/SPACEENGINE

After crunching a mountain of astronomy data, Clarissa Pavao, an undergraduate at Embry-Riddle Aeronautical University’s Prescott, Arizona campus, submitted her preliminary analysis. Her mentor’s response was swift and in all-caps. “THERE’S AN ORBIT!” he wrote.

That was when Pavao, a senior Space Physics major, realized she was about to become a part of something big – a paper in the peer-reviewed journal Nature that describes a rare binary star system with uncommon features.

The Nature paper, published on Feb. 1, 2023, and co-authored with Dr. Noel D. Richardson, assistant professor of Physics and Astronomy at Embry-Riddle, describes a twin-star system that is luminous with X-rays and high in mass. Featuring a weirdly circular orbit – an oddity among binaries – the twin system seems to have formed when an exploding star or supernova fizzled out without the usual bang, similar to a dud firecracker.

The binary’s round orbit was a key clue that helped researchers identify the second star in the binary system as a depleted or “ultra-stripped” supernova. Usually, after a star consumes all of its nuclear fuel, its core collapses before exploding into space as a supernova. In this case, Richardson said, “The star was so depleted that the explosion didn’t even have enough energy to kick the orbit into the more typical elliptical shape seen in similar binaries.”

We are Stardust

The binary system’s name sounds like a license plate: CPD-29 2176. Researchers estimate that there are probably only about 10 such star systems in the Galaxy at present. By studying it, they are unraveling new clues to our earliest beginnings, as stardust.

“When we look at these objects, we’re looking backward through time,” explained Pavao. “We get to know more about the origins of the universe, which will tell us where our solar system is headed. As humans, we started out with the same elements as these stars.”

Richardson added that, without binary systems like CPD-29 2176, life on Earth would be very different. “Systems like this are likely to evolve into binary neutron stars, which eventually merge and form heavy elements that get hurled into the universe,” he noted. “Those heavy elements allow us to live the way that we do. For example, most gold was created by stars similar to the supernova relic or neutron star in the binary system that we studied. Astronomy deepens our understanding of the world and our place in it.”

Persistence Pays

The project started when Pavao stopped by Richardson’s office in hopes of scoring a research experience. “I said, `Please give me any research.’” He happened to have data, captured by the Cerro Tololo Interamerican Observatory’s 1.5 meter telescope in Chile, from a bright star known as a Be-type star. The Be star was located at the same location on the sky as another one that had produced a large flash of X-rays. That flash – possibly something called a “soft gamma repeater” – had gotten astronomers’ attention, prompting Richardson and others to request telescope data.

Pavao plotted the spectra of the Be star, but first, she had to clean up the data so they were less noisy. “The telescope looks at a star and it takes in all the light so that you can see the elements that make up this star,” she noted, “but Be stars tend to have discs of matter around them. It’s hard to see directly through all that stuff.”

Persistence paid off: Pavao managed to learn more about data processing and computer coding so that she could analyze the stellar spectra. She and Richardson found one simple line that came from the star and wasn’t influenced by the disc around it. She thought her graph was a scatterplot. Richardson thought otherwise, prompting his all-caps email. After quickly fitting Pavao’s data into a special computer program, he realized they had found an orbit for the star, but it was different than expected. Further data-crunching revealed that one star was indeed tracing a circle around the other one every 60 days or so.

Pavao recalls Richardson saying, “This is not just a simple binary system.”

Collaboration Counts

Enter Jan J. Eldridge of the University of Auckland, a co-author on the Nature paper and a foremost expert on understanding binary star systems and their evolution. At Richardson’s request, Eldridge reviewed thousands of binary star models and found only two that were analogous to the one that he and Pavao were studying.

Eldridge and colleagues then diagramed the life cycle of the two binary system stars, explaining how the supernova relic had puffed up and dumped mass onto the Be star until it began to build up, too. Ultimately, the supernova became a low-mass helium star that exploded, leaving behind a neutron star, but it had already transferred so much of its mass to the Be star that the explosion was lackluster.

“Basically, we found out how the ultra-stripped supernova interacts with the Be star, and how it goes through these weird life-cycle phases,” Pavao explained. “At some point in the future, that Be star will also be a supernova neutron star as the cycle continues. It will become a binary system with two neutron stars, millions of years from now.”

Looking Ahead

A native of Belleville, Illinois, Pavao grew up in a science-focused family. Her father is a computer scientist and her mother is a geologist and amateur astronomer.

During her undergraduate years at Embry-Riddle, Pavao had a chance to complete an undergraduate research experience at the SETI (Search for Extraterrestrial Intelligence) Institute, where she met scientists including Jill Tarter, who was played by actress Jodi Foster in the movie “Contact.”

“It was a life-changing experience,” Pavao said. “Later on in life, I’ll be able to say I went to this observatory and looked for techno-signatures from outer space.” Pavao also credits Richardson with guiding her research and giving her the confidence to succeed. Initially enrolled in a different major, Pavao had the mistaken belief that she was “terrible at math and science” – until she got involved in Richardson’s astronomy project. “He pushes for his students to be on papers,” she noted. “That made a big difference for me.”

With graduation on the horizon next spring, Pavao is evaluating her graduate school options. She’s thinking about a physics focus. “How cool would it be to study dark matter using supercomputers?” she asks.

In addition to Richardson, Pavao and Eldridge, the Nature paper, “A high-mass X-ray binary descended from an ultra-stripped supernova” (Feb. 1, 2023), was co-authored by Herbert Pablo, American Association of Variable Star Observers; André-Nicolas Chené, Gemini Observatory; Peter Wysocki and Douglas R. Gies, CHARA and Georgia State University; Georges Younes, The George Washington University; and Jeremy Hare, NASA Goddard Space Flight Center.

Pavao’s research was supported by Embry-Riddle’s Undergraduate Research Institute and the Arizona Space Grant program. The project also received support from the university’s Faculty Innovative Research in Science and Technology program. Spectroscopy data were collected through NOIR Lab programs 2018B-0137 and 2020A-0054.

The DOI number for this paper is 10.1038/s41586-022-05618-9. Once the embargo has lifted, it will be published by Nature at the following URL: https://www.nature.com/articles/s41586-022-05618-9 

 

 

 

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JOURNAL

Nature

DOI

10.1038/s41586-022-05618-9 

METHOD OF RESEARCH

Imaging analysis

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

A high-mass X-ray binary descended from an ultra-stripped supernova”

ARTICLE PUBLICATION DATE

1-Feb-2023

COI STATEMENT

There is no conflict of interest. Clarissa Pavao’s research was supported by Embry-Riddle’s Undergraduate Research Institute and the Arizona Space Grant program. The project also received support from the university’s Faculty Innovative Research in Science and Technology program. Spectroscopy data were collected through NOIR Lab programs 2018B-0137 and 2020A-0054.

LOOKING GLASS BACK IN TIME
Webb Telescope Captures Countless Galaxies in New Image

Isaac Schultz
Tue, January 31, 2023 at 2:50 PM MST·2 min read

The distant spiral galaxy LEDA 2046648.

The European Space Agency has released its image of the month for January, and it is (perhaps unsurprisingly) a stunning shot from the Webb Space Telescope.

At the bottom of the image is LEDA 2046648, a spiral galaxy over one billion light-years from Earth in the constellation Hercules. Behind LEDA is a field of more distant galaxies, ranging from spiral shapes to pinpricks of light in the distant universe.

Webb launched from French Guiana in December 2021; its scientific observations of the cosmos began in July. Webb has imaged distant galaxies, exoplanets, and even shed new light on worlds in our local solar system.

Though this image was only just released, it was taken during the commissioning process for one of Webb’s instruments, the Near-Infrared Imager and Slitless Spectrograph (NIRISS), according to an ESA release. While NIRISS was focused on a white dwarf—the core remnant of a star—Webb’s Near-Infrared Camera (NIRCam) turned its focus to LEDA 2046648 and its environs in the night sky.

One of Webb’s primary objectives in looking at the distant universe is to better understand how the first stars and galaxies formed. To that end, the telescope is looking at some of the most ancient light in the universe, primarily through its instruments NIRCam and MIRI.

The image does contains hundreds of light sources our eye can perceive, but the infrared data from which the image was formed certainly records many more galaxies.

Webb’s deep field imagery is what enables scientists to see some of the most ancient light in the universe, often capitalizing on gravitational lensing (the magnification of distant light due to the gravitational warping of spacetime) to see particularly ancient sources.

Though this shot of LEDA 2046648 is not a deep field, it evokes a similar feeling: awe, at the huge scale of the cosmos, and (if only briefly) the realization that our minds can only comprehend a fraction of it.

More: Zoom in on Webb Telescope’s Biggest Image Yet

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