Star Light, Star Bright … But Exactly How Bright?

Astronomers use the brightness of a type of exploding star known as a supernova type IA (seen here as bright blue dot to the left of a remote spiral galaxy) to determine the age and expansion rate of the universe. New calibrations of the luminosity of nearby stars, observed by NIST researchers, could help astronomers refine their measurements.
Credit: NASA, ESA, J. DePasquale (STScI), M. Kornmesser and M. Zamani (ESA/Hubble), A. Riess (STScI/JHU) and the SH0ES team, and the Digitized Sky Survey

A picture may be worth a thousand words, but for astronomers, simply recording images of stars and galaxies isn’t enough. To measure the true size and absolute brightness (luminosity) of heavenly bodies, astronomers need to accurately gauge the distance to these objects. To do so, the researchers rely on “standard candles” -- stars whose luminosities are so well known that they act like light bulbs of known wattage. One way to determine a star’s distance from Earth is to compare how bright the star appears in the sky to its luminosity.

But even standard candles need to be calibrated. For more than a decade, scientists at the National Institute of Standards and Technology (NIST) have been working to improve the methods for calibrating standard stars. They observed two nearby bright stars, Vega and Sirius, in order to calibrate their luminosity over a range of visible-light wavelengths. The researchers are now completing their analysis and plan to release the calibration data to astronomers within the next 12 months.

Not all wildlife recovered in lockdowns, new research finds

European Robin Photo credit: Andy Holmes

When the COVID pandemic started, it was a global crisis for humans – but as humans took shelter, reports of wildlife reclaiming what were once human-dominated spaces abounded. But biologists are noticing the patterns were not repeated around the globe.

Last year, a research team led by University of Manitoba conservation biology professor Nicola Koper found that during the lockdowns most birds in Canada and the USA increased in human-dominated areas, such as cities or near roads. New research, however, shows a different story in other parts of the world.

Koper teamed up with the first author Dr. Miya Warrington and other team members to study responses of birds to lockdowns in the United Kingdom, published today in Proceedings of the Royal Society B. Surprisingly, this research showed that while some British birds increased their use of spaces that they share with humans, many species did not. It seems that some of Brits’ favorite lockdown outdoor activities, like visiting parks and hanging out in our backyards, infringed on birds that share our spaces.

“Although I was happy to see people getting out and enjoying nature, I was also worried that some natural spaces would be flooded with people, and we may accidentally be ‘smothering nature with our love’. We may have created a bit too much human pressure on the very places that bring us joy and comfort,” says lead author Miya Warrington.

Astronomers detect hot gas bubble swirling around the Milky Way’s supermassive black hole

This shows a still image of the supermassive black hole Sagittarius A*, as seen by the Event Horizon Collaboration (EHT), with an artist’s illustration indicating where the modelling of the ALMA data predicts the hot spot to be and its orbit around the black hole. 
Credit: EHT Collaboration, ESO/M. Kornmesser (Acknowledgment: M. Wielgus)

Using the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers have spotted signs of a ‘hot spot’ orbiting Sagittarius A*, the black hole at the centre of our galaxy. The finding helps us better understand the enigmatic and dynamic environment of our supermassive black hole.

“We think we're looking at a hot bubble of gas zipping around Sagittarius A* on an orbit similar in size to that of the planet Mercury, but making a full loop in just around 70 minutes. This requires a mind-blowing velocity of about 30% of the speed of light!” says Maciek Wielgus of the Max Planck Institute for Radio Astronomy in Bonn, Germany, who led the study published today in Astronomy & Astrophysics.

The observations were made with ALMA in the Chilean Andes — a radio telescope co-owned by the European Southern Observatory (ESO) — during a campaign by the Event Horizon Telescope (EHT) Collaboration to image black holes. In April 2017 the EHT linked together eight existing radio telescopes worldwide, including ALMA, resulting in the recently released first ever image of Sagittarius A. To calibrate the EHT data, Wielgus and his colleagues, who are members of the EHT Collaboration, used ALMA data recorded simultaneously with the EHT observations of Sagittarius A. To the team's surprise, there were more clues to the nature of the black hole hidden in the ALMA-only measurements.

Gut Microbiomes Help Bears with Very Different Diets Reach the Same Size

Photo credit: National Park Service.

A recent study of the gut microbiome of Alaskan brown bears (Ursus arctos) shows that the microbial life in bears’ guts allows them to achieve comparable size and fat stores while eating widely different diets. The work sheds light on the role of the gut microbiome in supporting health in wild omnivores.

“We think of bears as having simple digestive tracts, so it’s easy to slip into thinking that they therefore have simple gut microbiomes,” says Erin McKenney, co-author of the study and an assistant professor of applied ecology at North Carolina State University. “But this study shows there can be tremendous diversity in the gut microbiomes between individual bears, and that this variation can be very important to the physical condition of these animals.”

“For example, the amount of fat that bears are able to store is absolutely critical to the health of wild populations,” says Grant Hilderbrand, co-author of the study and associate regional director for resources for the National Park Service in Alaska. “If female bears are able to reach levels where 19-20% of their body mass in the autumn is fat, they’ll reproduce. And knowing that they can take different dietary paths to reach those fat levels is a valuable insight.”

For this study, researchers collected fecal samples from 51 adult brown bears in three national parks: Katmai National Park and Preserve, Lake Clark National Park and Preserve, and Gates of the Arctic National Park and Preserve.

How global warming affects astronomical observations

The VLT's Laser Guide Star: A laser beam launched from VLT´s 8.2-metre Yepun telescope crosses the majestic southern sky and creates an artificial star at 90 km altitude in the high Earth´s mesosphere. The Laser Guide Star (LGS) is part of the VLT´s Adaptive Optics system and it is used as reference to correct images from the blurring effect of the atmosphere.
Credit: ESO / G. Hüdepohl atacamaphoto.com

Astronomical observations from ground-based telescopes are sensitive to local atmospheric conditions. Anthropogenic climate change will negatively affect some of these conditions at observation sites around the globe, as a team of researchers led by the University of Bern and the National Centre of Competence in Research (NCCR) PlanetS reports.

The quality of ground-based astronomical observations delicately depends on the clarity of the atmosphere above the location from which they are made. Sites for telescopes are therefore very carefully selected. They are often high above sea level, so that less atmosphere stands between them and their targets. Many telescopes are also built in deserts, as clouds and even water vapor hinder a clear view of the night sky.

A team of researchers led by the University of Bern and the National Centre of Competence in Research (NCCR) PlanetS shows in a study, published in the journal Astronomy & Astrophysics and presented at the Europlanet Science Congress 2022 in Granada, how one of the major challenges of our time – anthropogenic climate change – now even affects our view of the cosmos.

Wildfire smoke is unraveling decades of air quality gains

Over the last decade, PM2.5 from wildfire smoke has increased in much of the U.S., particularly in Western states, but some areas in the South and East have seen modest declines. This map shows the decadal change in smoke PM2.5, meaning the difference in daily average smoke PM2.5 during 2006−2010 compared to 2016−2020.
Image credit: Childs et al. 2022, Environmental Science & Technology

Stanford researchers have developed an AI model for predicting dangerous particle pollution to help track the American West’s rapidly worsening wildfire smoke. The detailed results show millions of Americans are routinely exposed to pollution at levels rarely seen just a decade ago.

Wildfire smoke now exposes millions of Americans each year to dangerous levels of fine particulate matter, lofting enough soot across parts of the West in recent years to erase much of the air quality gains made over the last two decades.

Those are among the findings of a new Stanford University study published Sept. 22 in Environmental Science & Technology that focuses on a type of particle pollution known as PM2.5, which can lodge deep in our lungs and even get into our bloodstream.

Using statistical modeling and artificial intelligence techniques, the researchers estimated concentrations of PM2.5 specifically from wildfire smoke in sharp enough detail to reveal variations within individual counties and individual smoke events from coast to coast from 2006 to 2020.

“We found that people are being exposed to more days with wildfire smoke and more extreme days with high levels of fine particulate matter from smoke,” said lead study author Marissa Childs, who worked on the research as a PhD student in Stanford’s Emmett Interdisciplinary Program in Environment and Resources (E-IPER). Unlike other major pollutant sources, wildfire smoke is considered an “exceptional event” under the Clean Air Act, she explained, “which means an increasing portion of the particulate matter that people are exposed to is unregulated.”

Researchers develop a cobalt-free cathode for lithium-ion batteries

Working with researchers at four U.S. national laboratories, Huolin Xin, UCI professor of physics & astronomy, has found a way to fabricate lithium-ion batteries without using cobalt, a rare, costly mineral extracted under inhumane conditions in Central Africa.
Credit: Steve Zylius / UCI

Researchers at the University of California, Irvine and four national laboratories have devised a way to make lithium-ion battery cathodes without using cobalt, a mineral plagued by price volatility and geopolitical complications.

In a paper published today in Nature, the scientists describe how they overcame thermal and chemical-mechanical instabilities of cathodes composed substantially of nickel – a common substitute for cobalt – by mixing in several other metallic elements.

“Through a technique we refer to as ‘high-entropy doping,’ we were able to successfully fabricate a cobalt-free layered cathode with extremely high heat tolerance and stability over repeated charge and discharge cycles,” said corresponding author Huolin Xin, UCI professor of physics & astronomy. “This achievement resolves long-standing safety and stability concerns around high-nickel battery materials, paving the way for broad-based commercial applications.”

Cobalt is one of the most significant supply chain risks threatening widespread adoption of electric cars, trucks and other electronic devices requiring batteries, according to the paper’s authors. The mineral, which is chemically suited for the purpose of stabilizing lithium-ion battery cathodes, is mined almost exclusively in the Democratic Republic of Congo under abusive and inhumane conditions.

Astronomers Unveil New – and Puzzling – Features of Mysterious Fast Radio Bursts

Artist's conception of Five-hundred-meter Aperture Spherical radio Telescope (FAST) in China.
Credit: Jingchuan Yu

Fast radio bursts (FRBs) are millisecond-long cosmic explosions that each produce the energy equivalent to the sun’s annual output. More than 15 years after the deep-space pulses of electromagnetic radio waves were first discovered, their perplexing nature continues to surprise scientists – and newly published research only deepens the mystery surrounding them.

In the Sept. 21 issue of the journal Nature, unexpected new observations from a series of cosmic radio bursts by an international team of scientists – including UNLV astrophysicist Bing Zhang – challenge the prevailing understanding of the physical nature and central engine of FRBs.

The cosmic FRB observations were made in late spring 2021 using the massive Five-hundred-meter Aperture Spherical radio Telescope (FAST) in China. The team, led by Heng Xu, Kejia Lee, Subo Dong from Peking University, and Weiwei Zhu from the National Astronomical Observatories of China, along with Zhang, detected 1,863 bursts in 82 hours over 54 days from an active fast radio burst source called FRB 20201124A.

“This is the largest sample of FRB data with polarization information from one single source”, said Lee.

Smashing Heavy Nuclei Reveals Proton Size

A model assuming smaller protons & neutrons & a “lumpier” arrangement of these building blocks (left) fits experimental data on the initial energy density in heavy ion collisions better than a model w/ larger protons, neutrons & smoother structure (right)
Image credit: Brookhaven National Laboratory

The nuclei of atoms are made up of protons and neutrons, collectively referred to as nucleons. Nucleons in turn consist of quarks and gluons. Understanding how those inner building blocks are distributed within nuclei can reveal how large protons and neutrons appear when probed at high energy. This work used comparisons between model calculations and new precision data from collisions of heavy ions (containing many protons and neutrons) to access the distribution of gluons and predict the size of the proton.

Identifying and precisely measuring factors that are sensitive to nucleon size will help physicists more accurately describe the quark-gluon plasma (QGP). This is a hot, dense form of nuclear matter created when individual protons and neutrons “melt” in heavy ion collisions, mimicking the conditions of the early universe. This knowledge can eliminate significant uncertainties about the initial state of the produced QGP. Knowing more about the initial state of QGP provides input for the model calculations that scientists use to infer the viscosity and other properties of the QGP. The results also add to measurements of proton size based on the distribution of quarks inside the proton.

Shutting down backup genes leads to cancer remission in mice

Abhinav Achreja, PhD, Research Fellow at the University of Michigan Biomedical Engineering and Deepak Nagrath, Ph.D. Associate Professor of Biomedical Engineering works on ovarian cancer cell research in the bio-engineering lab at the North Campus Research Center (NCRC).
Image credit: Marcin Szczepanski, Michigan Engineering

The way that tumor cells enable their uncontrolled growth is also a weakness that can be harnessed to treat cancer, researchers at the University of Michigan and Indiana University have shown.

Their machine-learning algorithm can identify backup genes that only tumor cells are using so that drugs can target cancer precisely.

“Most cancer drugs affect normal tissues and cells. However, our strategy allows specific targeting of cancer cells.”

Deepak Nagrath

The team demonstrated this new precision medicine approach for treating ovarian cancer in mice. Moreover, the cellular behavior that exposes these vulnerabilities is common across most forms of cancer, meaning the algorithms could provide better treatment plans for a host of malignancies.

“This could revolutionize the precision medicine field because the drug targeting will only affect and kill cancer cells and spare the normal cells,” said Deepak Nagrath, a U-M associate professor of biomedical engineering and senior author of the study in Nature Metabolism. “Most cancer drugs affect normal tissues and cells. However, our strategy allows specific targeting of cancer cells.”