(Press-News.org) New findings published this week in Physical Review Letters suggest that carbon, oxygen, and hydrogen cosmic rays travel through the galaxy toward Earth in a similar way, but, surprisingly, that iron arrives at Earth differently. Learning more about how cosmic rays move through the galaxy helps address a fundamental, lingering question in astrophysics: How is matter generated and distributed across the universe?
"So what does this finding mean?" asks John Krizmanic, a senior scientist with UMBC's Center for Space Science and Technology (CSST). "These are indicators of something interesting happening. And what that something interesting is we're going to have to see."
Cosmic rays are atomic nuclei--atoms stripped of their electrons--that are constantly whizzing through space at nearly the speed of light. They enter Earth's atmosphere at extremely high energies. Information about these cosmic rays can give scientists clues about where they came from in the galaxy and what kind of event generated them.
An instrument on the International Space Station (ISS) called the Calorimetric Electron Telescope (CALET) has been collecting data about cosmic rays since 2015. The data include details such as how many and what kinds of atoms are arriving, and how much energy they're arriving with. The American, Italian, and Japanese teams that manage CALET, including UMBC's Krizmanic and postdoc Nick Cannady, collaborated on the new research.
Iron on the move
Cosmic rays arrive at Earth from elsewhere in the galaxy at a huge range of energies--anywhere from 1 billion volts to 100 billion billion volts. The CALET instrument is one of extremely few in space that is able to deliver fine detail about the cosmic rays it detects. A graph called a cosmic ray spectrum shows how many cosmic rays are arriving at the detector at each energy level. The spectra for carbon, oxygen, and hydrogen cosmic rays are very similar, but the key finding from the new paper is that the spectrum for iron is significantly different.
There are several possibilities to explain the differences between iron and the three lighter elements. The cosmic rays could accelerate and travel through the galaxy differently, although scientists generally believe they understand the latter, Krizmanic says.
"Something that needs to be emphasized is that the way the elements get from the sources to us is different, but it may be that the sources are different as well," adds Michael Cherry, physics professor emeritus at Louisiana State University (LSU) and a co-author on the new paper. Scientists generally believe that cosmic rays originate from exploding stars (supernovae), but neutron stars or very massive stars could be other potential sources.
An instrument like CALET is important for answering questions about how cosmic rays accelerate and travel, and where they come from. Instruments on the ground or balloons flown high in Earth's atmosphere were the main source of cosmic ray data in the past. But by the time cosmic rays reach those instruments, they have already interacted with Earth's atmosphere and broken down into secondary particles. With Earth-based instruments, it is nearly impossible to identify precisely how many primary cosmic rays and which elements are arriving, plus their energies. But CALET, being on the ISS above the atmosphere, can measure the particles directly and distinguish individual elements precisely.
Iron is a particularly useful element to analyze, explains Cannady, a postdoc with CSST and a former Ph.D. student with Cherry at LSU. On their way to Earth, cosmic rays can break down into secondary particles, and it can be hard to distinguish between original particles ejected from a source (like a supernova) and secondary particles. That complicates deductions about where the particles originally came from.
"As things interact on their way to us, then you'll get essentially conversions from one element to another," Cannady says. "Iron is unique, in that being one of the heaviest things that can be synthesized in regular stellar evolution, we're pretty certain that it is pretty much all primary cosmic rays. It's the only pure primary cosmic ray, where with others you'll have some secondary components feeding into that as well."
"Made of stardust"
Measuring cosmic rays gives scientists a unique view into high-energy processes happening far, far away. The cosmic rays arriving at CALET represent "the stuff we're made of. We are made of stardust," Cherry says. "And energetic sources, things like supernovas, eject that material from their interiors, out into the galaxy, where it's distributed, forms new planets, solar systems, and... us."
"The study of cosmic rays is the study of how the universe generates and distributes matter, and how that affects the evolution of the galaxy," Krizmanic adds. "So really it's studying the astrophysics of this engine we call the Milky Way that's throwing all these elements around."
A global effort
The Japanese space agency launched CALET and today leads the mission in collaboration with the U.S. and Italian teams. In the U.S., the CALET team includes researchers from LSU; NASA Goddard Space Flight Center; UMBC; University of Maryland, College Park; University of Denver; and Washington University.The new paper is the fifth from this highly successful international collaboration published in PRL, one of the most prestigious physics journals.
CALET was optimized to detect cosmic ray electrons, because their spectrum can contain information about their sources. That's especially true for sources that are relatively close to Earth in galactic terms: within less than one-thirtieth the distance across the Milky Way. But CALET also detects the atomic nuclei of cosmic rays very precisely. Now those nuclei are offering important insights about the sources of cosmic rays and how they got to Earth.
"We didn't expect that the nuclei - the carbon, oxygen, protons, iron - would really start showing some of these detailed differences that are clearly pointing at things we don't know," Cherry says.
The latest finding creates more questions than it answers, emphasizing that there is still more to learn about how matter is generated and moves around the galaxy. "That's a fundamental question: How do you make matter?" Krizmanic says. But, he adds, "That's the whole point of why we went in this business, to try to understand more about how the universe works."
Just as the skeleton and muscles move the human body and hold its shape, all the cells of the body are stabilised and moved by a cellular skeleton. Unlike our skeleton, this cellular skeleton is a very dynamic structure, constantly changing and renewing itself. It consists of different types of protein filaments, which include intermediate filaments and microtubules. Now, a research team from the University of Göttingen is the first to succeed in observing a direct interaction between microtubules and intermediate filaments outside the cell, and also in quantitatively measuring this interaction. The results of the study were published in Nature Communications.
Microtubules are dynamic filaments ...
New research reveals how key proteins interact to regulate the body's response to stress
Targeting these proteins may help treat or prevent stress-related psychiatric disorders
The biological mechanisms behind stress-related psychiatric conditions, including major depressive disorder and post-traumatic stress disorder (PTSD), are poorly understood.
New research now details the interplay between proteins involved in controlling the body's stress response and points to potential therapeutic targets when this response goes awry. The study, which was conducted by an international team led by investigators at McLean Hospital, appears in ...
BOSTON - Researchers from Massachusetts General Hospital (MGH) have discovered a biological mechanism that transforms cells exposed to carcinogens from environmental factors like smoking and ultraviolet light into immunogenic cells that can be harnessed therapeutically to fight treatment-resistant cancers. As reported in Science Advances, that mechanism involves spurring the release of small proteins known as chemokines which, in turn, recruit antitumor immune cells (CD8+ T cells) to the tumor site to block metastasis, potentially enhancing the effectiveness of a new generation of immunotherapies.
CHICAGO --- Scientists have long known the brain's hippocampus is crucial for long-term memory. Now a new Northwestern Medicine study has found the hippocampus also plays a role in short-term memory and helps guide decision-making.
The findings shed light on how the hippocampus contributes to memory and exploration, potentially leading to therapies that restore hippocampal function, which is impacted in memory-related aging and neurodegenerative diseases such as dementia, the study authors said.
In the study, scientists monitored participants' brain activity and tracked their eye movements while looking at different complex pictures. The scientists discovered ...
Birds build nests to keep eggs and baby nestlings warm during cool weather, but also make adjustments in nest insulation in such a way the little ones can keep cool in very hot conditions. Mammals, such as rabbits or groundhogs, sleep or hibernate in underground burrows that provide stable, moderate temperatures and avoid above-ground conditions that often are far more extreme outside the burrow.
Michael Dillon, an associate professor in the University of Wyoming Department of Zoology and Physiology, was part of a research group that examined animals' ability to respond to climate change likely depends on how well they modify their habitats, ...
BIRMINGHAM, Ala. - A comprehensive health-screening program in rural northern KwaZulu-Natal, South Africa, has found a high burden of undiagnosed or poorly controlled non-communicable diseases, according to a study published in The Lancet Global Health.
Researchers found that four out of five women over the age of 30 were living with a chronic health condition, and that the HIV-negative population and older people -- especially those over 50 -- bore the higher burden of undiagnosed or poorly controlled non-communicable diseases such as diabetes and hypertension.
The study was co-led by Emily Wong, M.D., a resident faculty member at the Africa Health ...
Irvine, CA - June 18, 2021 - A new study paves the way for the development of next generation therapeutics for the prevention and treatment of Clostridioides difficile infection (CDI), the most frequent cause of healthcare-acquired gastrointestinal infections and death in developed countries.
Published today in Nature Communications, the study reveals the first 3D structure of the Clostridioides difficile toxin B (TcdB) in complex with chondroitin sulfate proteoglycan 4 (CSPG4), a human receptor. The study was co-led by senior author Rongsheng Jin, PhD, a professor in the Department of Physiology & Biophysics at the University of California, Irvine, School of Medicine, and Min Dong, PhD, an associate professor at Harvard Medical School.
"TcdB is one of two homologous C. ...
June 18, 2021 - An experimental artificial heart includes an autoregulation control mechanism, or Auto-Mode, that can adjust to the changing needs of patients treated for end-stage heart failure. Outcomes in the first series of patients managed with the new heart replacement pump in Auto-Mode are presented in the ASAIO Journal, official journal of the American Society for Artificial Internal Organs. The journal is published in the Lippincott portfolio by Wolters Kluwer.
The study reports on the response to "pressure sensor-based autoregulation of blood flow" in ten patients for up to two years after implantation of the Carmat Total Artificial ...
The visual thalamus is classically known to relay visual stimuli coming from the retina to the cerebral cortex. Researchers from the Max Planck Institute of Neurobiology now show that although neurons in the mouse visual thalamus connect to both eyes, they establish strong functional connections only with one retina. These results settle partly contradictory results of earlier studies and demonstrate how important it can be to complement structural data with functional analyses.
We have two eyes, but perceive the tree in front of us only once. Our brain therefore has the complicated task of combining the information of both eyes in a meaningful way. To do so, visual stimuli first travel from the retina via so-called ganglion cells to the visual thalamus. There, the information does end up ...
June 18, 2021 - At least so far, the currently limited research base does not establish that cannabis has additional adverse effects on brain development or functioning in adolescents or young adults with attention-deficit/hyperactivity disorder (ADHD), concludes a review in the July/August issue of Harvard Review of Psychiatry. The journal is published in the Lippincott portfolio by Wolters Kluwer.
While ADHD is clinically defined to have impairments in cognitive functioning, cannabis use by itself is also associated with cognitive impairments: "[T]he evidence to date does not clearly support either an addictive effect or an interaction - whether protective ...