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Astronomers Think They Finally Know The Source of The Milky Way's Cosmic Rays – ScienceAlert

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Roughly a century ago, scientists began to realize that some of the radiation we detect in Earth’s atmosphere is not local in origin.

This eventually gave rise to the discovery of cosmic rays, high-energy protons, and atomic nuclei that have been stripped of their electrons and accelerated to relativistic speeds (close to the speed of light).

However, there are still several mysteries surrounding this strange (and potentially lethal) phenomenon.

This includes questions about their origins and how the main component of cosmic rays (protons) are accelerated to such high velocity.

Thanks to new research led by the University of Nagoya, scientists have quantified the amount of cosmic rays produced in a supernova remnant for the first time.

This research has helped resolve a 100-year mystery and is a major step towards determining precisely where cosmic rays come from.

While scientists theorize that cosmic rays originate from many sources – our Sun, supernovae, gamma-ray bursts (GRBs), and Active Galactic Nuclei (aka. quasars) – their exact origin has been a mystery since they were first discovered in 1912.

Similarly, astronomers have theorized that supernova remnants (the after-effects of supernova explosions) are responsible for accelerating them to nearly the speed of light.

As they travel through our galaxy, cosmic rays play a role in the chemical evolution of the interstellar medium (ISM). As such, understanding their origin is critical to understanding how galaxies evolve.

In recent years, improved observations have led some scientists to speculate that supernova remnants give rise to cosmic rays because the protons they accelerate interact with protons in the ISM to create very high-energy (VHE) gamma rays.

However, gamma-rays are also produced by electrons that interact with photons in the ISM, which can be in the form of infrared photons or radiation from the Cosmic Microwave Background (CMB). Therefore, determining which source is greater is paramount to determining the origin of cosmic rays.

Hoping to shed light on this, the research team – which included members from Nagoya University, the National Astronomical Observatory of Japan (NAOJ), and the University of Adelaide, Australia – observed the supernova remnant RX J1713.7?3946 (RX J1713).

The key to their research was the novel approach they developed to quantify the source of gamma-rays in interstellar space.

Past observations have shown that the intensity of VHE gamma-rays caused by protons colliding with other protons in the ISM is proportional to the interstellar gas density, which is discernible using radio-line imaging.

On the other hand, gamma-rays caused by the interaction of electrons with photons in the ISM are also expected to be proportional to the intensity of nonthermal X-rays from electrons.

For the sake of their study, the team relied on data obtained by the High Energy Stereoscopic System (HESS), a VHE gamma-ray observatory located in Namibia (and operated by the Max Planck Institute for Nuclear Physics).

They then combined this with X-ray data obtained by the ESA’s X-ray Multi-Mirror Mission (XMM-Newton) observatory and data on the distribution of gas in the interstellar medium.

They then combined all three data sets and determined that protons account for 67 ± 8 percent of cosmic rays while cosmic-ray electrons account for 33 ± 8 percent – roughly a 70/30 split.

These findings are groundbreaking since they are the first time that the possible origins of cosmic rays have been quantified. They also constitute the most definitive evidence to date that supernova remnants are the source of cosmic rays.

These results also demonstrate that gamma-rays from protons are more common in gas-rich interstellar regions, whereas those caused by electrons are enhanced in the gas-poor regions.

This supports what many researchers have predicted, which is that the two mechanisms work together to influence the evolution of the ISM. 

Said Emeritus Professor Yasuo Fukui, who was the study’s lead author: “This novel method could not have been accomplished without international collaborations. [It] will be applied to more supernova remnants using the next-generation gamma-ray telescope CTA (Cherenkov Telescope Array) in addition to the existing observatories, which will greatly advance the study of the origin of cosmic rays.”

In addition to leading this project, Fukui has been working to quantify interstellar gas distribution since 2003 using the NANTEN radio telescope at the Las Campanas Observatory in Chile and the Australia Telescope Compact Array.

Thanks to Professor Gavin Rowell and Dr. Sabrina Einecke of the University of Adelaide (co-authors on the study) and the H.E.S.S. team, the spatial resolution and sensitivity of gamma-ray observatories have finally reached the point where it is possible to draw comparisons between the two.

Meanwhile, co-author Dr. Hidetoshi Sano of the NAOJ led the analysis of archival datasets from the XMM-Newton observatory. In this respect, this study also shows how international collaborations and data-sharing are enabling all kinds of cutting-edge research.

Along with improved instruments, improved methods and greater opportunities for cooperation are leading to an age where astronomical breakthroughs are becoming a regular occurrence!

This article was originally published by Universe Today. Read the original article.

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Bird reports rose during lockdowns | Cornell Chronicle – Cornell Chronicle

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Around 80% of bird species examined in a new study were reported in greater numbers in human-altered habitats during pandemic lockdowns, according to new research based on data from the eBird program at the Cornell Lab of Ornithology.

In the paper, “Reduced Human Activity During COVID-19 Alters Avian Land Use Across North America,” published Sept. 22 in Science Advances, researchers compared online eBird observations from the United States and Canada from before and during the pandemic. They focused on areas within about 100 km of urban areas, major roads, and airports.

Vast amounts of data from a likewise vast geographic area were vital for this study. The researchers used more than 4 million eBird observations of 82 bird species from across Canada and the U.S.

“A lot of species we really care about became more abundant in human landscapes during the pandemic,” said study senior author Nicola Koper of the University of Manitoba, which led the research. “I was blown away by how many species were affected by decreased traffic and activity during lockdowns.”

Reports of bald eagles increased in cities with the strongest lockdowns. Ruby-throated hummingbirds were three times more likely to be reported within a kilometer of airports than before the pandemic. Barn swallows, a threatened species in Canada, were reported more often within a kilometer of roads than before the pandemic.

A few species decreased their use of human-altered habitat during the pandemic. Red-tailed hawk reports decreased near roads, perhaps because there was less roadkill when traffic declined. But far more species had increased counts in these human-dominated landscapes.

The authors filtered pandemic and pre-pandemic eBird reports so that the final data sets had the same characteristics, such as location, number of lists, and level of birdwatcher effort.

“We also needed to be aware of the detectability issue,” said co-author Alison Johnston, assistant director of the Center for Avian Population Studies and Ecological Data in the Lab of Ornithology. “Were species being reported in higher numbers because people could finally hear the birds without all the traffic noise, or was there a real ecological change in the numbers of birds present?”

The study tested whether better detectability might be a factor in the larger bird numbers reported. If it was, the scientists expected that to be more noticeable for smaller birds, which are harder to detect beneath traffic noise. However, effects were noticed across many species, from hawks to hummingbirds, suggesting that the increased numbers were not only caused by increased detectability in the quieter environments.

“Having so many people in North America and around the world paying attention to nature has been crucial to understanding how wildlife react to our presence,” says lead author Michael Schrimpf, a postdoctoral fellow at the University of Manitoba. “Studies such as this one rely on volunteer birdwatchers, so if you enjoy watching wildlife, there are many projects out there, like eBird and iNaturalist, that can use your help.”

The study was funded by Natural Sciences and Engineering Research Council of Canada with in-kind support provided by Environment and Climate Change Canada and the Cornell Lab of Ornithology.

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SpaceX Crew Dragon cupola provides awe-inspiring view of the Earth from space – Californianewstimes.com

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Holy Molly.

SpaceX

Give a few seconds (or a minute or two if needed) to startle and gaze at the Earth’s scenery from the recently launched SpaceX Crew Dragon above.

on Wednesday, As part of the Inspiration4 mission, four civilians were blown up in a three-day orbital stay.Tied to the SpaceX Crew Dragon with one of the upgrades: Cupola. The transparent dome at the top of the Dragon Capsule provides the Inspiration 4 crew with the best views of the Earth that up-and-coming astronauts can dream of. This is the first time a cupola has been installed on a dragon. Dragons typically carry astronauts and cargo to the ISS, with docking ports at the top instead of windows.

A short video posted to the SpaceX Twitter account hours after the launch shows the cupola’s transparent dome against the Earth, which is a pale blue marble.

As the Crew Dragon orbits from a height of 585 kilometers (more than 360 miles), our planet is exposed to the sun and slowly roams around the orbs.

Inspiration 4’s crew (commander Jared Isaacman, doctor’s assistant, childhood cancer survivor Haley Arseno, aerospace engineer Chris Sembroski, African-American geology professor Sian Proctor) are in orbit for three days. Ride and stare at the cupola and the earth.

And did you say that the cupola is right next to the dragon’s toilet? Yeah, the view of the earth should be visible from the crew dragon’s bathroom. Isaacman told insiders Toilets are one of the few places where you can separate yourself from others with privacy curtains and have the best toilet windows of mankind. “When people inevitably have to use the bathroom, they will see one view of hell,” he said.

Astronauts who have been to space often talk about a phenomenon called the “overview effect.” Looking at the planet from above, the idea is that the way we think about the planet and the mass of humankind that depends on it will change. There may be a lot of revelation at the end of the Inspiration 4 journey, as I don’t know if they thought of it while sitting in the can.

The mission is the first mission to take off from the Florida coast on Wednesday night and be launched with four civilians. It is expected to return to Earth on Saturday and land in the Atlantic Ocean.

SpaceX Crew Dragon cupola provides awe-inspiring view of the Earth from space Source link SpaceX Crew Dragon cupola provides awe-inspiring view of the Earth from space

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Oldest human footprints in North America found in New Mexico – Al Jazeera English

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Fossilised footprints dating 23,000 years push back the known date the continent was colonised by thousands of years.

Footprints dating back 23,000 years have been discovered in the United States, suggesting humans settled North America long before the end of the last Ice Age, according to researchers.

The findings announced on Thursday push back the date at which the continent was colonised by its first inhabitants by thousands of years.

The footprints were left in mud on the banks of a long-since dried up lake, which is now part of a New Mexico desert.

Sediment filled the indentations and hardened into rock, protecting evidence of our ancient relatives, and giving scientists a detailed insight into their lives.

The first footprints were found in a dry lake bed in White Sands National Park in 2009. Scientists at the United States Geological Survey recently analysed seeds stuck in the footprints to determine their approximate age, ranging from 22,800 to 21,130 years ago.

“Many tracks appear to be those of teenagers and children; large adult footprints are less frequent,” write the authors of the study published in the American journal Science.

“One hypothesis for this is the division of labour, in which adults are involved in skilled tasks whereas ‘fetching and carrying’ are delegated to teenagers.

“Children accompany the teenagers, and collectively they leave a higher number of footprints.”

Researchers also found tracks left by mammoths, prehistoric wolves, and even giant sloths, which appear to have been approximately at the same time as the humans visited the lake.

Historic findings

The Americas were the last continent to be reached by humanity.

For decades, the most commonly accepted theory has been that settlers came to North America from eastern Siberia across a land bridge – the present-day Bering Strait.

From Alaska, they headed south to kinder climes.

Archaeological evidence, including spearheads used to kill mammoths, has long suggested a 13,500-year-old settlement associated with so-called Clovis culture – named after a town in New Mexico.

This was considered the continent’s first civilisation, and the forerunner of groups that became known as Native Americans.

However, the notion of Clovis culture has been challenged over the past 20 years, with new discoveries that have pushed back the age of the first settlements.

Generally, even this pushed-back estimate of the age of the first settlements had not been more than 16,000 years, after the end of the so-called “last glacial maximum” – the period when ice sheets were at their most widespread.

This episode, which lasted until about 20,000 years ago, is crucial because it is believed that with ice covering much of the northern parts of the continent, human migration from Asia into North America and beyond would have been very difficult.

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