Science
Webb Telescope observes a globular cluster sparkling with separate stars – Phys.org
On June 20, 2022, the James Webb Space Telescope spent just over one hour staring at Messier 92 (M92), a globular cluster 27,000 light-years away in the Milky Way halo. The observation—among the very first science observations undertaken by Webb—is part of Early Release Science (ERS) program 1334, one of 13 ERS programs designed to help astronomers understand how to use Webb and make the most of its scientific capabilities.
NASA spoke with Matteo Correnti from the Italian Space Agency; Alessandro Savino from the University of California, Berkeley; Roger Cohen from Rutgers University; and Andy Dolphin from Raytheon Technologies to find out more about Webb’s observations of M92 and how the team is using the data to help other astronomers. (Last November, Kristen McQuinn talked with NASA about her work on the dwarf galaxy WLM, which is also part of this program.)
Tell us about this ERS program. What are you trying to accomplish?
Alessandro Savino: This particular program is focused on resolved stellar populations. These are large groups of stars like M92 that are very nearby—close enough that Webb can single out the individual stars in the system. Scientifically, observations like these are very exciting because it is from our cosmic neighborhood that we learn a lot of the physics of stars and galaxies that we can translate to objects that we see much farther away.
Matteo Correnti: We’re also trying to understand the telescope better. This project has been instrumental for improving the calibration (making sure all of the measurements are as accurate as possible), for improving the data for other astronomers and other similar projects.
Why did you decide to look at M92 in particular?
Savino: Globular clusters like M92 are very important for our understanding of stellar evolution. For decades they have been a primary benchmark for understanding how stars work, how stars evolve. M92 is a classic globular cluster. It’s close by; we understand it relatively well; it’s one of our references in studies of stellar evolution and stellar systems.
Correnti: Another reason M92 is important is because it is one of the oldest globular clusters in the Milky Way, if not the oldest one. We think M92 is between 12 and 13 billion years old. It contains some of the oldest stars that we can find, or at least that we can resolve and characterize well. We can use nearby clusters like this as tracers of the very ancient universe.
Roger Cohen: We also chose M92 because it is very dense: There are a lot of stars packed together very closely. (The center of the cluster is thousands of times denser than the region around the sun.) Looking at M92 allows us to test how Webb performs in this particular regime, where we need to make measurements of stars that are very close together.
What are the characteristics of a globular cluster that make it useful for studying how stars evolve?
Andy Dolphin: One of the main things is that the bulk of the stars in M92 would have formed at roughly the same time and with roughly the same mix of elements, but with a wide range of masses. So we can get a really good survey of this particular population of stars.
Savino: Also, since the stars all belong to the same object (the same globular cluster, M92), we know they are all about the same distance away from us. That helps us a lot because we know that differences in brightness between the different stars must be intrinsic, instead of just related to how far away they are. It makes the comparison with models much, much easier.
This star cluster has already been studied with the Hubble Space Telescope and other telescopes. What can we see with Webb that we have not seen already?
Cohen: One of the important differences between Webb and Hubble is that Webb operates at longer wavelengths, where very cool, low-mass stars give off most of their light. Webb is well-designed to observe very cool stars. We were actually able to reach down to the lowest mass stars—stars less than 0.1 times the mass of the sun. This is interesting because this is very close to the boundary where stars stop being stars. (Below this boundary are brown dwarfs, which are so low-mass that they’re not able to ignite hydrogen in their cores.)
Correnti: Webb is also a lot faster. To see the very faint low-mass stars with Hubble, you need hundreds of hours of telescope time. With Webb, it takes just a few hours.
Cohen: These observations weren’t actually designed to push very hard on the limits of the telescope. So it’s very encouraging to see that we were still able to detect such small, faint stars without trying really, really hard.
What’s so interesting about these low-mass stars?
Savino: First of all, they are the most numerous stars in the universe. Second, from a theoretical point of view, they are very interesting because they’ve always been very difficult to observe and characterize. Especially stars less than half the mass of the sun, where our current understanding of stellar models is a little more uncertain.
Correnti: Studying the light these low-mass stars emit can also help us better constrain the age of the globular cluster. That helps us better understand when different parts of the Milky Way (like the halo, where M92 is located) formed. And that has implications for our understanding of cosmic history.
It looks like there’s big gap in the middle of the image you captured. What is that and why is it there?
Dolphin: This image was made using Webb’s Near-Infrared Camera (NIRCam). NIRCam has two modules, with a “chip gap” between the two. The center of the cluster is extremely crowded, extremely bright. So that would have limited the usefulness of the data from that region. The position of these images overlaps nicely with Hubble data available already.
One of your main goals was to provide tools for other scientists. What are you particularly excited about?
Dolphin: One of the key resources we developed and have made available to the astronomical community is something called the DOLPHOT NIRCam module. This works with an existing piece of software used to automatically detect and measure the brightness of stars and other unresolved objects (things with a star-like appearance). This was developed for cameras on Hubble. Adding this module for NIRCam (as well as one for NIRISS, another of Webb’s instruments) allows astronomers the same analysis procedure they know from Hubble, with the additional benefit of now being able to analyze Hubble and Webb data in a single pass to get combined-telescope star catalogs.
Savino: This is a really big community service component. It’s helpful for everyone. It’s making analysis much easier.
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On Saturday, the 2023DZ2 will come within a third of the distance from the Earth to the Moon.
A large asteroid will safely zoom between Earth and the Moon on Saturday, a once-in-a-decade event that will be used as a training exercise for planetary defence efforts, according to the European Space Agency.
The asteroid, named 2023 DZ2, is estimated to be 40 to 70 metres (130 to 230 feet) wide, roughly the size of the Parthenon, and big enough to wipe out a large city if it hit our planet.
At 19:49 GMT on Saturday, it will come within a third of the distance from the Earth to the Moon, said Richard Moissl, the head of the ESA’s planetary defence office.
Though that is “very close”, there is nothing to worry about, he told AFP news agency.
Small asteroids fly past every day, but one of this size coming so close to Earth only happens about once every 10 years, he added.
The asteroid will pass 175,000km (109,000 miles) from Earth at a speed of 28,000 kilometres per hour (17,400 miles per hour). The Moon is roughly 385,000km (239,228 miles) away.
An observatory in La Palma, one of Spain’s Canary Islands, first spotted the asteroid on February 27.
Last week, the United Nations-endorsed International Asteroid Warning Network decided it would take advantage of the close look, carrying out a “rapid characterisation” of 2023 DZ2, Moissl said. That means astronomers around the world will analyse the asteroid with a range of instruments such as spectrometers and radars.
The goal is to find out just how much we can learn about such an asteroid in only a week, Moissl said. It will also serve as training for how the network “would react to a threat” possibly heading our way in the future, he added.
The asteroid will again swing past Earth in 2026, but poses no threat of impact for at least the next 100 years – which is how far out its trajectory has been calculated.
Bothwell woman gets experience of a lifetime witnessing natural wonder
Northern Lights outside Newbury. (Photo via Joanna from Bothwell) March 23, 2023.
March 25, 2023 5:40am
A Bothwell woman is thanking her lucky stars for checking off an important item off her bucket list.
Joanna, who didn’t want her last name used, told CK News Today that seeing the Northern Lights or Aurora Borealis so far south Thursday night at around 11 p.m. just outside of Newbury was a bucket list moment achieved.
“It’s actually been on my bucket list for a very long time. Last month I was even looking at flights out to Manitoba hoping that we might get lucky and catch them out there, but I ended up seeing them close to home instead,” said Joanna.
Joanna said she was completely taken by surprise to see such a rare southwestern Ontario sighting of the Northern Lights on her way home.
“Captivating, it was just the beauty of it. We stopped on the side of the road and our mouths dropped just taking it all in. It was captivating and breathtaking, the fact that we may never get this chance to see this, especially on our side of Ontario,” she said.
Joanna said the sighting was phenomenal, amazing, and filled her heart with joy.
“Made a trip out to Banff, Lake Louise in 2021 and found a lot of inner peace. So, since then, I’ve been chasing and checking things off on my bucket list and that being one of them was fantastic,” Joanna added.
She added seeing the Northern Lights up close also gave her a deeper appreciation for how beautiful our planet is.
There were several sightings of the Northern Lights reported dancing across southern Ontario skies on Thursday night.
The National Oceanic and Atmospheric Administration (NOAA) said the Aurora Borealis (Northern Lights) can be seen further south when space weather activity increases and more frequent and larger storms and sub-storms occur.
Northern Lights are the result of accelerated electrons following Earth’s magnetic field to the poles and colliding with oxygen and nitrogen atoms and molecules in the upper atmosphere, according to NOAA.
“In these collisions, the electrons transfer their energy to the atmosphere thus exciting the atoms and molecules to higher energy states. When they relax back down to lower energy states, they release their energy in the form of light. This is similar to how a neon light works,” said NOAA.
NOAA reported a major magnetic storm Thursday night and said during major geomagnetic storms the aurora ovals expand away from the poles so much that aurora can be seen over most of the United States.
The aurora typically forms 80 to 500 kilometres above Earth’s surface.
Science
Bison bone found in Prince Albert, Sask., area points to human life there more than 8,000 years ago
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Community-oriented historian David Rondeau found a bison shoulder blade that is more than 8,000 years old at a cut bank near the North Saskatchewan river in Prince Albert, Sask.
“It’s in itself quite surprising. It’s about a thousand years older than what was previously thought for habitation in our area,” Rondeau, also a consultation co-coordinator for Crutwell Metis Local 66, said.
“The dark lines in the hill, or paleosols, are indicative of human life. They are organic remains from habitation. There is a lot of evidence indicating that this was a large-scale bison processing area.”
The site had been on Rondeau’s radar for years, as he would often discover debitage — material produced during the production of stone tools and weapons — at the surface level.
Artifacts like an ovoid knife found at the site indicate people used to process animals there, removing the hides or flesh, Rondeau said.
Rondeau showed CBC many lithic and bone materials from the site, illustrating the evolution of habitations there. There was debitage material about 2,500 years old found just below the surface, and much older animal remains much further below the ground.
“This site is already telling the history, but there’s no record of it in any history book, and I’m honoured to put this on the map to make it real for the people and children who live here.”
Rondeau suspects the hill could have been a bison jump. He said holding the bone of a bison makes it real for him and the nearby community of Sturgeon Lake First Nation, connecting them with the history.
Near the North Saskatchewan River in Prince Albert, community-oriented historian David Rondeau has found an ancient bison bone among other artifacts. University of Saskatchewan retired professor David Meyer had the bison bone carbon dated and he agrees, this site is very special.
Oldest intact human site in Prince Albert area
David Meyer, professor emeritus of archaeology and anthropology at University of Saskatchewan, inspected the site along with Rondeau last year.
Meyer said the thick layer of old black soil had bits of bison bones sticking out of it and sharp quartz flakes, indicating human presence. He said a piece of the bison shoulder blade was removed and sent for radiocarbon dating at a University of Ottawa laboratory.
“It came back as some 8,200 years old. I knew it was old and was thinking in the 6,000 years range, but this is remarkably old,” he said.
“It’s the oldest intact human occupation area that has been found in the Prince Albert area.”
Meyer said equally old material had also been found along the South Saskatchewan river at St. Louis bridge, 35 kilometres south of Prince Albert, in the past.
Up to 11,000 years ago, the whole central Saskatchewan area was covered with glacial ice. Meyer said it would have become hospitable for human habitation around 10,500 years ago.
He said around 8,000 years ago, a cultural group called Nipawin complex, from the Great Plains, lived in these regions.
“Certainly, these people seemed to have been the first really widespread, well-established societies, and hunter and gatherers of course,” he said.
“They were hunting the older species of bison and buffalo with spear throwing or atlatls [a spear or dart throwing device], as bows and arrows were not yet invented.”
Some atlatl dart points dating 8,500 to 11,000 years have been found close to the Montana border and around southern Saskatchewan. Similar atlatl points have been found at Besnard Lake and Buffalo Narrows in northern Saskatchewan.
“The Prince Albert find will provide important information about that region.”
Rondeau said a geoarcheologist from the University of Calgary is expected to assess the site in the spring. Among other things, she is expected to take samples of soil, ancient pollen and phytoliths, which will illustrate what the landscape was like at that time.
“This is pretty early,” Meyer said of the work being done at the site. “It is quite significant but more needs to be found.”
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