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Challenging Our Understanding of the Universe: Astronomers Discover an Enigmatic Cosmic Explosion

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Artist’s conception of a gamma-ray burst caused by the violent collision of two massive neutron stars, following their inspiraling danse macabre. In addition to high-energy radiation and matter spewed out in a narrow jet, the event is thought to be the Universe’s main factory of heavy elements, including gold and platinum. Credit: A. Simonnet (Sonoma State University) and Goddard Space Flight Center

 

Gamma-ray bursts are the most intense explosions in the universe and are typically caused by the collapse of stars or the collision of compact stellar remnants. However, a recent discovery has challenged this understanding, as it does not fit into either of these categories. Astronomers from the Niels Bohr Institute were instrumental in this study, which has the potential to revise current theories about these powerful events.

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Daniele Bjørn Malesani was carrying out a routine follow-up observation of a gamma-ray burst, named GRB 211211A, using the Nordic Optical Telescope on the Canary island La Palma. A standard procedure after having received the text message that was automatically triggered by the spacecraft “Neil Gehrels Swift Observatory” which monitors the sky for gamma-ray bursts.

 

But something wasn’t quite right…

Hubble Space Telescope View of the Location of the Gamma Ray Bursts GRB 211211A and Its Surroundings

Hubble Space Telescope view of the location of the gamma-ray bursts GRB 211211A and its surroundings. The zoom-in shows the afterglow of the burst, as observed with the Gemini North telescope on Hawaii. The binary system causing the burst was likely ejected in the past from the big, bluish galaxy on its left. Credit: International Gemini Observatory/NOIRLab/NSF/AURA/M. Zamani; NASA/ESA

Malesani is an astronomer at Radboud University in the Netherlands and a guest researcher at the Cosmic Dawn Center in Copenhagen. He expertizes in gamma-ray bursts, the most energetic explosions in the Universe.

 

But to understand what wasn’t right, let’s first have a look at what is a “gamma-ray burst”:

As bright as the Universe itself

Gamma-ray bursts are brief and ultra-bright flashes of the most energetic form of light, gamma rays. Mostly detected in the very distant Universe, they generally come in two categories which are thought to arise from two different physical scenarios:

“Long” bursts typically last from a few seconds to several minutes but are often accompanied by a longer-lasting afterglow of less energetic light. They are found in the most star-forming regions of galaxies and are thought to be the result of a massive star that collapses to a compact <span class=”glossaryLink” aria-describedby=”tt” data-cmtooltip=”

neutron star
A neutron star is the collapsed core of a large (between 10 and 29 solar masses) star. Neutron stars are the smallest and densest stars known to exist. Though neutron stars typically have a radius on the order of just 10 – 20 kilometers (6 – 12 miles), they can have masses of about 1.3 – 2.5 that of the Sun.

” data-gt-translate-attributes=”[“attribute”:”data-cmtooltip”, “format”:”html”]”>neutron star or a <span class=”glossaryLink” aria-describedby=”tt” data-cmtooltip=”

black hole
A black hole is a place in space where the gravitational field is so strong that not even light can escape it. Astronomers classify black holes into three categories by size: miniature, stellar, and supermassive black holes. Miniature black holes could have a mass smaller than our Sun and supermassive black holes could have a mass equivalent to billions of our Sun.

” data-gt-translate-attributes=”[“attribute”:”data-cmtooltip”, “format”:”html”]”>black hole, ejecting its outer parts in an immense explosion, similar to a supernova.

Nordic Optical Telescope

The Nordic Optical Telescope on the 2400 meters high mountain top Roche de los Muchachos in La Palma. Credit: Peter Laursen (Cosmic Dawn Center)

 

“Short” bursts are even more fleeting, with typical durations of 1/10 to 1 second. They are often seen offset from the galactic centers, or even outside galaxies. The prevailing theory is that they are the outcome of two massive stars orbiting each other in a “binary” system. At some point, they explode as supernovae, kicking them out of their host galaxy. Eventually, however, the two objects will spiral in and merge, resulting in a gamma-ray burst.

In both cases, the energy released is mind-blowing: At their peak, they can shine as brightly as all the stars in the observable Universe combined (assuming that they emit light equally in all directions; in reality, they are likely somewhat less bright but emit most of their light in narrow jets, where we just happen to lie in this direction).

The enigmatic gamma-ray bursts

Gamma-ray bursts were first discovered in 1967 by the Vela satellite, built to monitor the sky for possible tests of nuclear weapons, which would be a violation of the 1963 Nuclear Test Ban Treaty. First thought to originate from nearby sources within our own galaxy, more sensitive space observatories revealed, in the 1990s, that they must come from far outside the <span class=”glossaryLink” aria-describedby=”tt” data-cmtooltip=”

Milky Way
The Milky Way is the galaxy that contains our Solar System, and is named for its appearance from Earth. It is a barred spiral galaxy that contains an estimated 100-400 billion stars and has a diameter between 150,000 and 200,000 light-years.

” data-gt-translate-attributes=”[“attribute”:”data-cmtooltip”, “format”:”html”]”>Milky Way, distributed over the whole Universe.

The transient nature of the bursts made them difficult to study, but from the late 1990s, astronomers have been able to detect also their less energetic afterglow, from X-rays to optical light, to the infrared, helping to establish a theory of their origin.

 

Gamma-ray bursts come in two versions, “short” and “long”, which have, until now, been thought to arise from two different physical mechanisms, namely the merging of two compact objects, and the collapse of a massive star, respectively. With the new observations, this theory is now being challenged.

Mixed signals

So what was the issue with Malesani’s burst, GRB 211211A? Well, it seemed to fit in neither, or perhaps both, of these categories. “The observations showed that the burst originated outside of a galaxy typical for hosting short bursts. But rather than being a millisecond or a few seconds, this beast lasted for almost a minute,” Malesani says.

The peculiar event prompted an international team of astronomers, led by Jillian Rastinejad of <span class=”glossaryLink” aria-describedby=”tt” data-cmtooltip=”

Northwestern University
Established in 1851, Northwestern University (NU) is a private research university based in Evanston, Illinois, United States. Northwestern is known for its McCormick School of Engineering and Applied Science, Kellogg School of Management, Feinberg School of Medicine, Pritzker School of Law, Bienen School of Music, and Medill School of Journalism.&nbsp;

” data-gt-translate-attributes=”[“attribute”:”data-cmtooltip”, “format”:”html”]”>Northwestern University (USA), to begin an intensive campaign to study this surprising object. These efforts led to the completely unexpected discovery of a so-called kilonova, the smoking-gun proof of the collision of two neutron stars, or a neutron star and a black hole.

Binary neutron star mergers are widely considered the progenitors of short gamma-ray bursts. Why this one was instead followed by a long burst puzzled the astronomers.

 

Luca Izzo, an astronomer at the DARK research section at the Niels Bohr Institute, participated in the study. He comments: “Gamma-ray bursts can show a variety of behaviors, but the distinction between long and short events has been clearly established since the 1990s and is considered one of the pillars in the field. This finding caught us really by surprise.”

A new engine for making gold?

Kilonovae are thought to be the main mechanism for creating heavy elements such as the precious silver, gold, and platinum, the radioactive plutonium and uranium, as well as many others. As always in physics, definite proof that a kilonova is responsible for the long gamma-ray burst does not exist.

When the astronomers nevertheless are confident in their interpretation, it is due to several circumstances. Johan Fynbo, professor at the Cosmic Dawn Center and partaker in the study, explains:

“The afterglow of the burst showed colors and features that are consistent with a kilonova, and which haven’t been seen for any other types of objects. Moreover, we would not expect to see a collapsing star outside of a galaxy, since traveling this far takes hundreds of millions of years, while massive stars collapse on timescales less than 10 million years.”

 

But in principle, GRB 211211A could be a collapsar inside a faint or dusty, undetected galaxy, although the Hubble images are indeed very deep and ought to have seen this. “Follow-up observations with the more sensitive <span class=”glossaryLink” aria-describedby=”tt” data-cmtooltip=”

ALMA
The Atacama Large Millimeter/submillimeter Array (ALMA) is the largest ground-based facility for observations in the millimeter/submillimeter regime in the world. ALMA comprises 66 high-precision dish antennas of measuring either 12 meters across or 7 meters across and spread over distances of up to 16 kilometers. It is an international partnership between Europe, the United States, Japan, and the Republic of Chile.

” data-gt-translate-attributes=”[“attribute”:”data-cmtooltip”, “format”:”html”]”>ALMA radio telescopes in Chile, or the <span class=”glossaryLink” aria-describedby=”tt” data-cmtooltip=”

James Webb Space Telescope
The James Webb Space Telescope (JWST or Webb) is an orbiting infrared observatory that will complement and extend the discoveries of the Hubble Space Telescope. It covers longer wavelengths of light, with greatly improved sensitivity, allowing it to see inside dust clouds where stars and planetary systems are forming today as well as looking further back in time to observe the first galaxies that formed in the early universe.

” data-gt-translate-attributes=”[“attribute”:”data-cmtooltip”, “format”:”html”]”>James Webb Space Telescope, would be able to settle this issue,” Fynbo remarks.

If the interpretation turns out to be correct, it not only opens up for an exciting new mechanism for kilonovae to form heavy elements. It is also a strong motivation for looking for new kilonovae at the position of long bursts.

“Kilonovae are a relatively new and unexplored phenomenon to us; to this day, we have only detected a few,” explains Daniele Bjørn Malesani. “Because we didn’t expect them to be associated with long bursts, we have not been looking for them there. But now we know that Nature is more resourceful than we previously thought.”

From a previous study in 2006, the three astronomers had a hint that colliding neutron stars might be able to keep their engines active for longer than just a few seconds. But without a kilonova detection, the evidence had been confusing. One theory is that the collapsed neutron stars may spin so fast — at a significant fraction of the speed of light — that centrifugal forces can sustain the merged object for a little while and postpone its gloomy fate.

 

Future observations of more long bursts from kilonovae will teach us more about this exciting phenomenon.

Reference: “A kilonova following a long-duration gamma-ray burst at 350 Mpc” by Jillian C. Rastinejad, Benjamin P. Gompertz, Andrew J. Levan, Wen-fai Fong, Matt Nicholl, Gavin P. Lamb, Daniele B. Malesani, Anya E. Nugent, Samantha R. Oates, Nial R. Tanvir, Antonio de Ugarte Postigo, Charles D. Kilpatrick, Christopher J. Moore, Brian D. Metzger, Maria Edvige Ravasio, Andrea Rossi, Genevieve Schroeder, Jacob Jencson, David J. Sand, Nathan Smith, José Feliciano Agüí Fernández, Edo Berger, Peter K. Blanchard, Ryan Chornock, Bethany E. Cobb, Massimiliano De Pasquale, Johan P. U. Fynbo, Luca Izzo, D. Alexander Kann, Tanmoy Laskar, Ester Marini, Kerry Paterson, Alicia Rouco Escorial, Huei M. Sears and Christina C. Thöne, 7 December 2022, Nature.
DOI: 10.1038/s41586-022-05390-w

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Asteroid's sudden flyby shows blind spot in planetary threat detection – The Globe and Mail

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NASA revealed an asteroid, about the size of a truck, was discovered mere days before it passed Earth on Jan. 26. This diagram made available by NASA shows the asteroid’s estimated trajectory in red, affected by the earth’s gravity, and the orbit of geosynchronous satellites, in green.The Associated Press

The discovery of an asteroid the size of a small shipping truck mere days before it passed Earth on Thursday, albeit one that posed no threat to humans, highlights a blind spot in our ability to predict those that could actually cause damage, astronomers say.

NASA for years has prioritized detecting asteroids much bigger and more existentially threatening than 2023 BU, the small space rock that streaked by 2,200 miles (3,500 kilometres) from the Earth’s surface, closer than some satellites. If bound for Earth, it would have been pulverized in the atmosphere, with only small fragments possibly reaching land.

But 2023 BU sits on the smaller end of a size group, asteroids 5-to-50 metres in diameter, that also includes those as big as an Olympic swimming pool. Objects that size are difficult to detect until they wander much closer to Earth, complicating any efforts to brace for one that could impact a populated area.

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The probability of an Earth impact by a space rock, called a meteor when it enters the atmosphere, of that size range is fairly low, scaling according to the asteroid’s size: a 5-metre rock is estimated to target Earth once a year, and a 50-metre rock once every thousand years, according to NASA.

But with current capabilities, astronomers can’t see when such a rock targets Earth until days prior.

“We don’t know where most of the asteroids are that can cause local to regional devastation,” said Terik Daly, a planetary scientist at the Johns Hopkins Applied Physics Laboratory.

The roughly 20-metre meteor that exploded in 2013 over Chelyabinsk, Russia, is a once-every-100-years event, according to NASA’s Jet Propulsion Laboratory. It created a shockwave that shattered tens of thousands of windows and caused US$33-million in damage, and no one saw it coming before it entered Earth’s atmosphere.

Some astronomers consider relying only on statistical probabilities and estimates of asteroid populations an unnecessary risk, when improvements could be made to NASA’s ability to detect them.

“How many natural hazards are there that we could actually do something about and prevent for a billion dollars? There’s not many,” said Mr. Daly, whose work focuses on defending Earth from hazardous asteroids.

One major upgrade to NASA’s detection arsenal will be NEO Surveyor, a US$1.2-billion telescope under development that will launch nearly a million miles from Earth and surveil a wide field of asteroids. It promises a significant advantage over today’s ground-based telescopes that are hindered by daytime light and Earth’s atmosphere.

That new telescope will help NASA meet a goal assigned by U.S. Congress in 2005: detect 90 per cent of the total expected number of asteroids bigger than 140 metres, or those big enough to destroy anything from a region to an entire continent.

“With Surveyor, we’re really focusing on finding the one asteroid that could cause a really bad day for a lot of people,” said Amy Mainzer, NEO Surveyor principal investigator. “But we’re also tasked with getting good statistics on the smaller objects, down to about the size of the Chelyabinsk object.”

NASA has fallen years behind on its congressional goal, which was ordered for completion by 2020. The agency proposed last year to cut the telescope’s 2023 budget by three-quarters and a two-year launch delay to 2028 “to support higher-priority missions” elsewhere in NASA’s science portfolio.

Asteroid detection gained greater importance last year after NASA slammed a refrigerator-sized spacecraft into an asteroid to test its ability to knock a potentially hazardous space rock off a collision course with Earth.

The successful demonstration, called the Double Asteroid Redirection Test (DART), affirmed for the first time a method of planetary defense.

“NEO Surveyor is of the utmost importance, especially now that we know from DART that we really can do something about it,” Mr. Daly said.

“So by golly, we gotta find these asteroids.”

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‘Green Comet’ Begins Closest Approach To Earth As A ‘Snow Moon’ Shines Near Mars: The Night Sky This Week – Forbes

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Each Monday I pick out the northern hemisphere’s celestial highlights (mid-northern latitudes) for the week ahead, but be sure to check my main feed for more in-depth articles on stargazing, astronomy, eclipses and more.

What To See In The Night Sky This Week: January 30-February 5, 2023

With the possibility of Comet C/2022 E3 (ZTF) becoming a naked-eye object and a full moon occulting the red planet Mars it’s arguably one of the most interesting weeks of 2023 so far, sky-wise. The sight of a comet and a planetary disappearance (though only for some) is also joined by the second full moon of winter and the planet Mercury becoming visible in the predawn sky.

However, don’t forget to observe Venus, which is now shining very brightly in the western sky right after sunset. Venus observing aside, get ready for some early mornings and late evenings, stargazers!

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Monday, January 30, 2023: Moon near Mars

Look high in the southwestern sky tonight and you’ll see a 72%-lit waxing gibbous moon alongside reddish Mars. Slightly to its side will be the sparkling open cluster of stars called the Pleiades or “Seven Sisters.” However, if you live in some southern US states or central America then you will also see the weird sight of the moon occulting the red planet, though only its disappearance—it will reappear only for those in the Pacific region.

Tuesday, January 31, 2023: Mercury in the morning

Today sees Mercury at its Greatest Western Elongation, the point when the innermost planet in the solar system reaches its farthest from the sun from our point of view. Use binoculars to find it in low in the southeastern sky just before sunrise. It will actually be visible slightly higher in the sky on Wednesday and Thursday.

Wednesday, February 1, 2023: A comet at its brightest?

In theory, tonight should see comet C/2022 E3 (ZTF) at its brightest simply because it will be closest to Earth. It should be visible through binoculars and small telescopes and, just maybe, with the naked eye—though likely only under very dark skies.

Sunday, February 5, 2023: Snow Moon

At 18:29 UTC today our natural satellite in space reaches its full phase. It will be best viewed at moonrise where you are tonight when it will appear on the eastern horizon in a blaze of orange.

Once it’s risen and darkness creeps up have a look close at Capella, the brightest star in the constellation Auriga, for comet C/2022 E3 (ZTF).

Constellation of the week: Cassiopeia

This constellation is located near the North Star and is visible throughout the year in the northern hemisphere. It is represented by a “W” shaped pattern of stars and is easily identifiable by its distinctive shape. Cassiopeia is named after the queen of Ethiopia in Greek mythology and is located in the direction opposite the Big Dipper, which is part of the constellation Ursa Major.

Object of the week: M52

An open cluster of stars in the northern part of the constellation of mCassipoei, M52 is about 5,000 light-years from Earth. It’s visible to the naked eye under dark-sky conditions as a small, diffuse patch of light, though it’s best observed through binoculars.

Times and dates given apply to mid-northern latitudes. For the most accurate location-specific information consult online planetariums like Stellarium and The Sky Live. Check planet-rise/planet-set, sunrise/sunset and moonrise/moonset times for where you are.

Wishing you clear skies and wide eyes.

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Regular old rock? Think again. Here’s your guide to erratic boulders in Alberta

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If you’re taking a walk just east of Calgary’s Coventry Hills neighbourhood, you may dismiss it as a regular old rock covered in graffiti.

But to Lincoln Friske, it’s a local treasure.

A large erratic boulder sits just past Nose Creek Park. Friske visits the massive rock on his daily dog walks, and he decided recently to create a digital 3D model of it so others could appreciate it, too.

“It’s set up just like an anomaly in the middle of this massive park,” he said in an interview on the Calgary Eyeopener. “Most people didn’t even know there was this graffiti erratic in our own backyard.”

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Erratics are stones, boulders or big blocks picked up and moved by glaciers from one place to another during the last ice age.

There are thousands dotting the Foothills, part of a 600-kilometre section known as the Foothills Erratics Train. It runs from about Hinton, Alta., all the way down to the Montana border.

Eva Enkelmann, an associate professor in the University of Calgary’s department of geoscience, says the boulders typically look out of place.

“It almost looks like it fell out of the sky. What that means is it doesn’t really match with the rocks you find in that area,” she said.

The stones are typically white, grey or slightly pink.

They’re made of quartzite — or cemented sand grains — dating back some 500 million years, according to Dale Leckie, geologist and author of The Scenic Geology of Alberta: A Roadside Touring And Hiking Guide.

This large boulder sits in Nose Hill Park, part of the Foothills Erratics Train. (Submitted by Dale Leckie)

Researchers have traced the material back to Mount Edith Cavell in Jasper National Park, about 300 kilometres northwest of Calgary.

“They are a very distinctive type of rock,” Leckie said.

“You can see features inside them, which geologists call cross-beds. They’re structures from the waves and the tides when they were deposited.”

So how did they get here?

About 20,000 years ago, a landslide occurred in Jasper National Park.

The tumbling boulders fell onto valley glaciers in the Athabasca River valley. They floated north, then east, then bumped into the Laurentide ice sheet, which covered most of Canada at the time, and were redirected southward, Leckie said.

Over time, they became scattered across the Foothills.

“When the ice melted, eventually it just let them down, I’ll say almost gently, onto the landscape, slipping, sliding back and forth,” Leckie said.

A map illustrates where the Foothills Erratics Train runs along the Rockies.
The Foothills Erratics Train runs from about Hinton, Alta., all the way down to the Montana border. (Government of Alberta)

Most of the erratic boulders landed in their current resting spots about 16,000 years ago.

Another distinctive feature is how solid the erratics are, Enkelmann said.

“Only rocks that are very, very hard actually survive such a long transport,” she said. “The river would usually round the boulders and eventually they turn into pebbles.”

If you look closely, though, some of the boulders do have some round edges along their lower portions.

That’s because hundreds of years ago, bison used to rub up on the boulders to get rid of their winter coats, Leckie said, creating more polished bits. They also created depressions around the boulders known as buffalo wallows.

Where are they?

You can stumble upon an erratic boulder in many farmers’ fields running along the Rocky Mountains, Leckie said, but some of the rocks have become famous landmarks.

The largest and most well-known example would be the Okotoks erratic — also known as Big Rock — which is about the size of a three-storey apartment building. A 3D model of the erratic is also available courtesy of the University of Calgary.

Blue signs describing the history of the rock sit on sidewalks, with the massive Okotoks erratic in the distance.
The Okotoks erratic is protected by the Government of Alberta for its geological and cultural importance. (Submitted by Dale Leckie)

The province designated Big Rock a provincial historic resource in 1978 to protect its geological and cultural importance.

“I think they’re so interesting because they’re just giant blocks,” Leckie said.

“They really grab your attention … they just jump out in the landscape because they’re standing high almost like sentinels.”

Several notable erratics are located in Calgary, including the one documented near Coventry Hills.

One sits on top of Nose Hill Park. Another, known as Split Rock, is in the city’s northeast, just off Harvest Hills Boulevard and Beddington Trail N.W.

A large rock split in half sits in a park.
Split rock can be found in Confluence Park in Calgary’s Beddington Heights neighbourhood. (Submitted by Dale Leckie)

Leckie has seen others in a McKenzie Lake playground and a Tuscany rest area. In Panorama Hills, there’s an erratic — sometimes referred to as crater rock — in a small park.

There are hundreds more, says Enkelmann, and once you’re aware of them, you’ll start to notice them everywhere.

“For me, it’s fascinating that you can weave this whole story by looking at these erratics here in the city, where we are relatively far away from the mountains but we have this evidence,” she said.

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