Tag Archives: Relic

Science

4 billion-year-old relic from early solar system heading our way

Leave a comment

This sequence shows how the nucleus of Comet C/2014 UN271 (Bernardinelli-Bernstein) was isolated from a vast shell of dust and gas surrounding the solid icy nucleus. On the left is a photo of the comet taken by the NASA Hubble Space Telescope’s Wide Field Camera 3 on January 8, 2022. A model of the coma (middle panel) was obtained by means of fitting the surface brightness profile assembled from the observed image on the left. This allowed for the coma to be subtracted, unveiling the point-like glow from the nucleus. Combined with radio telescope data, astronomers arrived at a precise measurement of the nucleus size. That’s no small feat from something about 2 billion miles away. Though the nucleus is estimated to be as large as 85 miles across, it is so far away it cannot be resolved by Hubble. Its size is derived from its reflectivity as measured by Hubble. The nucleus is estimated to be as black as charcoal. The nucleus area is gleaned from radio observations. Credit: NASA, ESA, Man-To Hui (Macau University of Science and Technology), David Jewitt (UCLA)Image Processing: Alyssa Pagan (STScI)

An enormous comet—approximately 80 miles across, more than twice the width of Rhode Island—is heading our way at 22,000 miles per hour from the edge of the solar system. Fortunately, it will never get closer than 1 billion miles from the sun, which is slightly farther from Earth than Saturn; that will be in 2031.

Comets, among the oldest objects in the solar system, are icy bodies that were unceremoniously tossed out of the solar system in a gravitational pinball game among the massive outer planets, said David Jewitt. The UCLA professor of planetary science and astronomy co-authored a new study of the comet in the Astrophysical Journal Letters. The evicted comets took up residence in the Oort cloud, a vast reservoir of far-flung comets encircling the solar system out to many billions of miles into deep space, he said.

A typical comet’s spectacular multimillion-mile-long tail, which makes it look like a skyrocket, belies the fact that the source at the heart of the fireworks is a solid nucleus of ice mixed with dust—essentially a dirty snowball. This huge one, called Comet C/2014 UN271 and discovered by astronomers Pedro Bernardinelli and Gary Bernstein, could be as large as 85 miles across.

“This comet is literally the tip of the iceberg for many thousands of comets that are too faint to see in the more distant parts of the solar system,” Jewitt said. “We’ve always suspected this comet had to be big because it is so bright at such a large distance. Now we confirm it is.”

This comet has the largest nucleus ever seen in a comet by astronomers. Jewitt and his colleagues determined the size of its nucleus using NASA’s Hubble Space Telescope. Its nucleus is about 50 times larger than those of most known comets. Its mass is estimated to be 500 trillion tons, a hundred thousand times greater than the mass of a typical comet found much closer to the sun.

“This is an amazing object, given how active it is when it’s still so far from the sun,” said lead author Man-To Hui, who earned his doctorate from UCLA in 2019 and is now with the Macau University of Science and Technology in Taipa, Macau. “We guessed the comet might be pretty big, but we needed the best data to confirm this.”

So the researchers used Hubble to take five photos of the comet on Jan. 8, 2022, and incorporated radio observations of the comet into their analysis.

Diagram comparing the size of the icy, solid nucleus of comet C/2014 UN271 (Bernardinelli-Bernstein) to several other comets. Credit: NASA, ESA, Zena Levy (STScI)

The comet is now less than 2 billion miles from the sun and in a few million years will loop back to its nesting ground in the Oort cloud, Jewitt said.

Comet C/2014 UN271 was first serendipitously observed in 2010, when it was 3 billion miles from the sun. Since then, it has been intensively studied by ground and space-based telescopes.

The challenge in measuring this comet was how to determine the solid nucleus from the huge dusty coma—the cloud of dust and gas—enveloping it. The comet is currently too far away for its nucleus to be visually resolved by Hubble. Instead, the Hubble data show a bright spike of light at the nucleus’ location. Hui and his colleagues next made a computer model of the surrounding coma and adjusted it to fit the Hubble images. Then, they subtracted the glow of the coma, leaving behind the nucleus.

Hui and his team compared the brightness of the nucleus to earlier radio observations from the Atacama Large Millimeter/submillimeter Array, or ALMA, in Chile. The new Hubble measurements are close to the earlier size estimates from ALMA, but convincingly suggest a darker nucleus surface than previously thought.

“It’s big and it’s blacker than coal,” Jewitt said.

The comet has been falling toward the sun for well over 1 million years. The Oort cloud is thought to be the nesting ground for trillions of comets. Jewitt thinks the Oort cloud extends from a few hundred times the distance between the sun and the Earth to at least a quarter of the way out to the distance of the nearest stars to our sun, in the Alpha Centauri system.

The Oort cloud’s comets were tossed out of the solar system billions of years ago by the gravitation of the massive outer planets, according to Jewitt. The far-flung comets travel back toward the sun and planets only if their orbits are disturbed by the gravitational tug of a passing star, the professor said.

First hypothesized in 1950 by Dutch astronomer Jan Oort, the Oort cloud still remains a theory because the comets that make it up are too faint and distant to be directly observed. This means the solar system’s largest structure is all but invisible, Jewitt said.

Comet 2014 UN271 the largest ever observed

More information:
Man-To Hui et al, Hubble Space Telescope Detection of the Nucleus of Comet C/2014 UN271 (Bernardinelli–Bernstein), The Astrophysical Journal Letters (2022). DOI: 10.3847/2041-8213/ac626a
Provided by
University of California, Los Angeles

Citation:
4 billion-year-old relic from early solar system heading our way (2022, April 12)
retrieved 12 April 2022
from https://phys.org/news/2022-04-billion-year-old-relic-early-solar.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.



Read original article here

Science

Dark matter could be a cosmic relic from extra dimensions

Leave a comment

Dark matter, the elusive substance that accounts for the majority of the mass in the universe, may be made up of massive particles called gravitons that first popped into existence in the first moment after the Big Bang. And these hypothetical particles might be cosmic refugees from extra dimensions, a new theory suggests. 

The researchers’ calculations hint that these particles could have been created in just the right quantities to explain dark matter, which can only be “seen” through its gravitational pull on ordinary matter. “Massive gravitons are produced by collisions of ordinary particles in the early universe. This process was believed to be too rare for the massive gravitons to be dark matter candidates,” study co-author Giacomo Cacciapaglia, a physicist at the University of Lyon in France, told Live Science.

But in a new study published in February in the journal Physical Review Letters (opens in new tab), Cacciapaglia, along with Korea University physicists Haiying Cai and Seung J. Lee, found that enough of these gravitons would have been made in the early universe to account for all of the dark matter we currently detect in the universe.

The gravitons, if they exist, would have a mass of less than 1 megaelectronvolt (MeV), so no more than twice the mass of an electron, the study found. This mass level is well below the scale at which the Higgs boson generates mass for ordinary matter — which is key for the model to produce enough of them to account for all the dark matter in the universe. (For comparison, the lightest known particle, the neutrino, weighs less than 2 electronvolts, while a proton weighs roughly 940 MeV, according to the National Institute of Standards and Technology (opens in new tab).)

The team found these hypothetical gravitons while hunting for evidence of extra dimensions, which some physicists suspect exist alongside the observed three dimensions of space and the fourth dimension, time.

Could the universe have more dimensions than we realize? (Image credit: Getty Images)

In the team’s theory, when gravity propagates through extra dimensions, it materializes in our universe as massive gravitons. 

But these particles would interact only weakly with ordinary matter, and only via the force of gravity. This description is eerily similar to what we know about dark matter, which does not interact with light yet has a gravitational influence felt everywhere in the universe. This gravitational influence, for instance, is what prevents galaxies from flying apart.

“The main advantage of massive gravitons as dark matter particles is that they only interact gravitationally, hence they can escape attempts to detect their presence,” Cacciapaglia said.

In contrast, other proposed dark matter candidates — such as weakly interacting massive particles, axions and neutrinos — might also be felt by their very subtle interactions with other forces and fields.

The fact that massive gravitons barely interact via gravity with the other particles and forces in the universe offers another advantage.

“Due to their very weak interactions, they decay so slowly that they remain stable over the lifetime of the universe,” Cacciapaglia said, “For the same reason, they are slowly produced during the expansion of the universe and accumulate there until today.”

In the past, physicists thought gravitons were unlikely dark matter candidates because the processes that create them are extremely rare. As a result, gravitons would be created at much lower rates than other particles.

The earliest stars and galaxies were formed in the first few hundred million years after the Big Bang, shown here in this illustration of the evolution of the universe. (Image credit: Harikane et al., NASA, EST and P. Oesch/Yale)

But the team found that in the picosecond (trillionth of a second) after the Big Bang, more of these gravitons would have been created than past theories suggested. This enhancement was enough for massive gravitons to completely explain the amount of dark matter we detect in the universe, the study found. 

“The enhancement did come as a shock,” Cacciapaglia said. “We had to perform many checks to make sure that the result was correct, as it results in a paradigm shift in the way we consider massive gravitons as potential dark matter candidates.”

Because massive gravitons form below the energy scale of the Higgs boson, they are freed from uncertainties related to higher energy scales, which current particle physics doesn’t describe very well.

The team’s theory connects physics studied at particle accelerators such as the Large Hadron Collider with the physics of gravity. This means that powerful particle accelerators like the Future Circular Collider at CERN, which should begin operating in 2035, could hunt for evidence of these potential dark matter particles.

“Probably the best shot we have is at future high-precision particle colliders,” Cacciapaglia said. “This is something we are currently investigating.” 

Originally published on Live Science.

Read original article here

Science

These Record-Breaking Simulations of The Universe Aim to Solve a ‘Tiny’ Problem

Leave a comment

What’s the mass of a neutrino? This problem has vexed physicists for decades. It’s tiny, no doubt, but by virtue of one of the particle’s most fundamental features, it can’t be zero. This still leaves plenty of room for guesswork. 

 

Like most riddles, the solution might be found by thinking outside of the box.

Physicists from the University of Tsukuba, Kyoto University, and the University of Tokyo in Japan have taken this advice to heart, using a revolutionary new method for modeling a significant chunk of the Universe to act as a testing ground for the subtle influence of neutrinos on the evolution of the cosmos.

It’s an idea that’s been tested before. But by applying a simulation used in other areas of physics, the researchers behind this new model think they can iron out some of the previous method’s shortcomings.

Neutrinos have been a theoretical part of the standard model of physics since 1930, and a confirmed member since their experimental discovery in the mid-1950s.

Technically, this ghost-like particle should be as massless as a photon. But a little over twenty years ago scientists worked out that not only do they come in a variety of forms, or ‘flavors’, they oscillate between them as they move.

For this very reason, physicists are confident neutrinos must have some kind of mass. Even if it’s a whisker off nothing. If neutrinos didn’t have mass, they would move at the speed of light in a vacuum, and if that was the case, time would stand still for them, so they wouldn’t be changing at all.

 

Searches for a precise mass using laboratory methods have put upper limits on how chunky a neutrino could potentially get, capping it at 1/500,000 of a single electron. So, it’s safe to say that somewhere between zip and 1/500,000th of an electron’s mass, we have our answer.

This new method might just bring us a little closer to that number, though admittedly, reconstructing most of a Universe to weigh something that barely exists isn’t without its irony.

Fortunately, what the humble neutrino lacks in punch it makes up for in sheer numbers.

From the very earliest moments in time, neutrinos have been a part of the Universe in significant amounts, churned out of the roiling vacuum itself within the first second of the Big Bang.

Just like the static hum of leftover radiation we still see as a cosmic microwave background, a neutrally-charged background of these neutrino relics surround us to this day.

There’s little doubt that masses of relic neutrinos would have had some kind of influence on the emerging structures of the Universe. Precisely what kind of effect isn’t so easy to figure out.

 

In a typical physics model of something like a solar system, or even a bunch of atoms, you might select a number of objects, define their behaviors with respect to one another, map them in 3D space, and let a computer calculate what happens over time.

Want more objects? Get a faster computer and add them in.

Such ‘N-body’ simulations can work well for large-scale simulations. But they have their limits, especially when rubbed up against physics of a more quantum nature.

Quantum objects like massive neutrinos don’t play by the same rules as classical particles. Neutrinos are only known to interact with gravity and weak subatomic forces, so it’s hard to say how different types of neutrinos stirred up the early Universe.

In this new model, the researchers borrowed an equation from plasma physics called a Vlasov simulation. Rather than treat relic neutrinos as discrete classical objects, the plasma-based equations allowed the team to describe them as if they were a continuous medium.

Running the simulation on a supercomputer at RIKEN Center for Computational Sciences in Japan demonstrated that the program could be used on a range of scales, resulting in fairly accurate representations of the structure of most of the observable Universe.

 

“Our largest simulation self-consistently combines the Vlasov simulation on 400 trillion grids with 330 billion-body calculations, and it accurately reproduces the complex dynamics of cosmic neutrinos,” says lead author of the study, physicist Koji Yoshikawa from the University of Tokyo.

Future work will be needed to tweak the details to hopefully zoom in on a more precise figure for the relic neutrino’s mass. Yet it’s an innovation that has already earned the team recognition in the form of a finalist’s place in the 2021 ACM Gordon Bell Prize.

Their revolutionary new way of modeling large-scale structures this way isn’t just a potential win for physicists eager to learn precisely how much mass a neutrino commands, either; it could have applications in plasma physics as well.

This research was published in SC ’21: Proceedings of the International Conference for High Performance Computing, Networking, Storage and Analysis.

 

Read original article here

Science

USU geologist examines ‘stunning’ Cold War relic with ominous implications

Leave a comment

LOGAN — A relic of the Cold War dug up during a secret military operation a half-century ago under the Greenland ice sheet provided what scientists called “stunning” and potentially ominous insights into the future of a warming Earth.

An international team of scientists announced their conclusions after studying a sample of ice and sediments that was captured in a drilling operation in the 1960s and then lost and forgotten. It wasn’t until 2017 that scientists rediscovered the sample in a freezer. They have now correlated that evidence with ice cores from other parts of Greenland to reach worrisome conclusions.

Utah State University geologist professor Tammy Rittenour, who played a significant role in the studies, called the findings “shocking” because they suggest that the entire Greenland ice sheet suffered a total meltdown at least twice and is much less stable than scientists previously thought.

If it melts again, Rittenour believes the consequences could be catastrophic for humans around the globe.

Apart from its scientific value, the saga of the frozen evidence also has jaw-dropping elements that could have come from a cold war thriller.

“It’s a cool story in a cold place,” Rittenour said, describing a top-secret 1960’s military operation that took place literally inside the ice.

Camp Century: A hidden base with a secret purpose

The Greenland ice sheet is an astonishing natural phenomenon, a gigantic slab of ice up to 1 mile deep that covers an area more than four times the size of California.

During the Cold War, Pentagon planners decided it was a perfect place to burrow inside and create a military base known as Camp Century. Tunnels and large workspaces were carved from the ice and covered over with snow and ice.

“You could dig out a huge bunker underneath the ice sheet and no one would know,” Rittenour said in an interview on the USU campus. “It would be invisible from above.”

The base itself was not a secret; CBS anchorman Walter Cronkite even went into the ice sheet and toured Camp Century in 1960. Military officials portrayed it as a site for scientific research. Its true purpose was a highly classified military secret.

Camp Century hid Project Iceworm which was supposed to be a secret military storage facility for 600 nuclear missiles. The Pentagon later abandoned the project. (Photo: University of Verrmont)

Known as Project Iceworm, the top-secret plan was to hide 600 mobile nuclear missiles under the ice and keep them ready for launch if the cold war with the Soviet Union suddenly turned into a hot war. Eventually, though, the Pentagon abandoned the plan.

“They had to,” Rittenour said, “because it was cut into ice and the ceiling kept collapsing.”

Camp Century left behind a unique piece of evidence for future scientists. In 1966 a huge drill rig inside the base cored all the way through the ice sheet, straight down nearly a mile, and even a few feet deeper, into sediments below.

“They collected that, looked at it, and put it in a freezer and forgot about it,” Rittenour said.

Project Iceworm: Clues for future scientists

In 2017, scientists rediscovered the forgotten sand and ice in a freezer in Denmark. They were astounded to find fossilized plants at the bottom of the ice-core. Rittenour calls it a “treasure trove” of evidence because it shows that the ice sheet must have melted away completely, two different times. Rittenour’s role was to determine how long ago that happened.

In her darkened “Luminescence Lab” on the USU Innovation Campus, she bombarded the sand with lasers to measure its luminescent properties.

“And that tells us how old it is,” she explained. “When it was last exposed to light.”

Rittenour said scientists previously thought the ice sheet had been stable for perhaps two-and-a-half million years. She said she was “shocked” to discover the sand was last exposed to sunlight less than 1 million years ago — possibly much less.

“Maybe only a half-million or several hundred thousand years ago that the ice-sheet melted away,” Rittenour said.

She said it implies that the ice sheet might be somewhat less stable than scientists had supposed and could be subject to meltdown over a relatively short span of time.

Meltdown: ‘An urgent problem for the next 50 years’

The findings have implications for the human race that could be catastrophic. Using various clues, including air-bubbles from glacial ice around the world, scientists have charted the rise and fall of atmospheric carbon dioxide over the last million years. When CO2 declined, the ice sheet grew. As CO2 increased, glacial ice began melting away. In the modern industrial era, atmospheric data shows a dramatic spike, an apparently unprecedented increase in carbon dioxide.

“Today (it’s) well outside the natural range of CO2 concentrations,” Rittenour said.

In recent years, the Greenland ice sheet seems to be melting at an accelerating pace. If a total meltdown happens again, oceans will rise an estimated 20 to 25 feet — a lot more if Antarctica melts down too. That threatens the lifestyle, and the lives, of hundreds of millions of people in coastal villages, towns and cities all over the world.

“If the Greenland ice sheet melted,” Rittenour said, “all of those coastal areas would be inundated, whole countries would be underwater and most of the world’s population would be disturbed.”

The half-century-old ice core doesn’t answer all the questions or predict the future. More studies are coming and this secret from the past, once buried under the ice, could tell us a lot about humanity’s future.

“This is not a twenty-generation problem,” said geoscientist Paul Bierman in the study team’s news release from the University of Vermont. “This is an urgent problem for the next 50 years.”

Photos

John Hollenhorst

More stories you may be interested in



Read original article here

Science

Somewhere Here Lies an Ancient Space Relic

Leave a comment


(Newser)
–
The search is on for an apricot-sized meteorite somewhere near Aiguillon, France. Cameras at an astronomy facility in Mauraux spotted the small space rock falling to Earth over southwest France last weekend, per the Guardian. The meteorite landed at 10:43pm Saturday near Aiguillon, some 60 miles southeast of Bordeaux, but no one has found it yet. And that’s not for lack of trying. Posters have been placed around the area asking for help in searching for the five-ounce rock and notifying residents of the precious commodity in their midst. “A fresh meteorite like this, which fell just a few days ago, hasn’t been altered by the Earth’s environment and therefore contains very precious information for scientists,” explains Mickael Wilmart, who belongs to the association that operates the observatory.

Meteorites, which usually have a shiny, burned exterior, are “relics of the solar system’s creation,” says Wilmart in a statement, per the Local. According to NASA, they “represent some of the original, diverse materials that formed planets billions of years ago.” Some even come from Mars. “We’re really counting on people to look in their gardens, or along the side of the road,” says Wilmart. “They might just stumble on this rock that’s wanted so badly.” The Mauraux facility is part of a network of 100 cameras assembled for the Sky Watch project, which seeks to track and identify the 10 or so meteorites thought to land in France each year, but success is no guarantee. Even knowing the rough location of the meteorite, “it’s a bit like searching for a needle in a haystack,” says Wilmart. (This guy found a meteorite in the worst possible way.)

var FBAPI = '119343999649';

window.fbAsyncInit = function() { FB.init({ appId: FBAPI, status: true, cookie: true, xfbml: true, oauth: true, authResponse: true, version: 'v2.5' });

FB.Event.subscribe('edge.create', function (response) { AnalyticsCustomEvent('Facebook', 'Like', 'P'); }); };

// Load the SDK asynchronously (function (d, s, id) { var js, fjs = d.getElementsByTagName(s)[0]; if (d.getElementById(id)) return; js = d.createElement(s); js.id = id; js.src = "https://connect.facebook.net/en_US/sdk.js"; fjs.parentNode.insertBefore(js, fjs); }(document, 'script', 'facebook-jssdk'));



Read original article here