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Science

Good News! The Solar System Is Going to Hold Together For Now

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If you’ve been laying in bed at night, fretting that the planets of the Solar System are going to go ricocheting off throughout the galaxy, you can set your mind at ease.

We have at least 100,000 years before that happens, according to new calculations.

 

In a new study, mathematicians Angel Zhivkov and Ivaylo Tounchev of the University of Sofia in Bulgaria lay out an analytical proof of the stability of the Solar System over the next 100 millennia, including all eight planets and Pluto.

Their calculations, yet to be peer-reviewed, show that the orbits of these bodies are not going to significantly vary over that time.

That may sound strange; after all, the Solar System has been here doing its thing for 4.5 billion years or so already. But it’s not, in fact, easy to model and predict what it’s going to continue doing in the future.

Studies, of course, have been conducted to try to calculate the future of the Solar System, using advanced computing to model the motions of the planets over millions or billions of years.

However, in order to cover such long timescales, they leave out some of the finer details. 

Although the work of Zhivkov and Tounchev covers a much shorter time period than other efforts, it increases the reliability of the results, they say.

This is because it accounts for deviations in the initial conditions, such as the orbital eccentricities and inclinations of the planets, as well as the masses of all the bodies in the system.

 

The ultimate fate of the Solar System is one that has perplexed scientists for a very long time. It was Isaac Newton who proposed that mutual interactions between the planets would eventually drive the Solar System into chaos. The long-time dynamical stability of our home planetary system has been grist for the brain-mill ever since.

That’s because the more bodies there are in a dynamical system, the harder it becomes to predict how they’re going to behave. Two bodies, locked in mutual orbit, are relatively simple to mathematically describe and predict.

The more bodies you add, however, the more complicated the mathematics becomes. That’s because the bodies start to perturb each other’s orbits, adding an element of chaos to the system. This is known as the N-body problem.

Solutions can be derived for specific individual cases, but there is no one formula that describes any and all N-body interactions. And the Solar System is very complex indeed, with not just eight planets and the Sun, but asteroids, dwarf planets and other bits and bobs drifting about.

 

We can probably mostly discount the really small things, like asteroids, but even so, that leaves a lot of bodies remaining in the system.

Zhivkov and Tounchev developed a numerical method that translates the orbital elements of the planets (and Pluto) into 54 first-order ordinary differential equations. The computer code, run on a desktop computer, then performed the calculations over 6,290,000 steps, with each step accounting for about six days.

The calculations suggest that “[t]he configuration of the osculating ellipses on which the planets move around the Sun will remain stable at least 100,000 years in the sense that the semi-major axis of each planet varies within or less than one percent”, the researchers write.

In other words, the Solar System isn’t going to mimic galactic billiards just yet.

Even when the initial conditions and masses were altered, the Solar System remained stable under the team’s calculations, and the researchers suggest stability might ultimately be maintained for a million or even a billion years, although a more powerful computer would be needed to make the calculations.  

Previous simulations found that it’s going to take around 100 billion years for the Solar System to break apart and scatter across the Milky Way.

By that time, the Sun will be well and truly dead, living its afterlife as a white dwarf, so humanity is unlikely to be around to see it, unless we’ve managed to find safe harbor somewhere else, far away. The likelihood of that, however, is questionable.

Anyway. Existential dread aside, you can read the team’s paper on preprint server arXiv.

 

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Science

Astronomers Discover a Bizarre Spiral Object Swirling Around The Milky Way’s Center

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As if cracking open a cosmic Russian nesting doll, astronomers have peered into the center of the Milky Way and discovered what appears to be a miniature spiral galaxy, swirling daintily around a single large star.

 

The star – located about 26,000 light-years from Earth near the dense and dusty galactic center – is about 32 times as massive as the sun and sits within an enormous disk of swirling gas, known as a “protostellar disk”. (The disk itself measures about 4,000 astronomical units wide – or 4,000 times the distance between Earth and the Sun).

Such disks are widespread in the universe, serving as stellar fuel that help young stars grow into big, bright suns over millions of years.

But astronomers have never seen one like this before: a galaxy in miniature, orbiting perilously close to the center of our own galaxy.

How did this mini-spiral come to be, and are there more like it out there?

The answers may lie in a mysterious object, about three times as massive as Earth’s sun, lurking just outside the spiral disk’s orbit, according to a new study published May 30 in the journal Nature Astronomy.

Using high-definition observations taken with the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile, the researchers found that the disk doesn’t appear to be moving in a way that would give it a natural spiral shape.

(SHAO)

Above: A schematic view of the history of the accretion disk and the intruding object. The three plots starting from the bottom left are snapshots from a numerical simulation, showing the system at the time of the flyby event, 4,000 years later, and 8,000 years after the event. The top right image was captured from ALMA observations, showing the disk with spirals and two objects around it, corresponding to the system 12,000 years after the event.

Rather, they wrote, the disk seems to have been literally stirred up by a near-collision with another body – possibly the mysterious triple-sun-sized object that’s still visible nearby it. 

 

To check this hypothesis, the team calculated a dozen potential orbits for the mysterious object, then ran a simulation to see if any of those orbits could have brought the object close enough to the protostellar disk to whip it into a spiral.

They found that, if the object followed one specific path, it could have skimmed past the disk about 12,000 years ago, perturbing the dust just enough to result in the vivid spiral shape seen today.

“The nice match among analytical calculations, the numerical simulation, and the ALMA observations provide robust evidence that the spiral arms in the disk are relics of the flyby of the intruding object,” study co-author Lu Xing, an associate researcher from the Shanghai Astronomical Observatory of the Chinese Academy of Sciences, said in a statement.

Besides offering the first direct images of a protostellar disk in the galactic center, this study shows that external objects can whip stellar disks into spiral shapes typically only seen on the galactic scale. 

And because the center of the Milky Way is millions of times denser with stars than our neck of the galaxy, it’s likely that near-miss events like this occur in the galactic center pretty regularly, the researchers said.

That means our galaxy’s center may be overloaded with miniature spirals, only waiting to be discovered. Scientists may not reach the center of this cosmic nesting doll for a long, long time.

Related Stories:

The 15 weirdest galaxies in our universe

The 12 strangest objects in the universe

9 ideas about black holes that will blow your mind

This article was originally published by Live Science. Read the original article here.

 

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Science

At 1.4 Million Mph, Astronomers Detected One of The Fastest Cosmic Objects of Its Kind

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When massive stars die, they don’t do so quietly.

Their deaths are spectacularly brilliant affairs that light up the cosmos, a supernova explosion that sends star guts punching out into space in a cloud of splendor. Meanwhile, the core of the star-that-was can linger on, collapsed into an ultra-dense neutron star or black hole.

 

If that explosion takes place in a certain way, it can send the collapsed core barreling across the Milky Way like a bat out of hell, at such insane velocities they can eventually punch clean out of the galaxy altogether, on a wild journey into intergalactic space.

It’s one of these objects that has been newly measured via data from the Chandra X-ray observatory: a type of pulsing neutron star known as a pulsar, ripping through its own entrails at a speed of around 612 kilometers per second (or 1.4 million miles per hour).

It’s one of the fastest objects of this kind ever detected. (The fastest known star in the Milky Way is not a supernova remnant that has been kicked by an explosion, but a star orbiting Sgr A*, the supermassive black hole in the galactic center. At the fastest point in its orbit, it moves at a wild 24,000 kilometers per second.)

“We directly saw motion of the pulsar in X-rays, something we could only do with Chandra’s very sharp vision,” said astrophysicist Xi Long of the Harvard & Smithsonian Center for Astrophysics (CfA).

 

“Because it is so distant, we had to measure the equivalent of the width of a quarter about 15 miles away to see this motion.”

The detection was made by looking at a glowing supernova remnant some 20,000 light-years away, named G292.0+1.8. Previous observations had revealed a speeding pulsar therein. Long and his colleagues wanted to study the object to see if it could reveal the history of the supernova, by tracing its motion to the center of the object in reverse.

“We only have a handful of supernova explosions that also have a reliable historical record tied to them,” said astrophysicist Daniel Patnaude of the CfA, “so we wanted to check if G292.0+1.8 could be added to this group.”

They studied images taken of the supernova remnant in 2006 and 2016, and used Gaia data on its current location in the Milky Way, comparing the differences in the pulsar’s position. These comparisons revealed something extremely interesting: The dead star appears to be moving 30 percent faster than previous estimates had suggested.

This means it has taken a much shorter time to travel from the center of the supernova remnant, suggesting the supernova itself took place much more recently. Previous estimates put the date of the supernova at around 3,000 years ago; the new estimates take it to around 2,000 years ago.

 

The revised velocity of the pulsar also allowed the team to conduct a new, detailed investigation into how the dead star might have been ejected from the center of the supernova. They came up with two scenarios, both involving a similar mechanism.

In the first, neutrinos are ejected from the supernova explosion asymmetrically. In the other, debris from the explosion is ejected asymmetrically. However, because the neutrino energy would need to be extremely large, the more likely explanation is asymmetrical debris.

Basically, a lopsided explosion can ‘kick’ the collapsed core of a dead star out into space at extremely high speeds; in this case, the star is currently traveling at a speed higher than the Milky Way mid-disk escape velocity of 550 kilometers per second, although it will take quite some time to get there, and it may slow down over time.

In fact, its true speed may be even higher than 612 kilometers per second, because it is traveling very slightly along our line of sight.

“This pulsar is about 200 million times more energetic than Earth’s motion around the Sun,” said astrophysicist Paul Plucinsky of CfA. “It appears to have received its powerful kick just because the supernova explosion was asymmetric.”

The team’s research, presented at the 240th meeting of the American Astronomical Society, has been accepted into The Astrophysical Journal and is available on arXiv.

 

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Technology

40K Game Developers Criticised Over Ridiculous Twitch Drops

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Screenshot: Complex Games

Complex Games, the developers of the new Warhammer 40,000: Chaos Gate – Daemonhunters, have issued a statement apologising to players after running a campaign where certain in-game items were only available to those who sat through some Twitch streams.

Via PC Gamer, while Complex probably thought they were running a fairly standard (by 2022 standards anyway) release window promotional stuff, the nature of the items and the fanbase/platform in question weren’t having it. Here’s an example of a negative review left on the game’s Steam page as a result, one of many that presumably prompted the statement:

The game would have gotten a thumbs up but for one thing. The developers for some ridiculous reason decided to put 11 ingame items(not skins or cosmetics but actual weapons and armor) behind twitch drops on the day of release. In order to get these items you not only have to create and link a Frontier account and a Twitch account but you have to watch hours and hours of inane twitch streamers prattling on instead of actually playing the game you paid for. They also are timed so if you miss them you miss them forever.

If there was another way to earn these ingame it would not be a big deal but I’m not gonna watch ♥♥♥♥♥♥♥ Angry Joe for 2 hours just to get a weapon.

The Angry Joe stream was actually only 45 minutes, but their point remains. The items weren’t anything fancy or game-breaking, most of them were just very slight variations on early-game weapons and armour that you’ll move past in a few hours anyway, but it’s the spirit of the move—and it’s mandates on player’s time if they want to try out everything the game has to offer—that has upset people as much as its practical consequences.

As a result, Complex have said that every item offered during the streams will now be given away to free to all players later this month.

Ave Imperator Force Commanders,

We are pleased to see so many of you enjoying Warhammer 40000 Chaos Gate: Daemonhunters. Whilst we are pleased to see you enjoying the gameplay, we are also listening to your feedback.

One of the areas we have noted is the frustrations around the various Twitch drop campaigns we ran around the launch of the game. Whilst the sole objective of these campaigns was to drive awareness, we understand many feel this locked in-game items away from them.

This was certainly not our intention and we appreciate you sharing your thoughts on this. As such, we will make all items from every Twitch drop campaign available to players via one of our planned updates in May. We will confirm which update and exact date when this is finalised.

We hope this addresses your frustrations and you can continue to smite the forces of Chaos with these items in your Armoury.

If you haven’t even heard of Warhammer 40,000: Chaos Gate – Daemonhunters, let alone played it, I’m going to assume it’s because it’s the worst name ever and that the thought of yet another Warhammer game has caused your eyeballs to roll back into your skull.

The thing is…this game is really good, and very XCOM, so for anyone who has glossed right over it but is now preparing to double back at this revelation, I’ll be sharing some impressions of it later in the week.



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Science

Scientists Uncover Largest Known Crater on Earth From The Last 100,000 Years

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A crescent-shaped crater in Northeast China holds the record as the largest impact crater on Earth that formed in the last 100,000 years.

Prior to 2020, the only other impact crater ever discovered in China was found in Xiuyan county of the coastal province of Liaoning, according to a statement from the NASA Earth Observatory.

 

Then, in July 2021, scientists confirmed that a geological structure in the Lesser Xing’an mountain range had formed as a result of a space rock striking Earth. The team published a description of the newfound impact crater that month in the journal Meteoritics and Planetary Science.

The Yilan crater measures about 1.15 miles (1.85 kilometers) across and likely formed about 46,000 to 53,000 years ago, based on radiocarbon dating of charcoal and organic lake sediments from the site, the NASA statement says.

Researchers collected these sediment samples by extracting a drill core from the center of the crater, Forbes reported.  

Related: Crash! 10 biggest impact craters on Earth 

Beneath more than 328 feet (100 meters) of layered lake and swamp sediments lay a nearly 1,000-foot-thick (320 m) slab of brecciated granite, which is granite made up of many rocky fragments cemented together in a matrix, the team found. This rock bears telltale scars of having been struck by a meteorite. 

For example, fragments of the rock show signs of having melted and recrystallized during the impact, as the granite rapidly heated and then cooled off. Other fragments of the rock escaped this melting process, and instead contain “shocked” quartz that shattered in a distinct pattern when the space rock crashed down, according to Forbes. 

 

The team also uncovered teardrop-shaped glass fragments and pieces of glass pierced with tiny holes made by gas bubbles; both of these features also indicate that a high-intensity impact took place there, according to the NASA statement.

A portion of the Yilan crater’s southern rim is missing, so the geological structure looks crescent-shaped from above, the Global Times reported. Such crescent-shaped impact craters are relatively rare on Earth, Chen Ming, one of the authors of the article and a research fellow from the Guangzhou Institute of Geochemistry, told the Global Times.

In October 2021, the Landsat-8 satellite captured a striking snapshot of the crater’s northern rim, and scientists are now investigating how and when the southern rim disappeared, according to the NASA statement.

The so-called Meteor Crater in Arizona previously held the record for largest impact crater less than 100,000 years old; it’s about 49,000 to 50,000 years old and measures 0.75 miles (1.2 km) in diameter. The Xiuyan crater, by comparison, measures 1.1 miles (1.8 km) across, but its age is unknown, Forbes reported.

Related content:

Space-y tales: The 5 strangest meteorites

When space attacks: The 6 craziest meteor impacts

Photos: Craters hidden beneath the Greenland ice sheet

This article was originally published by Live Science. Read the original article here.

 

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Science

Powerful Geomagnetic Storm Sends Dozens of SpaceX Satellites to a Fiery Doom

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A powerful geomagnetic storm has doomed 40 Starlink satellites launched by SpaceX last week, the company has announced.

Elon Musk’s company launched a Falcon 9 rocket bearing the 49 satellites from Kennedy Space Center in Florida on Thursday (Feb. 3), but a geomagnetic storm that struck a day later sent the satellites plummeting back toward Earth, where they will burn up in the atmosphere.

 

“Unfortunately, the satellites deployed on Thursday were significantly impacted by a geomagnetic storm on Friday,” SpaceX said in a statement.

“Preliminary analysis show[s] the increased drag at the low altitudes prevented the satellites from leaving safe mode to begin orbit-raising maneuvers, and up to 40 of the satellites will reenter or already have reentered the Earth’s atmosphere.”

Related: The 12 strangest objects in the Universe

Geomagnetic storms occur when a surge of solar wind – charged particles from the Sun – smashes into Earth’s magnetic field and generates charged particles and currents in Earth’s upper atmosphere.

The surge warms the upper atmosphere and increases its atmospheric density such that the drag experienced by satellites in low Earth orbit can be enough to send them tumbling back to Earth. The geomagnetic storm experienced by the satellites came from solar wind kicked out by a January 30 coronal mass ejection – an eruption of the Sun. 

After launch, the 49 SpaceX satellites began orbiting as close to 130 miles (210 kilometers) from Earth. This low orbit was intentionally designed to make the satellites easily disposable in the event of a post-launch failure, but the low orbit also left them vulnerable to the geomagnetic storm.

 

SpaceX said in the statement that the satellites’ GPS systems show the storm caused atmospheric drag to “increase up to 50 per cent higher than during previous launches.” In response, the satellites were commanded to “take cover from the storm” by flying “edge-on (like a sheet of paper)”.

This “edge-on” positioning, by decreasing the surface area of the satellite passing through the atmosphere, was an attempt to halt the rapid deceleration of the satellites.

But the drag was too much. Forty of the satellites are now set to plummet back to Earth. SpaceX assures the public that, because the company’s satellites are designed to disintegrate upon reentry, “no orbital debris is created and no satellite parts hit the ground”.

Since the first Starlink satellites were launched in 2019, SpaceX has put 2,000 of them into Earth orbit, and the company plans to place as many as 42,000 satellites into an Earth-orbiting mega-constellation.

The Starlink program would give customers high-speed internet service from anywhere in the world, but it has come under sustained criticism from astronomers because its shiny satellites often leave bright streaks in the night sky, ruining astronomical observations.

 

A 2021 study showed that the 9,300 tons (8,440 metric tons) of space objects currently orbiting Earth, including inoperative satellites and chunks of spent rocket stages, have increased the overall brightness of the night sky by more than 10 percent, rendering large parts of Earth light-polluted, Live Science previously reported.

Critics also say these SpaceX satellites clog up near-Earth orbital slots that could be used by other companies or countries.

Space experts have even warned that once the first 12,000 satellites of Starlink’s first-generation constellation are in orbit, they could become responsible for up to 90 percent of near misses between two spacecraft in low Earth orbit, Live Science sister site Space.com reported.

In December 2021, the director general of the European Space Agency, Josef Aschbacher, said Musk was “making the rules” in space, and he called for the European Union and other countries to coordinate so that SpaceX’s satellites did not prevent others from launching their own.

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15 unforgettable images of stars

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This article was originally published by Live Science. Read the original article here.

 

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Science

Breathtaking New Chandra Pics Show Cosmic Objects Like You’ve Never Seen Them Before

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Human vision may be limited to a specific range of wavelengths, but that doesn’t mean we’ll never understand the full complexity of light in our Universe.

Instruments can peer into the cosmos in regimes that are otherwise invisible to our eyes, showing us not just the dynamics of the stars, but their absolutely awe-inspiring beauty. This is what we see in a new collection of images from the Chandra X-ray Observatory that combines its data with other instruments for spectacular multi-wavelength views.

 

Because different wavelengths of light have different energies, these images can show us the dynamics of cosmic objects from low energy to high. This can help scientists unravel the mechanisms behind the glorious light-shows.

R Aquarii. (X-ray: NASA/CXC/SAO/R. Montez et al.; Optical: NASA/ESA/STScI)

R Aquarii, seen here in X-ray from Chandra (purple) and near-infrared and optical from the Hubble Space Telescope (red and blue) is a pair of stars locked in a violent dance of death 650 light-years from Earth. One of the stars is a red giant, known as a Mira variable star, at the very end of its lifespan. Stars of this kind have already lost at least half their material, and as they pulsate, they reach a brightness 1,000 times that of the Sun.

The other star is a white dwarf – a ‘dead’ star that has exhausted its nuclear fuel – and also has a lot going on. As the red giant ejects material, the white dwarf slurps it up. The material it devours from the red giant accumulates on its surface, occasionally triggering an enormous thermonuclear explosion that blasts the material out into space.

This violent interaction is creating clouds of dust and gas in a nebula around the binary, churned up by their gravitational interactions and explosive shock waves.

Cassiopeia A. (NASA/CXC/SAO; Optical: NASA/STScI; Radio: NSF/NRAO/VLA)

Cassiopeia A, located 11,000 light-years away, is one of the most famous and well-studied objects in the Milky Way. It’s what we call a supernova remnant – what’s left after a massive star has gone kaboom. Here, X-ray data from Chandra are combined with radio data from the Karl Jansky Very Large Array (dark purple, blue, and white) and optical data from Hubble (orange).

These different wavelengths can reveal what’s actually happening in the expanding cloud, consisting of the guts of a dead star. From these combined data, scientists are able to identify different elements within the explosion. The Chandra data alone revealed that the exploding star blasted off 10,000 Earth masses of sulfur; 20,000 Earth masses of silicon; 70,000 Earth masses of iron; and 1 million Earth masses of oxygen.

This is important information, because it tells us what elements were produced in the star when it died. In turn, scientists can use these data to learn more about the star when it was still burning, to make predictions about similar stars in our galaxy.

( NASA/CXC/SAO; Optical: NASA/STScI & Palomar Observatory 5-m Hale Telescope)

This image shows two different effects produced by a single dead star called PSR B2224+65. The pink streak is X-ray emission ejected from the poles of a type of neutron star called a pulsar. That’s the collapsed core of a dead massive star that emits pulsing radiation as it rotates.

That would be interesting enough, but PSR B2224+65 is also what we call a runaway star; it’s speeding through the galaxy after being punted into space at a speed of around 1,600 kilometers, or 1,000 miles, per second. That motion has created a wake in the interstellar medium; you can see it in the lower left of the image in optical wavelengths (blue). Because it looks uncannily like a guitar, astronomers have named it the Guitar Nebula.

Abell 2597. (NASA/CXC/SAO/G. Tremblay et al.; Optical: DSS; H-Alpha: LCO/IMACS/MMTF)

Some of the biggest collections of objects in the Universe are galaxy clusters. These clusters can contain thousands of galaxies, bound together by, and interacting via, gravity. This cluster is Abell 2597, roughly a billion light-years away, and multi-wavelength astronomy has helped scientists learn more about the behavior of the supermassive black hole in its central galaxy.

Just a few years ago, astronomers saw evidence that this behemoth is blasting out molecular gas as it gravitationally accretes material. This molecular gas is then falling into the black hole, and feeding the cycle anew. It’s a phenomenon known as a “fountain”. The hot outflow and cold infall were observed using two different instruments; then X-ray data from Chandra revealed that they’re part of the same process.

This image above shows the cluster in X-rays (blue) from Chandra, and optical from the Digitized Sky Survey (orange) and Las Campanas Observatory (red).

NGC 4490, the Cocoon Galaxy. (X-ray: NASA/CXC/SAO; Optical: NASA/STScI)

Finally, this image shows two galaxies that have merged. It’s called NGC 4490, or the Cocoon Galaxy, and, fascinatingly, multi-wavelength astronomy revealed a secret in its core. It has not one, but two supermassive black holes, one of which is only visible in optical data, and the other can only be seen in radio and infrared. Both had been seen separately, but it took years for astronomers to put the two together.

This double nucleus is the result of that merger process; each of the two galaxies had its own supermassive black hole. Eventually, the two black holes will also likely merge, resulting in one much bigger monster.

This image combines X-ray data from Chandra (purple) and optical data from Hubble (red, green and blue) to show the results of another close galactic encounter. NGC 4490 had a hit-and-run with a smaller galaxy, NGC 4485, which perturbed the gas and triggered waves of star formation, seen here in red.

You can download larger versions of these images on the Chandra website. Cover image credit: X-ray: NASA/CXC/SAO; Optical: NASA/STScI, Palomar Observatory, DSS; Radio: NSF/NRAO/VLA; H-Alpha: LCO/IMACS/MMTF

 

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Science

A New Study Calculates The Number of Black Holes in The Universe. It’s a Lot

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Because we can’t see black holes, it’s hard to know exactly how many are out there in the big, wide Universe.

But that doesn’t mean we have no means of trying to figure it out.

Stellar-mass black holes are the collapsed cores of dead massive stars, and new research incorporating how these stars and binaries form and evolve has been able to derive a new estimate of the stellar-mass black hole population of the Universe.

 

The number is pretty jaw-dropping: 40 quintillion, or 40,000,000,000,000,000,000 black holes, roughly making up 1 percent of all the normal matter in the observable Universe.

“The innovative character of this work is in the coupling of a detailed model of stellar and binary evolution with advanced recipes for star formation and metal enrichment in individual galaxies,” explains astrophysicist Alex Sicilia of the International School of Advanced Studies (SISSA) in Italy.

“This is one of the first, and one of the most robust, ab initio computation[s] of the stellar black hole mass function across cosmic history.”

Black holes are a huge question mark hanging over our understanding of the Universe – or rather, a lot of question marks. But if we have a good idea of how many black holes are out there, that could help answer some of those questions.

One approach is to estimate the history of massive stars in the Universe. We’d then be able to calculate the number of black holes that ought to be in any given volume of space.

This knowledge might yield clues as to the growth and evolution of supermassive black holes millions or billions of times the mass of the Sun, constituting the cores of galaxies.

 

Sicilia and his colleagues took a computational approach. They only included black holes that form via the evolution of single or binary stars, and taking into account the role of black hole mergers, whose numbers can be estimated based on gravitational wave data, and which produce black holes of slightly higher masses.

This allowed them to calculate the birthrate of stellar-mass black holes between five and 160 times the mass of the Sun over the lifespan of the Universe.

This birthrate suggests that there should be roughly 40 quintillion stellar-mass black holes scattered throughout the observable Universe today, with the most massive stellar-mass black holes produced by binary black hole mergers in clusters of stars.

The team compared their results against the gravitational wave data, and found that their estimate of the rate of black hole mergers was in good agreement with the observational data. This suggests that star cluster mergers are likely behind the black hole collisions we’ve seen.

By calculating the birthrate over time, the researchers were also able to derive an estimate for the number of stellar-mass black holes in the early Universe. This is of great interest, since observations of the distant Universe have revealed supermassive black holes at a shockingly early time after the Big Bang.

 

It’s unclear how these behemoths grew so large so quickly. Some current questions concern the mass of the black hole ‘seeds’ from which they grew – whether they were light stellar-mass black holes or ‘heavy’ intermediate-mass black holes.

The team’s research will provide a basis for investigating these questions. This paper was the first in a series; future papers will investigate intermediate-mass black holes and supermassive black holes for a more complete picture of the black hole distribution across the Universe.

“Our work provides a robust theory for the generation of light seeds for (super)massive black holes at high redshift, and can constitute a starting point to investigate the origin of ‘heavy seeds’, that we will pursue in a forthcoming paper,” says astrophysicist Lumen Boco of SISSA.

The team’s research has been published in The Astrophysical Journal.

 

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Science

A 100,000-Year-Old Mammoth Tusk Has Been Discovered Off The Coast of California

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To the untrained eye, it may have looked like a giant wood log. In reality, scientists had spotted something unusual off the California coast two years ago: a 3-foot (1-meter) long mammoth tusk.

 

A research team at the Monterey Bay Aquarium Research Institute discovered the tusk in 2019 while exploring an underwater mountain roughly 10,000 feet (3,000 meters) below the ocean’s surface.

Though other mammoth fossils had been plucked from the ocean before, it’s rare for such objects to nestle along the deep seafloor, Daniel Fisher, a paleontologist at the University of Michigan, said in a press release. 

Scientists ultimately determined that the tusk belonged to a young female Columbian mammoth, possibly one that lived during the Lower Paleolithic era, which spanned 2.7 million to 200,000 years ago. Researchers are still working to determine the creature’s precise age, along with more details about its life – including its diet and how often it reproduced.

“This is an ‘Indiana Jones’ mixed with ‘Jurassic Park’ moment,” Katie Moon, a postdoctoral researcher at the University of California, Santa Cruz, told The New York Times.

The discovery could ultimately signal the presence of other ancient animal fossils hidden in the deep sea.

Scientists prepare to clean the large tusk piece in the ship’s laboratory. (Darrin Schultz © 2021 MBARI)

Scientists broke a piece of the mammoth tusk two years ago

Monterey Bay scientists hadn’t intended to encounter a mammoth tusk in 2019. At the time, the research team was roving the ocean with remotely operated vehicles in search of deep-sea species.

“You start to ‘expect the unexpected’ when exploring the deep sea, but I’m still stunned that we came upon the ancient tusk of a mammoth,” Steven Haddock, senior scientist at the Monterey Bay Aquarium Research Institute, said in the press release.

 

On a hunch, the scientists decided to retrieve the tusk from the ocean floor, but the tip broke off and they weren’t able to collect the full specimen. The team later revisited the site in July to grab the rest of the artifact. This time, they attached soft materials like sponges to the remotely operated vehicle then gingerly lifted the tusk using the vehicle’s robotic arms.

The full tusk gave scientists a much larger sample of mammoth DNA, which they used to determine its species.

Scientists believe the Columbian mammoth was one of the largest creatures of its kind – likely the result of crossbreeding between a woolly mammoth and another mammoth species. It probably used its tusks to protect itself and forage for food when it roamed North America up to 10,000 years ago.

Paleontologist slices a section from the core of the smaller tusk fragment. (Darrin Schultz © 2021 MBARI)

The deep sea’s cool, high-pressure environment is ideal for preserving fossils

Scientists are now analyzing the tusk’s radioisotopes, or naturally decaying atoms, to pinpoint how long ago the mammoth lived. Since scientists know the rate at which isotopes like uranium and thorium decay, they can determine the tusk’s age based on how much of these isotopes are still present in the artifact.

So far, this technique suggests the mammoth tusk is much more than 100,000 years old.

 

Scientists believe the ocean is responsible for keeping the artifact in such pristine condition.

Deep-sea temperatures are just above freezing – around 4 degrees Celsius (39 degrees Fahrenheit), on average. This frigid climate slows down the rate of fossil decay, just like putting food in the freezer prevents it from spoiling too soon. 

Fossils also have a better chance of surviving in the deep sea’s high-pressure environment – the underwater pressure in the ocean’s deepest trenches is 1,100 times greater than it is at the water’s surface.

“If the tusk had been found on land, deciphering its history would not be as straightforward,” Terrence Blackburn, associate professor at the University of California, Santa Cruz, said in the press release.

This article was originally published by Business Insider.

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Science

A Chunk of Satellite Almost Hit The ISS, Requiring an ‘Urgent Change of Orbit’

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Earlier this week, the International Space Station (ISS) was forced to maneuver out of the way of a potential collision with space junk. With a crew of astronauts and cosmonauts on board, this required an urgent change of orbit on November 11.

 

Over the station’s 23-year orbital lifetime, there have been about 30 close encounters with orbital debris requiring evasive action. Three of these near-misses occurred in 2020.

In May this year there was a hit: a tiny piece of space junk punched a 5mm hole in the ISS’s Canadian-built robot arm.

This week’s incident involved a piece of debris from the defunct Fengyun-1C weather satellite, destroyed in 2007 by a Chinese anti-satellite missile test. The satellite exploded into more than 3,500 pieces of debris, most of which are still orbiting. Many have now fallen into the ISS’s orbital region.

To avoid the collision, a Russian Progress supply spacecraft docked to the station fired its rockets for just over six minutes. This changed the ISS’s speed by 0.7 meters per second and raised its orbit, already more than 400 km (250 miles) high, by about 1.2 km (0.7 miles).

Orbit is getting crowded

Space debris has become a major concern for all satellites orbiting the Earth, not just the football-field-sized ISS. As well as notable satellites such as the smaller Chinese Tiangong space station and the Hubble Space Telescope, there are thousands of others.

As the largest inhabited space station, the ISS is the most vulnerable target. It orbits at 7.66 kilometers (4.75 miles) a second, fast enough to travel from Perth to Brisbane in under eight minutes.

 

A collision at that speed with even a small piece of debris could produce serious damage. What counts is the relative speed of the satellite and the junk, so some collisions could be slower while others could be faster and do even more damage.

As low Earth orbit becomes increasingly crowded, there is more and more to run into. There are already almost 5,000 satellites currently operating, with many more on the way.

SpaceX alone will soon have more than 2,000 Starlink internet satellites in orbit, on its way to an initial goal of 12,000 and perhaps eventually 40,000.

A rising tide of junk

If it was only the satellites themselves in orbit, it might not be so bad. But according to the European Space Agency’s Space Debris Office, there are estimated to be about 36,500 orbiting artificial objects larger than 10 cm (4 inches) across, such as defunct satellites and rocket stages. There are also around a million between 1 cm and 10 cm, and 330 million measuring 1 mm to 1 cm.

Most of these items are in low Earth orbit. Because of the high speeds involved, even a speck of paint can pit an ISS window and a marble-sized object could penetrate a pressurized module.

The ISS modules are somewhat protected by multi-layer shielding to lessen the probability of a puncture and depressurization. But there remains a risk that such an event could occur before the ISS reaches the end of its lifetime around the end of the decade.

 

Watching the skies

Of course, no one has the technology to track every piece of debris, and we also don’t possess the ability to eliminate all that junk. Nevertheless, possible methods for removing larger pieces from orbit are being investigated.

Meanwhile, nearly 30,000 pieces larger than 10 cm are being tracked by organizations around the world such as the US Space Surveillance Network.

Here in Australia, space debris tracking is an area of increasing activity. Multiple organizations are involved, including the Australian Space Agency, Electro Optic Systems, the ANU Institute for Space, the Space Surveillance Radar System, the Industrial Sciences Group, and the Australian Institute for Machine Learning with funding from the SmartSat CRC.

In addition, the German Aerospace Center (DLR) has a SMARTnet facility at the University of Southern Queensland’s Mt Kent Observatory dedicated to monitoring geostationary orbit at a height of around 36,000km – the home of many communication satellites, including those used by Australia.

One way or another, we will eventually have to clean up our space neighborhood if we want to continue to benefit from the nearest regions of the ‘final frontier’.

Mark Rigby, Adjunct Research Fellow, University of Southern Queensland and Brad Carter, Professor (Physics), University of Southern Queensland.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

 

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