Major damage reported after building explosion in Wheatley, Ont.

The incident came nearly three months after a state of emergency was declared in the same area after officials said a naturally occurring hydrogen sulphide gas leak was detected.

NOTHING NATURAL ABOUT H2SO4

IT'S A GAS UNDER PRESSURE
Nick Westoll 8 hrs ago

© Handout / Greg Hetherington A heavily damaged building can be seen in Wheatley, Ont.

Multiple buildings have been damaged after an explosion in Wheatley, Ont. Thursday evening, officials say.

According to a post on the Chatham-Kent Fire Department Twitter account just before 7:20 p.m. on Thursday, crews were called to the intersection of Erie Street and Talbot Road.

Chatham--Kent--Leamington MPP Rick Nicholls posted a message on his personal Facebook page Thursday evening saying there were "multiple injuries" and seven paramedic crews were sent to the scene.

"Buildings destroyed on main [street]," he wrote.

"Cause not yet determined. I’ve reached out to the Minister of Natural [Resources] and Forestry and forwarded pics just in case the determination is a gas leak."

However, paramedics or other officials didn't release any further information on injuries as of Wednesday night.

Photos posted on social media Thursday evening appeared to show damage to multiple properties.

Fire department officials said residents near the scene who haven't been evacuated should be prepared to leave.

An update issued by Ontario Provincial Police said the Wheatley Area Arena was being opened for people who were displaced by the explosion.

Crews with the Ontario government's hazardous materials and urban search and rescue teams were called to assist.

Read more: State of emergency declared in Wheatley, Ont., after hydrogen sulphide leak

Wheatley is located just north of Point Pelee National Park and approximately 35 minutes southwest of Chatham.

Global News contacted fire and police officials to get additional information on the situation and further details about the circumstances leading up to the explosion, but representatives weren't immediately available for comment.

The incident came nearly three months after a state of emergency was declared in the same area after officials said a naturally occurring hydrogen sulphide gas leak was detected

Titan-in-a-glass experiments hint at mineral makeup of Saturn moon

by American Chemical Society

True-color image of layers of haze in Titan's atmosphere. Credit: NASA

Titan, Saturn's largest moon, is a natural laboratory to study the origins of life. Like Earth, Titan has a dense atmosphere and seasonal weather cycles, but the chemical and mineralogical makeup are significantly different. Now, earthbound researchers have recreated the moon's conditions in small glass cylinders, revealing fundamental properties of two organic molecules that are believed to exist as minerals on Titan.


The researchers will present their results today at the fall meeting of the American Chemical Society (ACS).

"Simple organic molecules that are liquid on Earth are typically solid icy mineral crystals on Titan because of its extremely low temperatures, down to -290 F," says Tomče Runčevski, Ph.D., the project's principal investigator. "We found that two of the molecules likely to be abundant on Titan—acetonitrile (ACN) and propionitrile (PCN)—occur predominantly in one crystalline form that creates highly polar nano surfaces, which could serve as templates for the self-assembly of other molecules of prebiotic interest."

Most of what we know now about this icy world is thanks to the 1997-2017 Cassini-Huygens mission to Saturn and its moons. From that mission, scientists know that Titan is a compelling place to study how life came about. Like Earth, Titan has a dense atmosphere, but it is mostly made up of nitrogen, with a touch of methane. It is the only known body in space, other than Earth, where clear evidence of stable pools of surface liquid has been found. Fueled by the sun's energy, Saturn's magnetic field and cosmic rays, both nitrogen and methane react on Titan to produce organic molecules of various sizes and complexities. ACN and PCN are believed to be present in the moon's characteristic yellow haze as aerosols, and they rain down on the surface, settling as solid chunks of minerals.

The properties of these molecules on Earth are well known, but their characteristics under Titan-like conditions have not been studied until now. "In the lab, we recreated conditions on Titan in tiny glass cylinders," Runčevski says. "Typically, we introduce water, which freezes into ice as we lower the temperature to simulate the Titan atmosphere. We top that with ethane, which becomes a liquid, mimicking the hydrocarbon lakes that Cassini-Huygens found." Nitrogen is added to the cylinder, and ACN and PCN are introduced to simulate the atmospheric rainfall. The researchers then raise and lower the temperatures slightly to imitate the temperature swings on the surface of the moon.

The crystals that formed were analyzed using synchrotron and neutron diffraction instrumentation, spectroscopic experiments and calorimetric measurements. The work, supported by calculations and simulations, involved Runčevski's team from Southern Methodist University, as well as scientists from Argonne National Laboratory, the National Institute of Standards and Technology, and New York University.

"Our research revealed a lot about the structures of planetary ices that was previously unknown," Runčevski says. "For example, we found that one crystalline form of PCN does not expand uniformly along its three dimensions. Titan goes through temperature swings, and if the thermal expansion of the crystals is not uniform in all directions, it may cause the moon's surface to crack." Such detailed knowledge of these minerals could help the team better understand what the surface of Titan is like.

Runčevski is now preparing crystals of ACN, PCN, and ACN and PCN mixtures to obtain detailed spectra. "Scientists will then be able to compare these known spectra to the spectral library collected by Cassini-Huygens and assign unidentified bands," he says. The studies will help confirm the mineral makeup on Titan and will likely provide insights for researchers working on an upcoming NASA mission to Titan, launching in 2027.


Explore further'Titans in a jar' could answer key questions ahead of NASA's space exploration
More information: Simple nitriles as putative cryominerals on Titan, Saturn's moon, ACS Fall 2021.
Provided by American Chemical Society

Moon-in-a-jar recreates the hazy atmosphere of Titan, Saturn's largest moon


By Nicoletta Lanese

SPACE.COM


Beneath Titan's dense yellow atmosphere, rivers of methane and ethane run over the moon's surface. (Image credit: Getty / MARK GARLICK / SCIENCE PHOTO LIBRARY)

Scientists recreated the unique chemical conditions found on Titan, Saturn's largest moon, in tiny glass cylinders here on Earth, and the experiment revealed previously unknown features of the moon's mineral makeup.

Titan is the second-largest moon in the solar system, behind Jupiter's Ganymede, and sports a dense atmosphere of mostly nitrogen with a dash of methane, according to Space.com. This yellowish haze hovers around minus 290 degrees Fahrenheit (minus 180 degrees Celsius). Below the atmosphere, lakes, seas and rivers of liquid methane and ethane cover Titan's icy crust, particularly near the poles. And similar to liquid water on Earth, these natural gases take part in a cycle in which they evaporate, form clouds and then rain down on the moon's surface.

Titan's dense atmosphere, surface liquid and seasonal weather cycles make the frigid moon somewhat similar to Earth, and like our planet, the moon is known to have organic molecules that contain carbon, hydrogen and oxygen, according to NASA. Because of this organic chemistry taking place on Titan, scientists think the moon could serve as a massive laboratory to study chemical reactions that occurred on Earth before the emergence of life on the planet, Space.com previously reported.

Related: Moon birth and methane weather: Cassini's 7 oddest Saturn finds

But only one spacecraft, Cassini, has observed Saturn and its moons in detail, making it tough to do Earthbound research on the wacky chemistry found on Titan. So recently, a team of scientists set out to simulate Titan in a test tube.

The team first placed liquid water in small glass cylinders and cranked down the temperature to Titan-like conditions, the researchers said in a statement. This water froze to mimic Titan's icy crust. The team then introduced ethane to the tube, which became liquid like the lakes on Titan's surface. Finally, they added nitrogen to stand in for Titan's atmosphere and then varied the temperature of the tube ever so slightly, to simulate the variations in temperature on Titan's surface and in different layers of its atmosphere.

In their recent study, presented Thursday (Aug. 26) at the fall meeting of the American Chemical Society, the team then added two compounds, called acetonitrile (ACN) and propionitrile (PCN). Data from the Cassini mission suggest that these compounds are abundant on Titan, principal investigator Tomče Runčevski, an assistant professor in the Department of Chemistry at Southern Methodist University in Dallas, told Live Science.

Most previous studies examined these two compounds separately, in their pure forms, but Runčevski's team wanted to see what would occur when the compounds mixed and mingled, as they might on Titan. As opposed to working with each compound separately, "if you mix them together ... there might be a completely different outcome in structure, so how the molecules will organize, and how the molecules will crystallize," or phase into a solid form, Runčevski said.


And the team found that, when both present in Titan-like conditions, ACN and PCN behave quite differently than either compound in isolation. Namely, the temperatures at which the compounds melted or crystallized shifted drastically, on the order of tens of kelvins (hundreds of degrees Fahrenheit or Celsius).


Related: 6 most likely places for alien life in the solar system


These melting and crystallization points would be relevant in Titan's hazy yellow atmosphere. The various layers of the atmosphere differ in temperature depending on their altitude above the moon's surface, so to understand how chemicals behave throughout the haze, the new study suggests that these temperature variations need to be taken into account, Runčevski said.


In addition, the team found that, when ACN and PCN crystallize, they adopt different crystal structures depending on whether they're alone or in the presence of the other compound. Crystals form when the individual molecules within a compound snap into a highly organized structure. While the building blocks of that structure — the molecules — remain the same, depending on factors such as temperature, they can end up snapping together in slightly different configurations, Runčevski said.

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These variations in crystal structure are known as "polymorphs," and when on their own, ACN and PCN adopt one polymorph at high temperatures and another at low temperatures. But "what we notice is that if we have a mixture, the stability of the high-temperature and low-temperature [polymorphs] can be, in a way, switched," Runčevski said.

These fine details of when and how the compounds achieve a stabilized structure "can really change our understanding of what kind of minerals we might encounter on Titan," in terms of what polymorphs they likely adopt on the moon, he said. This in turn can shape what chemical reactions take place between these and other compounds on Titan.

The new study is limited in that it doesn't account for all of the chemicals present on Titan, and so can capture only a simplified picture of what actually happens on the moon, Runčevski said.

"It's important for us as scientists on Earth ... to create these models with increasing complexity, and one day to reach models that are really significant and can really help us further understand the surface of Titan," he said.

NASA's Dragonfly mission, set to launch in 2026 and arrive at Saturn in 2034, may provide more on-the-ground information about the mineral makeup of Titan. However, Runčevski suspects that the crystals his team has observed likely form around the edge of Titan's lakes, cropping up as the liquid ethane in the lakes evaporates and leaves those compounds behind on the shoreline. At this point, it's unclear whether the Dragonfly mission might focus on this specific aspect of the Titanian environment, but "nonetheless, [the mission] is super exciting, and we will learn so much more about Titan," he said.

Originally published on Live Science.

This Fast Radio Burst Repeats in a Strict Pattern, And We Still Can't Figure Out Why

Visualization of the blue short-wavelength and red long-wavelength bursts. (Joeri van Leeuwen)
SPACE

MICHELLE STARR

26 AUGUST 2021

After taking new radio observations, astronomers have ruled out a leading explanation for the cyclic nature of a particularly curious repeating space signal.

The signal in question is FRB 20180916B, which repeats with a 16.35-day periodicity. According to existing models, this could result from interactions between closely orbiting stars; however, the new detections - which include fast radio burst (FRB) observations at the lowest frequencies yet - do not make sense for such a binary system.

"Strong stellar winds from the companion of the fast radio burst source were expected to let most blue, short-wavelength radio light escape the system. But the redder long-wavelength radio should be blocked more, or even completely," said astrophysicist Inés Pastor-Marazuela of the University of Amsterdam and ASTRON in the Netherlands.

"Existing binary-wind models predicted the bursts should shine only in blue, or at least last much longer there. But we saw two days of bluer radio bursts, followed by three days of redder radio bursts. We rule out the original models now - something else must be going on."

Fast radio bursts are one of the most fascinating mysteries in the cosmos. They're extremely short bursts of very powerful short-wavelength radio waves - as in, just milliseconds in duration, and discharging as much energy as 500 million Suns in that time. Most of the FRB sources we've detected have only been seen once; this makes them unpredictable and hard to study.

A few FRB sources have been detected repeating, although most have done so erratically. FRB 20180916B is one of the two exceptions found repeating on a cycle, which makes it an excellent case for learning more about these mysterious events.

Last year, we also got a major lead on what could be causing FRBs - the first such signal detected coming from within the Milky Way. It was spat out by a magnetar, a type of neutron star with an insanely powerful magnetic field.

But that doesn't mean the case is entirely solved. We don't know why some FRBs repeat, and others don't, for instance - and why, for the repeating FRBs, periodicity has only been detected rarely.

When FRB 20180916B was found to repeat on a cycle, one of the leading explanations was that the neutron star emitting the burst was in a binary system with a 16.35-day orbit. If this were the case, then lower-frequency, longer radio wavelengths should be altered by the charged wind of particles surrounding the binary.

Pastor-Marazuela and her colleagues used two telescopes to make simultaneous observations of the FRB - the Low Frequency Array (LOFAR) radio telescope, and the Westerbork Synthesis Radio Telescope, both headquartered in the Netherlands. When they analyzed the data, they found redder wavelengths in the LOFAR data - meaning that binary winds could not be present to block them.

Nor, for that matter, could other low-frequency absorbing or scattering mechanisms, such as dense electron clouds.

"The fact that some fast radio bursts live in clean environments, relatively unobscured by any dense electron mist in the host galaxy, is very exciting," said astronomer Liam Connor of the University of Amsterdam and ASTRON.

"Such bare fast radio bursts will allow us to hunt down the elusive baryonic matter that remains unaccounted for in the Universe."

So if the binary explanation is ruled out, what could be causing the periodicity? Well, it's still not aliens, sorry.

One explanation suggested last year involves a single object, such as a rotating magnetar or pulsar. This was thought to be a poorer fit for the data than binary wind of charged particles, since those objects have a wobbling rotation that produces periodicity, and none are known to wobble that slowly.

But with the binary wind off the table, thanks to the LOFAR and Westerbork observations, a slowly wobbling magnetar is back on it. And this suggests we still have quite a bit to learn about both magnetars and FRBs.

"An isolated, slowly rotating magnetar best explains the behavior we discovered," Pastor-Marazuela said.

"It feels a lot like being a detective - our observations have considerably narrowed down which fast radio burst models can work."

The research has been published in Nature.

 

Advanced civilizations could be using Dyson spheres to collect energy from black holes

by Andy Tomaswick, Universe Today

Example of a partial Dyson sphere around a star. Credit: Kevin Gill

Black holes are more than just massive objects that swallow everything around them—they're also one of the universe's biggest and most stable energy sources. That would make them invaluable to the type of civilization that needs huge amounts of power, such as a Type II Kardashev civilization. But to harness all of that power, the civilization would have to encircle the entire black hole with something that could capture the power it is emitting.

One potential solution would be a Dyson sphere—a type of stellar mega-engineering project that encapsulates an entire star (or, in this case, a black hole) in an artificial sheath that captures all of the energy the object at its center emits. But even if it was able to capture all of the energy the black hole emits, the sphere itself would still suffer from heat loss. And that heat loss would make it visible to us, according to new research published by an international team led by researchers at the National Tsing Hua University in Taiwan.

Obviously, no such structure has yet been detected. Still, the paper proves that it is possible to do so, despite no visible light making it past the sphere's surface and a black hole's reputation for being light sinks rather than light sources. To understand how we would detect such a system, first, it would be helpful to understand what that system would be designed to do.

The authors study six different energy sources that a potential Dyson sphere could collect around a black hole. They are the omnipresent cosmic microwave background radiation (which would be washing over the sphere no matter where it was placed), the black hole's Hawking radiation, its accretion disk, its Bondi accretion, its corona, and its relativistic jets.

Credit: Universe Today

Some of these energy sources are much more high-powered than others, with the energy from the black hole's accretion disk leading the pack in terms of potential energy captures. Other types of energy would require completely different engineering challenges, such as capturing the kinetic energy of the relativistic jets that shoot out from the black hole's poles. Size obviously plays a large factor in how much energy these black holes emit. The authors primarily focus on stellar-mass black holes as a good point of comparison against other potential energy sources. At that size, the accretion disk alone would provide hundreds of times the energy output of a main-sequence star.

It would be impossible to build a Dyson sphere around any object that size with current known materials. But the type of civilization that would be interested in taking on such an engineering challenge would most likely have much stronger materials than we do today. Alternatively, they could work with known materials to create a Dyson swarm or Dyson bubble, which doesn't require as much material strength but does lose some of the energy that a complete sphere would capture, and adds multiple layers of complexity when coordinating orbital paths and other factors. Any such structure would have to be outside the accretion disk to get the full benefit from the energy the black hole emits.

Composite image of Centaurus A, our galaxy’s central supermassive black hole, showing the jets emerging together with the associated gamma radiation. Credit: ESO/WFI (Optical); MPIfR/ESO/APEX/A.Weiss et al. (Submillimetre); NASA/CXC/CfA/R.Kraft et al. (X-ray), H.E.S.S. collaboration (Gamma)

Even a single sphere around a single stellar-mass black hole would be enough to push any civilization that created it into Type II territory, giving it a level of power output unimaginable with current technology. But even such a potent civilization most likely won't be able to bend the laws of physics. No matter the power level, some of it will be lost to heat.

Credit: Universe Today

To astronomers, heat is simply another form of light—infrared, to be exact. And according to the researchers, the heat emitted by a Dyson sphere around a black hole should be detectable by our current crop of telescopes, such as the Wide Field Infrared Survey Explorer and the Sloan Digital Sky Survey, to a distance of about 10kpc at least. That's about 1/3 of the distance across the entire Milky Way. No matter how close they were, they wouldn't appear like traditional stars but could be detectable using the radial velocity method commonly used to find exoplanets.

While this is useful theoretical work, there certainly hasn't been any evidence of any such structure existing yet—Fermi's Paradox still holds. But given all the data that we're already collecting these telescopes, it might be interesting to scan through them one more time to check if there happens to be heat emanating from a place where it wouldn't be expected. It would be worth the time to at least look for what could be such a fundamentally ground-breaking discovery.

Astronomers see first hint of the silhouette of a spaghettified star

More information: Tiger Yu-Yang Hsiao et al, A Dyson sphere around a black hole, Monthly Notices of the Royal Astronomical Society (2021). DOI: 10.1093/mnras/stab1832

Journal information: Monthly Notices of the Royal Astronomical Society 

Provided by Universe Today 

 

Unraveling the mystery of brown dwarfs

by University of Geneva

This artist’s illustration represents the five brown dwarfs discovered with the satellite

 TESS. These objects are all in close orbits of 5-27 days (at least 3 times closer than

 Mercury is to the sun) around their much larger host stars. 

Credit: CC BY-NC-SA 4.0 - Thibaut Roger - UNIGE

Brown dwarfs are astronomical objects with masses between those of planets and stars. The question of where exactly the limits of their mass lie remains a matter of debate, especially since their constitution is very similar to that of low-mass stars. So how do we know whether we are dealing with a brown dwarf or a very low mass star? An international team, led by scientists from the University of Geneva (UNIGE) and the Swiss National Centre of Competence in Research (NCCR) PlanetS, in collaboration with the University of Bern, has identified five objects that have masses near the border separating stars and brown dwarfs that could help scientists understand the nature of these mysterious objects. The results can be found in the journal Astronomy & Astrophysics.

Like Jupiter and other giant gas planets, stars are mainly made of hydrogen and helium. But unlike gas planets, stars are so massive and their gravitational force so powerful that hydrogen atoms fuse to produce helium, releasing huge amounts of energy and light.

'Failed stars'

Brown dwarfs, on the other hand, are not massive enough to fuse hydrogen and therefore cannot produce the enormous amount of light and heat of stars. Instead, they fuse relatively small stores of a heavier atomic version of hydrogen: Deuterium. This process is less efficient and the light from brown dwarfs is much weaker than that from stars. This is why scientists often refer to them as "failed stars."

"However, we still do not know exactly where the mass limits of brown dwarfs lie, limits that allow them to be distinguished from low-mass stars that can burn hydrogen for many billions of years, whereas a brown dwarf will have a short burning stage and then a colder life," points out Nolan Grieves, a researcher in the Department of Astronomy at the UNIGE's Faculty of Science, a member of the NCCR PlanetS and the study's first author. "These limits vary depending on the chemical composition of the brown dwarf, for example, or the way it formed, as well as its initial radius," he explains.

To get a better idea of what these mysterious objects are, we need to study examples in detail. But it turns out that they are rather rare. "So far, we have only accurately characterized about 30 brown dwarfs," says the Geneva-based researcher. Compared to the hundreds of planets that astronomers know in detail, this is very few. All the more so if one considers that their larger size makes brown dwarfs easier to detect than planets.

New pieces of the puzzle

Today, the international team characterized five companions that were originally identified with the Transiting Exoplanet Survey Satellite (TESS) as TESS objects of interest (TOI) - TOI-148, TOI-587, TOI-681, TOI-746 and TOI-1213. These are called "companions" because they orbit their respective host stars. They do so with periods of 5 to 27 days, have radii between 0.81 and 1.66 times that of Jupiter, and are between 77 and 98 times more massive. This places them on the borderline between brown dwarfs and stars.

These five new objects therefore contain valuable information. "Each new discovery reveals additional clues about the nature of brown dwarfs and gives us a better understanding of how they form and why they are so rare," says Monika Lendl, a researcher in the Department of Astronomy at the UNIGE and a member of the NCCR PlanetS.

One of the clues the scientists found to show these objects are brown dwarfs is the relationship between their size and age, as explained by François Bouchy, professor at UNIGE and member of the NCCR PlanetS: "Brown dwarfs are supposed to shrink over time as they burn up their deuterium reserves and cool down. Here we found that the two oldest objects, TOI 148 and 746, have a smaller radius, while the two younger companions have larger radii."

Yet these objects are so close to the limit that they could just as easily be very low-mass stars, and astronomers are still unsure whether they are brown dwarfs. "Even with these additional objects, we still lack the numbers to draw definitive conclusions about the differences between brown dwarfs and low-mass stars. Further studies are needed to find out more," concludes Grieves.

Observations detect a brown dwarf orbiting the star TOI–1278

More information: Nolan Grieves et al, Populating the brown dwarf and stellar boundary: Five stars with transiting companions near the hydrogen-burning mass limit, Astronomy & Astrophysics (2021). DOI: 10.1051/0004-6361/202141145

Journal information: Astronomy & Astrophysics 

Provided by University of Geneva 

Oort Cloud News: How Many Comets From Elsewhere?

Posted by
Kelly Kizer Whitt
August 26, 2021

Comet Borisov, spotted in 2019, was a visitor from another solar system. It’s the 2nd known interstellar object, and 1st known interstellar comet. But could there be billions more interstellar comets in the Oort Cloud?

 Image via NASA/ ESA/ D. Jewitt (UCLA).

Oort Cloud news

Astronomers picture the Oort Cloud as a cloud of comets on the farthest outskirts of our solar system. Dutch astronomer Jan Oort theorized its existence in 1950. He said long-period comets are sometimes knocked from their distant orbits in the Oort Cloud (perhaps by passing stars). That’s how they end up in orbits that bring them near our sun. If it exists, Oort thought, this comet cloud is made of material left over from our solar system’s formation 4.5 billion years ago. But is it? Scientists now generally agree that billions of comets must reside in the Oort Cloud. But what fraction of these comets might have originated in other star systems? This week (August 22, 2021), two scientists said the answer might be … most of them.

The two scientists are Amir Siraj and Avi Loeb, both of Harvard. Loeb is also author of Extraterrestrial, the First Sign of Intelligent Life Beyond Earth, which proposes that the first known interstellar visitor (1I/ ‘Oumuamua), might have been an artificial object, made by an advanced extraterrestrial civilization. The peer-reviewed journal Monthly Notices of the Royal Astronomical Society published these scientists’ new study about the Oort Cloud on August 23, 2021.

The study focuses on a realm of space that lies between 1,000 and 100,000 times Earth’s distance from our sun. In fact, some astronomers estimate the Oort Cloud may extend out nearly as far as a light-year from our sun. By contrast, the nearest star to our sun is about 4 light-years away.

The Oort Cloud is so far out from the sun that its existence is still hypothetical 

(though it’s logical  PROBABLE to believe it does exist). The cloud is visualized as stretching from 1,000 times the Earth-sun distance to about 100,000 times that distance. Image via NASA.

Comet Borisov, the first interstellar comet

Astronomers spotted the first known interstellar object, ‘Oumuamua, in 2017. In 2019, they spotted a second object from interstellar space. This one looked more distinctly comet-like. Astronomers call it 2I/ Borisov, or sometimes just Comet Borisov. Traveling at 110,000 miles per hour (177,000 kph), Comet Borisov passed closest to the sun and Earth in December 2019, displaying a tail 14 times the size of Earth. Then it headed back toward interstellar space.

It’s the information drawn from Comet Borisov that enabled Siraj and Loeb to speculate that the Oort Cloud consists mostly of interstellar visitors. The scientists admit the information on Comet Borisov still holds a degree of uncertainty. But, even with these uncertainties, the scientists said their calculations show that interstellar objects are more numerous than solar system objects in the Oort Cloud. Siraj commented in a statement:

Before the detection of the first interstellar comet, we had no idea how many interstellar objects there were in our solar system. But theory on the formation of planetary systems suggests that there should be fewer visitors than permanent residents. Now we’re finding that there could be substantially more visitors.

Interstellar objects are dark and distant

If the Oort Cloud contains perhaps billions of interstellar objects, why haven’t we seen more of them? Siraj said it’s because we don’t yet have the technology to see them. Consider first how far away the Oort Cloud is. The Earth-sun distance (93 million miles, or 150 million km) is called an astronomical unit (AU) from the sun. Tiny Pluto is about 40 AU from the sun. The even-smaller comets in the Oort Cloud are some 1,000 to 100,000 AU away. But remember that the comets don’t shine by their own light. They only reflect our sun’s light. So a comet in the Oort Cloud, interstellar or otherwise, is simply too far from the sun, too dim and too small for us to see directly. Thus we see comets – and speculate about an Oort Cloud – only thanks to those comets that are dislodged from the Oort Cloud and come hurtling in to our part of the solar system.
Could there be interstellar objects closer to Earth?

Matthew Holman, former director of the Center for Astrophysics Minor Planet Center, who did not participate in the research, wondered if the abundance of interstellar visitors in the farthest regions of the solar system could translate to some interstellar visitors closer to the sun. He said:

These results suggest that the abundances of interstellar and Oort cloud objects are comparable closer to the sun than Saturn. This can be tested with current and future solar system surveys. When looking at the asteroid data in that region, the question is: Are there asteroids that really are interstellar that we just didn’t recognize before?

There are asteroids that scientists have detected but not tracked over the years. Holman mused:
We think they are asteroids, then we lose them without doing a detailed look.

Co-author Loeb added:
Interstellar objects in the planetary region of the solar system would be rare, but our results clearly show they are more common than solar system material in the dark reaches of the Oort cloud.

Future searches

The Vera C. Rubin Observatory, currently under contruction in Chile, should help astronomers find more visitors from outside our solar system. Siraj commented that the new observatory will:

… blow previous searches for interstellar objects out of the water.

First light for the Vera Rubin’s engineering camera is expected in October 2022 – and full survey operations expected perhaps a year later.

Also slated for 2022, the Transneptunian Automated Occultation Survey will operate three medium-sized telescopes at the Observatorio Astronomico Nacional at San Pedro Mártir, a mountain range in Baja California, México. This system is specifically designed to find small bodies on the outer edges of our solar system. Perhaps it will unlock the door to more interstellar objects. 

Siraj said:

Our findings show that interstellar objects can place interesting constraints on planetary system formation processes. [A large number of interstellar objects in the Oort Cloud] requires a significant mass of material to be ejected [from our solar system] in the form of planetesimals. Together with observational studies of protoplanetary disks [disks around newly forming stars] and computational approaches to planet formation, the study of interstellar objects could help us unlock the secrets of how our planetary system – and others – formed.

Bottom line: Scientists’ calculations show that the majority of comets in the Oort Cloud may be interstellar objects, or visitors from beyond our solar system.

Source: Interstellar objects outnumber Solar system objects in the Oort cloud

Preprint at arXiv: Interstellar Objects Outnumber Solar System Objects in the Oort Cloud

Via Harvard and Smithsonian Center for Astrophysics

Interstellar comets visit our solar system more frequently than thought

By Tereza Pultarova about 13 hours ago

Just because we don't see them doesn't mean they're not here.

The outer solar system might be full of comets from other stars. 

(Image credit: NOIRLab/NSF/AURA/J. da Silva)

Comets from other star systems, such as 2019 Borisov, visit the sun's neighborhood more frequently than scientists had thought, a new study suggests.

The study, based on data gathered as Borisov zipped by Earth at a distance of about 185 million miles (300 million kilometers) in late 2019, suggests that the comet repository in the far outer solar system known as the Oort Cloud might be full of objects that were born around other stars. In fact, the authors of the study suggest that the Oort Cloud might contain more interstellar material than domestic stuff. 

Named after famous Dutch astronomer Jan Oort, who first proved its existence in the 1950s, the Oort Cloud is a spherical shell of small objects — asteroids, comets and fragments — far beyond the orbit of Neptune. The cloud's inner edge is thought to begin about 2,000 astronomical units (AU) from the sun, and its outer edge lies about 200,000 AU away. (One AU is the average Earth-sun distance — about 93 million miles, or 150 million kilometers.)

No spacecraft has ever visited the Oort Cloud, and it will take 300 years for NASA's farflung Voyager 1 probe to even glimpse the cloud's closest portion. 

Related: Interstellar Comet Borisov Shines in New Photo

Astronomers have very limited tools to study this intriguing world, as objects in the Oort Cloud don't produce their own light. At the same time, these objects are too far away to reflect much of the sun's light. 

So how exactly did the scientists figure out that there must be so many interstellar objects in the Oort Cloud, and what did Borisov have to do with it?

Amir Siraj, a graduate student at Harvard University's Department of Astronomy and lead author of the study, told Space.com in an email that he could calculate the probability of foreign comets visiting the solar system simply based on the fact that the Borisov comet had been discovered. 

"Based on the distance that Borisov was detected at, we estimated the implied local abundance of interstellar comets, just like the abundance of 'Oumuamua-like objects was calibrated by the detection of 'Oumuamua," Siraj said. 

The mysterious 'Oumuamua, first spotted by astronomers in Hawaii in October 2017, was the first interstellar body ever detected within our own solar system. The object passed Earth at a distance of 15 million miles (24 million km), about one-sixth of the distance between our planet and the sun. An intense debate about 'Oumuamua's nature ensued, as it wasn't clear at first whether the object was a comet or an asteroid.

Even the detection of a single object can be used for statistical analysis, Siraj said. The so-called Poisson method, which the astronomers used, calculates the probability of an event happening in a fixed interval of time and space since the last event. 

Taking into consideration the gravitational force of the sun, Siraj and co-author Avi Loeb, an astronomer at Harvard, were able to estimate the probability of an interstellar comet making its way to Earth's vicinity. They found that the number of interstellar comets passing through the solar system increases with the distance from the sun. 

"We concluded that, in the outer reaches of the solar system, and even considering the large uncertainties associated with the abundance of Borisov-like objects, transitory interstellar comets should outnumber Oort Cloud objects (comets from our own solar system)," Siraj added.

So why have astronomers seen just one interstellar comet so far? The answer is technology. Telescopes have only recently gotten powerful enough to be able to spot those small but extremely fast-travelling bodies, let alone study them in detail. 

"Before the detection of the first interstellar comet, we had no idea how many interstellar objects there were in our solar system," said Siraj. "Theory on the formation of planetary systems suggests that there should be fewer visitors than permanent residents. Now we're finding that there could be substantially more visitors."

The astronomers hope that with the arrival of next-generation telescopes, such as the Vera C. Rubin Observatory, currently under construction in Chile, the study of extrasolar comets and asteroids will truly take off. 

The new study was published in the journal Monthly Notices of the Royal Astronomical Society on Monday (Aug 24).

Secrets of Earth’s largest carbon sink revealed by synchrotron research


A team of scientists has discovered microscopic dissolution seams that dissolve about 10 percent of the carbon in ancient deep-sea limestones where most of the world’s carbon is stored.

Ancient deep-sea limestones’ role in carbon cycle probed

Sophisticated synchrotron X-ray microscopy showed thousands of micro-dissolution seams in limestone layers

Micro-dissolution seams dissolve about 10 per cent of the total carbon of the limestones studied

The research team, led by Dr Christoph Schrank from QUT’s School of Earth and Atmospheric Sciences, Dr Michael Jones from QUT’s Central Analytical Research Facility, and Australian Nuclear Science and Technology Organisation (ANSTO) synchrotron scientist Dr Cameron Kewish, published their findings in the Nature journal Communications Earth and Environment.

Dr Schrank said deep-sea limestones had been the Earth’s largest carbon sink for the past 180 million years because they trapped most of the planet’s carbon.

“However, their contribution to the long-term carbon cycle is poorly quantified,” he said.

“Measuring the amount of carbon captured in deep-sea limestones is fundamental to understanding the long-term carbon cycle – how carbon is exchanged between the atmosphere, the oceans, the biosphere, and the rocky bones of the Earth itself over thousands to millions of years.

“Scientists try to unravel the carbon cycle in order to understand important processes such as climate change. To do that, we need to estimate how much carbon the limestones can really trap.”

Dr Christoph Schrank, front, with a deep sea limestone sample and co-researchers l/r- Dr Luke Nothdurft, Dr Craig Sloss, Dr Michael Jones

Dr Schrank said they used high-resolution chemical and structural maps to work out that these micro-dissolution seams were ultrathin layers along which large amounts of calcium carbonate had dissolved away.

“While individual micro-dissolution seams are much thinner than a human hair, their spacing is incredibly dense – the average distance between two seams is about a hair’s breadth,” Dr Schrank said.

“We put this geometric information and mass-balance estimates together to work out that the micro-dissolution seams dissolved about 10 per cent of the total carbon of the limestones in our study.

“Published mathematical models of limestone dissolution and geological evidence suggest that this dissolution process occurred within 10 cm to 10 m below the sediment over 50 to 5000 years.”

Where the dissolved carbon goes is not yet known for sure. Dr Schrank said the limestones they studied were formed near an extremely tectonically active region off the North Island’s east coast

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Limestone rocks on east coast of North Island of New Zealand

“For the past 25 million years, and even today, this region is regularly shaken up by earthquakes, which are known to stir up sediments at the ocean floor.

“We suggest that the dissolved carbon could be returned to the ocean when the seafloor is disturbed by earthquakes or underwater landslides.”

The research team from QUT, ANSTO, University of Queensland, University of New South Wales, and La Trobe University discovered the micro-seams using the extremely powerful X-rays of the ANSTO Australian Synchrotron.


“The team at ANSTO, QUT, and La Trobe University developed cutting-edge X-ray microscopy techniques at the Australian Synchrotron over the past decade to probe the chemical composition and structure of materials down to tens of nanometres,” Dr Kewish said.

“The synchrotron produces light more than a million times brighter than the sun, and X-ray microscopy allows us to see features that have previously remained invisible.”

Australian Synchrotron THERE IS ONE IN SASKATCHEWAN,CANADA

Dr Jones said: “Applying these novel techniques to sections of 55-million-year-old limestones from the east coast of the North Island of New Zealand enabled us to see, for the first time, that layers of limestone contain thousands of tiny micro-dissolution seams that are practically invisible to other microscopic techniques.”

Dr Schrank said the team planned to examine other limestone deposits around the world with high-resolution synchrotron techniques to better understand how micro-dissolution contributes to carbon exchange between the sediment and the ocean.

Micro-scale dissolution seams mobilise carbon in deep-sea limestones was published in the Nature journal Communications Earth and Environment.