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ESO/MPIfR APEX high on the Chajnantor plateau in Chile’s Atacama region, at an altitude of over 4,800 m (15,700 ft)
An international team of researchers have discovered a dense, cold gas that’s been shot out from the center of the Milky Way “like bullets”.
Exactly how the gas has been ejected is still a mystery, but the research team, including Professor Naomi McClure-Griffiths from The Australian National University (ANU), say their findings could have important implications for the future of our galaxy.
“Galaxies can be really good at shooting themselves in the foot,” Professor McClure-Griffiths said.
“When you drive out a lot of mass, you’re losing some of the material that could be used to form stars, and if you lose enough of it, the galaxy can’t form stars at all anymore.
“So, to be able to see hints of the Milky Way losing this star forming gas is kind of exciting—it makes you wonder what’s going to happen next!”
The study also raises new questions about what’s happening in our galactic center right now.
“The wind at the center of the Milky Way has been the topic of plenty of debate since the discovery a decade ago of the so-called Fermi Bubbles—two giant orbs filled with hot gas and cosmic rays,” Professor McClure-Griffiths said.
“We’ve observed there’s not only hot gas coming from the center of our galaxy, but also cold and very dense gas.
“This cold gas is much heavier, so moves around less easily.”
The center of the Milky Way is home to a massive black hole, but it’s unclear whether this black hole has expelled the gas, or whether it was blown by the thousands of massive stars at the center of the galaxy.
“We don’t know how either the black hole or the star formation can produce this phenomenon. We’re still looking for the smoking gun, but it gets more complicated the more we learn about it,” lead author Dr. Enrico Di Teodoro from Johns Hopkins University said.
“This is the first time something like this has been observed in our galaxy. We see these kind of processes happening in other galaxies. But, with external galaxies you get much more massive black holes, star formation activity is higher, it makes it easier for the galaxy to expel material.
“And these other galaxies are obviously a long way away, we can’t see them in a lot of detail.
“Our own galaxy is almost like a laboratory that we can actually get into and try to understand how things work by looking at them up close.”
The research has been published in the journal Nature.
The gas was observed using the Atacama Pathfinder EXperiment (APEX) operated by the European Southern Observatory (ESO) in Chile.
ANU is a world-leading university in Australia’s capital city, Canberra. Our location points to our unique history, ties to the Australian Government and special standing as a resource for the Australian people.
Our focus on research as an asset, and an approach to education, ensures our graduates are in demand the world-over for their abilities to understand, and apply vision and creativity to addressing complex contemporary challenges.
We now know just how massive the fastest-growing black hole in the Universe actually is, as well as how much it eats, thanks to new research led by The Australian National University (ANU).
It is 34 billion times the mass of our sun and gorges on nearly the equivalent of one sun every day, according to Dr. Christopher Onken and his colleagues.
“The black hole’s mass is also about 8,000 times bigger than the black hole in the centre of the Milky Way,” Dr. Onken said.
“If the Milky Way’s black hole wanted to grow that fat, it would have to swallow two thirds of all the stars in our Galaxy.”
This giant black hole—known as J2157—was discovered by the same research team in 2018.
“We’re seeing it at a time when the universe was only 1.2 billion years old, less than 10 percent of its current age,” Dr. Onken said.
“It’s the biggest black hole that’s been weighed in this early period of the Universe.”
Exactly how black holes grew so big so early in the life-span of the Universe is still a mystery, but the team is now searching for more black holes in the hope they might provide some clues.
“We knew we were onto a very massive black hole when we realised its fast growth rate,” said team member Dr. Fuyan Bian, a staff astronomer at the European Southern Observatory (ESO).
“How much black holes can swallow depends on how much mass they already have.
“So, for this one to be devouring matter at such a high rate, we thought it could become a new record holder. And now we know.”
The team, including researchers from the University of Arizona, used ESO’s Very Large Telescope in Chile to accurately measure the black hole’s mass.
ESO VLT at Cerro Paranal in the Atacama Desert, •ANTU (UT1; The Sun ), •KUEYEN (UT2; The Moon ), •MELIPAL (UT3; The Southern Cross ), and •YEPUN (UT4; Venus – as evening star). elevation 2,635 m (8,645 ft) from above Credit J.L. Dauvergne & G. Hüdepohl atacama photo,
“With such an enormous black hole, we’re also excited to see what we can learn about the galaxy in which it’s growing,” Dr. Onken said.
“Is this galaxy one of the behemoths of the early Universe, or did the black hole just swallow up an extraordinary amount of its surroundings? We’ll have to keep digging to figure that out.”
ANU is a world-leading university in Australia’s capital city, Canberra. Our location points to our unique history, ties to the Australian Government and special standing as a resource for the Australian people.
Our focus on research as an asset, and an approach to education, ensures our graduates are in demand the world-over for their abilities to understand, and apply vision and creativity to addressing complex contemporary challenges.
26 May 2020
James Giggacher
+61 2 6125 7979
media@anu.edu.au
The DREAMS telescope will help find colliding neutron stars. Image: NASA
A new infrared telescope, to be designed and built by astronomers at The Australian National University (ANU), will monitor the entire southern sky in search of new cosmic events as they take place.
DREAMS – the Dynamic REd All-Sky Monitoring Survey – will be located at the historic Siding Spring Observatory in northern New South Wales.
Siding Spring Mountain with Anglo-Australian Telescope dome visible near centre of image at an altitude of 1,165 m (3,822 ft)
The telescope will be used by researchers all over the globe and propel Australia to the forefront of the emerging field of transient astronomy – the study of cosmic events almost in ‘real time’.
Lead researcher Professor Anna Moore, Director of the ANU Institute for Space (InSpace), said a transient survey of the southern sky in the infrared had never been done and would help find many hidden treasures in the Universe.
“DREAMS will allow us to ‘see’ the Universe in an entirely new way,” Professor Moore said.
“Infrared telescopes can study dusty and distant regions of space that are impenetrable to optical telescopes, unveiling new stars, nebulae, mergers, galaxies, supernovae, quasars and other sources of radiation new to science.
“By monitoring the sky continuously and rapidly, we will be able to search for varying and explosive phenomena. This ‘real-time’ astronomy, which allows us to study events taking place over months, weeks or days instead of millions of years, is a window into the great unknown.
“DREAMS will give us a fresh take on many aspects of the Universe.”
DREAMS consists of a fully automated 0.5m telescope and infrared camera. In each snapshot, DREAMS “sees” 3.75 square degrees (20 times the Moon’s size) and will be able to map the entire southern sky in three clear nights. The telescope is 10 times more powerful than its nearest competitors.
The data captured by DREAMS will help detect the source of gravitational waves, and the collision of neutron stars and black holes.
“DREAMS will enable multi-messenger astronomy – the discovery of new events by observing the sky using different wavelengths of light,” lead research partner Assistant Mansi Kasliwal, from the California Institute of Technology (Caltech), said.
“By doing so it aspires to pinpoint elusive gravitational wave events.
“Neutron star black hole mergers are especially exciting as they create heavy elements that shine in the infrared.”
According to Dr Tony Travoillan, a co-investigator and lead technical manager on the project, DREAMS is innovative and economical.
“Surveying the sky in the infrared has always been limited by the cost of the cameras and not the telescope,” Dr Travouillon, who is based at the ANU Research School of Astrophysics and Astronomy, said.
“The development of infrared cameras using Indium Gallium Arsenide technology, with the help of our collaborators at MIT, has given astronomers an economical alternative that we are the first to implement on a wide field survey.
“We are using six of these cameras on our telescope. It gives us a scalable design that minimises instrument complexity and cost.”
The telescope will be completed in early 2021, with operations beginning soon after. Co-investigator Professor Orsola DeMarco, from Macquarie University, will use simulations to explain coalescing, or merging, stars captured by DREAM.
“I hope the telescope will see merging stars so dusty that they shine brightly in the infrared,” she said.
DREAMS is funded through an Australian Research Council Linkage Infrastructure, Equipment and Facilities award of $632,000 and a cash contribution of $750,000 from ANU and partners the Australian Astronomical Optics, Caltech, the Chinese Academy of Sciences, Curtin University, Swinburne University, Macquarie University, Monash University, MIT, the University of New South Wales, the University of Sydney, and the University of Western Australia.
ANU is a world-leading university in Australia’s capital city, Canberra. Our location points to our unique history, ties to the Australian Government and special standing as a resource for the Australian people.
Our focus on research as an asset, and an approach to education, ensures our graduates are in demand the world-over for their abilities to understand, and apply vision and creativity to addressing complex contemporary challenges.
Stars far, far away could appear a lot closer when viewed through our telescopes thanks to new research from The Australian National University (ANU).
The research has also brought the properties of nearby stars into never before seen precision, and could allow us to catch a rare glimpse of the conditions of planets orbiting them in the future.
PhD researcher Adam Rains used a cutting-edge approach to measure the properties of 16 stars, making them clearer than ever before.
“To put things in perspective, the measurement precision we achieved is like looking at a dollar coin 4,600 km away and measuring its diameter to the nearest 0.25 mm,” Mr Rains said.
“We now know the temperature of these stars to a similar level of precision! For example – this is like measuring a 5,000 degree star to within 50 degrees.
“To do this, we combined the light from multiple telescopes.”
Mr Rains says ordinarily, features like the size and temperature of stars are very difficult to measure directly.
“Most stars are simply too far away, and our current telescopes too small for us to study at the level of detail or resolution we have reached here,” he said.
“The stars we looked at are relatively close in comparison. That’s why this research is so important – so much of our knowledge of stars all over the universe is built upon what we have learnt about the stars closest to us.”
Several of the stars observed for this study have planets around them – making any information collected about them even more valuable.
“By knowing things like how big, how hot, and how bright these stars are, we are also better able to figure out what conditions might be like on any planets orbiting them,” Mr Rains said.
Mr Rains looked at a number of stars like Tau Ceti which have been previously observed by other astronomers, to make sure his results matched up.
The study was carried out using a method called interferometry to harness the power of multiple telescopes.
“Interferometry combines light from a set of separate telescopes to increase their resolution beyond any of the individual telescopes – making the whole greater than the sum of its parts,” Mr Rains said
“Currently the biggest telescopes on the planet have mirrors about 10 metres across. Even larger telescopes are under construction, but there are practical limits on just how big they can get.
“If you can combine the light from separate telescopes you can achieve the resolution of a much larger telescope – without actually building one. It’s like having a 130m telescope.”
For this technique to work, you have to make sure the starlight from the telescopes arrives at the camera at exactly the same time.
This is achieved by having ‘mirror-trains’. Mirrors are placed on carriages that move along a rail system to control when each telescope’s light hits the camera.
“The further apart your telescopes, the longer the rail system you need, but this technique is the only one that lets us study other stars at such high resolution,” Mr Rains said.
Mr Rains’ work was based on observations carried out at the Very Large Telescope facility in Chile, operated by the European Southern Observatory.
ESO VLT at Cerro Paranal in the Atacama Desert, •ANTU (UT1; The Sun ), •KUEYEN (UT2; The Moon ), •MELIPAL (UT3; The Southern Cross ), and •YEPUN (UT4; Venus – as evening star). elevation 2,635 m (8,645 ft) from above Credit J.L. Dauvergne & G. Hüdepohl atacama photo,
ANU is a world-leading university in Australia’s capital city, Canberra. Our location points to our unique history, ties to the Australian Government and special standing as a resource for the Australian people.
Our focus on research as an asset, and an approach to education, ensures our graduates are in demand the world-over for their abilities to understand, and apply vision and creativity to addressing complex contemporary challenges.
The Sun and T UMi are expected to end their days much like U Camelopardalis (pictured).
European Space Agency/Hubble
NASA/ESA Hubble Telescope
Astronomers have witnessed a rare dynamic event they say reinforces predictions about the Sun’s ultimate demise.
The convulsion of T Ursae Minoris (T UMi) – a star similar to the Sun but older and nearer the end of its life – was significant because “the signs of ageing could be directly observed in a star over human timescales,” says Meredith Joyce from the Australian National University.
Dr Meridith Joyce. Lannon Harley, ANU
This supports the idea that the Sun will turn into a red giant and then into an expanding and glowing ring-shaped shell of gas in five billion years, leaving behind a small white dwarf as a remnant.
“It will become much bigger as it approaches death – eating Venus, Mercury and possibly the Earth in the process – before shrinking to become a white dwarf,” says Joyce, who led the international study with László Molnár and László Kiss from the Hungarian Academy of Sciences.
T UMi was born about 1.2 billion years ago, with a mass roughly twice that of the Sun, in the Little Bear constellation more than 3000 light-years from Earth.
The researchers found that over the past few million years, during its last stage of life before its ultimate transition to a white dwarf, it has been undergoing a series of pulses, whereby its size, brightness and temperature have fluctuated enormously.
“Energy production in T UMi has become unstable. During this phase, nuclear fusion flares up deep inside, causing ‘hiccups’ that we call thermal pulses,” says Joyce.
“These pulses cause drastic, rapid changes in the size and brightness of the star, which are detectable over centuries. The pulses of old stars like T UMi also enrich the entire universe with elements including carbon, nitrogen, tin and lead.”
Joyce and colleagues believe the star is entering one of its last remaining pulses. They expect to see it expanding again “in our lifetimes”, before becoming a white dwarf within a few hundred thousand years.
“Both amateur and professional astronomers will continue to observe the evolution of the star in the coming decades, which will provide a direct test of our predictions within the next 30 to 50 years,” she says.
See the full article here .
See also ANU article here .
A stellar nursery at the heart of the Tarantula Nebula. (NASA, ESA, P Crowther/University of Sheffield)
ESO VLT at Cerro Paranal in the Atacama Desert, •ANTU (UT1; The Sun ), •KUEYEN (UT2; The Moon ), •MELIPAL (UT3; The Southern Cross ), and •YEPUN (UT4; Venus – as evening star). elevation 2,635 m (8,645 ft) from above Credit J.L. Dauvergne & G. Hüdepohl atacama photo
The most extreme of these stars was found in the cluster RMC 136a (or R136 as it is more usually named). Named R136a1, it is found to have a current mass of 265 times that of the Sun. Being a little over a million years old, R136a1 is already “middle-aged” and has undergone an intense weight-loss programme, shedding a fifth of its initial mass over that time, or more than fifty solar masses. It also has the highest luminosity, close to 10 million times greater than the Sun. R136 is a cluster of young, massive and hot stars located inside the Tarantula Nebula, in one of the neighbourhood galaxies of the Milky Way, the Large Magellanic Cloud, 165 000 light-years away.
Large Magellanic Cloud. Adrian Pingstone December 2003
R136 contains so many stars that on a scale equivalent to the distance between the Sun and the nearest star there are tens of thousands of stars. Hundreds of these stars are so incredibly bright that if we were to sit on a (hypothetical) planet in the middle of the cluster the sky would never get dark. This montage shows a visible-light image of the Tarantula nebula as seen with the Wide Field Imager on the MPG/ESO 2.2-metre telescope (left) along with a zoomed-in visible-light image from the Very Large Telescope (middle).
Wide Field Imager on the 2.2 Meter on the 2.2 meter MPG/ESO telescope at Cerro LaSilla Wide Field Imager on the 2.2 meter MPG/ESO telescope at Cerro LaSilla Wide Field Imager on the 2.2 meter MPG/ESO telescope at Cerro LaSillaMPG/ESO 2.2 meter telescope at Cerro La Silla, Chile, 600 km north of Santiago de Chile at an altitude of 2400 metresESO MAD on the VLT Unit 3
If life is to spark in the Universe like it does on Earth, a few things seem to be required, such as an atmosphere, ozone layer, liquid water, and habitable temperatures.
But before it ever gets to that point – before planets even form – space itself needs to be primed, courtesy of ultraviolet and optical light shining from massive, newly formed stars.
According to new research, this particular form of starlight provides a type of pressure that counteracts gravity, which slows down the rate of a galaxy’s star formation.
“If star formation happened rapidly, all stars would be bound together in massive clusters, where the intense radiation and supernova explosions would likely sterilise all the planetary systems, preventing the emergence of life,” explained astrophysicist Roland Crocker of the Australian National University.
“The conditions in these massive star clusters would possibly even prevent planets from forming in the first place.”
Gravity is vital to star formation. Most stars are born in stellar nurseries – dense molecular clouds in space that are rich with dust and gas. As interstellar winds and sometimes gravitational shockwaves ripple through, the material gets pushed into denser clumps, which then collapse under their own gravitational attraction.
These collapsed lumps continue to subsume surrounding material, rapidly growing in mass until nuclear fusion causes them to shine with light.
According to the paper by Crocker and his team, the very act of emitting starlight drives gas out of dense, isolated stellar protoclusters undergoing a furious rate of star formation, preventing them from further coalescing.
The ultraviolet and optical light from new massive stars scatters among the gas. The absorption of photons by the gas creates direct radiation pressure, whereas photons absorbed by the gas and re-emitted as infrared light create indirect radiation pressure.
Combined, the two types of radiation pressure can constitute a source of feedback – the process whereby star formation is quenched. This can also come from the powerful winds originating around an active supermassive black hole at a galaxy’s core.
“The phenomenon we studied occurs in galaxies and star clusters where there’s a lot of dusty gas that is forming heaps of stars relatively quickly,” Crocker said.
“In galaxies forming stars more slowly – such as the Milky Way – other processes are slowing things down. The Milky Way forms two new stars every year, on average.”
This is not a newly discovered process, but the mathematical modelling performed by Crocker and his team have put an upper limit on how quickly new stars can form. They found it takes significantly more than half the material in a molecular cloud to have been converted to stars for direct radiation pressure to push the remaining gas away.
“This and other forms of feedback help to keep the Universe alive and vibrant,” Crocker said.
ANU is a world-leading university in Australia’s capital city, Canberra. Our location points to our unique history, ties to the Australian Government and special standing as a resource for the Australian people.
Our focus on research as an asset, and an approach to education, ensures our graduates are in demand the world-over for their abilities to understand, and apply vision and creativity to addressing complex contemporary challenges.
For the first time, geologists have confirmed that our planet’s inner core is indeed solid – although not quite as firm as previous models have suggested.
Thanks to a new method for detecting soft whispers of seismic waves, analysis of an elusive type of earthquake ripple has revealed key properties of our planet’s deepest layer.
Researchers from the Australian National University (ANU) zeroed in on a low amplitude ‘J-phase’ seismic wave that passes through the planet’s core, allowing them to finally put constraints on its solidity.
As the planet’s crust grinds and groans on the surface, waves of energy are sent rippling their way through its gooey insides.
These come in various forms. Some, described as compressional waves, push back and forth through the planet’s body like a series of jittering train carriages. Others, called shear waves, surge up and down like the ocean’s surf along surfaces.
How one converts into the other according to various phase changes can tell you a lot about the properties of the material it’s passing through.
One particular variation called a J-phase should pass through the planet’s inner core, picking up details of the layer’s elasticity. That’s always been the theory, at least. The only problem is they’re rather quiet, making them virtually impossible to detect, so geologists have seen their measurement as something of a ‘Holy Grail’ of seismology.
Two ANU Earth scientists have now worked out a clever way to listen to these incredibly faint waves in the hum of earthquake vibrations echoing through our planet.
The method relies on taking any two seismic receivers on the planet’s surface and comparing notes several hours after the loudest rumbles have died away. With enough pairs of signals, a pattern can emerge.
“Using a global network of stations, we take every single receiver pair and every single large earthquake – that’s many combinations – and we measure the similarity between the seismograms,” says researcher Hrvoje Tkalčić.
“That’s called cross correlation, or the measure of similarity. From those similarities we construct a global correlogram – a sort of fingerprint of the Earth.”
A similar process was recently used [Journal of Geophysical Research:Solid Earth] to accurately measure the thickness of ice in Antarctica, providing a novel way to determine not just the properties of Earth’s layers, but potentially of other worlds as well.
Getting a grip on the nature of our planet’s guts is no easy task. We can barely dig more than 12 kilometres (about 7.5 miles) into the crust, which hardly scratches the surface, let alone reveals what’s thousands of kilometres underfoot.
A century ago, it was thought our planet had a thick crunchy outer coating and a gooey centre made of molten metals.
That all changed in the 1930s [American Museum of Natural History], following seismic readings of a large earthquake in New Zealand, which threw up signs of compression waves that shouldn’t have been there. A Danish seismologist by the name of Inge Lehmann suggested these patterns were most likely an echo bouncing off a solid centre.
This inner core has been firmly established in geological models of our planet’s structure. It’s about three quarters the size of our Moon, made of iron and nickel, and sizzles at a temperature roughly as hot as the Sun’s surface.
There might even be a complexity to its structure, with differences in how its iron crystals align giving the inner core its own ‘inner core’.
But even if all that is already established in geological models, it’s nice to now get firm evidence that scientists have been on the right track – besides, we got a bit of a surprise, too.
“We found the inner core is indeed solid, but we also found that it’s softer than previously thought,” says Tkalčić.
“It turns out – if our results are correct – the inner core shares some similar elastic properties with gold and platinum.”
All of this information is vital if we’re to build a firm understanding of phenomena like planetary formation, or how magnetic fields work.
Our own protective bubble of magnetism reverses regularly [PNAS], for example, and we still haven’t nailed down exactly how this happens.
“The understanding of the Earth’s inner core has direct consequences for the generation and maintenance of the geomagnetic field, and without that geomagnetic field there would be no life on the Earth’s surface,” says Tkalčić.
With a new way to listen to our planet’s rumbling, we’re almost certain to learn more about what its soft heart is telling us.
ANU is a world-leading university in Australia’s capital city, Canberra. Our location points to our unique history, ties to the Australian Government and special standing as a resource for the Australian people.
Our focus on research as an asset, and an approach to education, ensures our graduates are in demand the world-over for their abilities to understand, and apply vision and creativity to addressing complex contemporary challenges.
The new Gattini-IR telescope, now moving into full operation. Credit ANU-Caltech
Gattini-IR is a near-IR survey telescope newly-commissioned at Palomar Observatory in September 2018. Though it only has an aperture of 30 cm, it boasts a 25 sq deg field of view — 40 times larger than any other existing infrared telescope. Palomar Gattini-IR is designed to survey the entire accessible sky (20,000 sq deg) to 16.4 AB mag (J band) every night. We anticipate this facility will be a powerful tool for monitoring the variability of nearby brown dwarfs and asymptotic giant branch stars, detecting electromagnetic counterparts to gravitational wave detections, and discovering stellar mergers and Galactic novae. Gattini-IR is a pathfinder for more advanced systems to eventually be constructed at the polar sites of the South Pole, Antarctica and near Eureka on Ellesmere Island, Canada, which will enable observations out to K band. For more details see Moore et al. (2016)
Unveiling the dynamic infrared sky with Gattini-IR
While optical and radio transient surveys have enjoyed a renaissance over the past decade, the dynamic infrared sky remains virtually unexplored. The infrared is a powerful tool for probing transient events in dusty regions that have high optical extinction, and for detecting the coolest of stars that are bright only at these wavelengths. The fundamental roadblocks in studying the infrared time-domain have been the overwhelmingly bright sky background (250 times brighter than optical) and the narrow field-of-view of infrared cameras (largest is 0.6 sq deg). To begin to address these challenges and open a new observational window in the infrared, we present Palomar Gattini-IR: a 25 sq degree, 300mm aperture, infrared telescope at Palomar Observatory that surveys the entire accessible sky (20,000 sq deg) to a depth of 16.4 AB mag (J band, 1.25μm) every night. Palomar Gattini-IR is wider in area than every existing infrared camera by more than a factor of 40 and is able to survey large areas of sky multiple times. We anticipate the potential for otherwise infeasible discoveries, including, for example, the elusive electromagnetic counterparts to gravitational wave detections. With dedicated hardware in hand, and a F/1.44 telescope available commercially and cost-effectively, Palomar Gattini-IR will be on-sky in early 2017 and will survey the entire accessible sky every night for two years. We present an overview of the pathfinder Palomar Gattini-IR project, including the ambitious goal of sub-pixel imaging and ramifications of this goal on the opto-mechanical design and data reduction software. Palomar Gattini-IR will pave the way for a dual hemisphere, infrared-optimized, ultra-wide field high cadence machine called Turbo Gattini-IR. To take advantage of the low sky background at 2.5 μm, two identical systems will be located at the polar sites of the South Pole, Antarctica and near Eureka on Ellesmere Island, Canada. Turbo Gattini-IR will survey 15,000 sq. degrees to a depth of 20AB, the same depth of the VISTA VHS survey, every 2 hours with a survey efficiency of 97%.
The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”
Caltech campus
By studying the magnetic record left behind in earthly rocks, researchers found a magnetic field reversal – where magnetic north became magnetic south – lasting only 2 centuries.
Artist’s concept of Earth’s magnetic field, which surrounds and protects our planet, and which sometimes flips. Image via NASA/Peter Reid, University of Edinburgh/astrobio.net.
A research team led by scientists in Taiwan and China announced on August 21, 2018, that Earth’s protective magnetic field has undergone relatively rapid shifts in the past, including one lasting just two centuries.
Magnetosphere of Earth, original bitmap from NASA. SVG rendering by Aaron Kaase
That’s fast in contrast to the thousands of years thought to be needed for a magnetic pole reversal, an event whereby magnetic south becomes magnetic north and vice versa. Such an event might leave Earth with a substantially reduced magnetic field for some unknown period of time, exposing our world to dangerous effects from the sun. If it occurred in today’s world of ubiquitous electric power and global interconnected communications, a reduced magnetic field could cost us trillions of dollars. The peer-reviewed journal Proceedings of the National Academy of Sciences published this new work on August 20.
Co-author Andrew Roberts of Australian National University (ANU) said in a statement that Earth’s magnetic strength could decrease by about 90 percent during a magnetic reversal. He said:
“Earth’s magnetic field, which has existed for at least 3.45 billion years, provides a shield from the direct impact of solar radiation.
Even with Earth’s strong magnetic field today, we’re still susceptible to solar storms that can damage our electricity-based society.”
Roberts contributed to the study via precise magnetic analysis and radiometric dating of a stalagmite from a cave in southwestern China. Via this study, he and his colleagues added to the known paleomagnetic record from 107,000 to 91,000 years ago. A close look at this 16,000-year-long data set revealed that, during this period, the polarity flipped within only a couple of centuries some 98,000 years ago. Roberts commented:
“The record provides important insights into ancient magnetic field behavior, which has turned out to vary much more rapidly than previously thought.”
As the researchers described it, the flip was nearly 30 times faster than a generally accepted time required for polarity flips and 10 times faster than the fastest known rate of change.
Magnetic pole reversals are natural events, and earthly life has evolved for billions of years with them going on in the background. What’s different today is that humans have developed technologies susceptible to events on the sun. To give you an idea of how powerful the sun is, watch a bit of the video below, showing a July 19, 2012, eruption on the sun. The eruption produced a moderately powerful solar flare, exploding on the sun’s lower right hand limb, sending out light and radiation. It then produced a coronal mass ejection, or CME, which shot off to the right out into space. It’s the CMEs that are so dangerous to earthly technologies.
As do so many discussions of this kind, the ANU statement about the new work harked back to what’s called the Carrington Event of 1859. It’s named for the British astronomer Richard Carrington, who spotted the preceding solar flare. It’s the largest-ever solar super-storm on record (but, remember, our human record doesn’t last very long in contrast to the millions of years of human existence). According to an article in Physics World in 2014:
“This massive CME released … the equivalent to 10 billion Hiroshima bombs exploding at the same time. [It] hurled around a trillion kilograms [a million tons] of charged particles towards the Earth at speeds of up to 3,000 km/s [1900 miles/sec]. Its impact on the human population, though, was relatively benign as our electronic infrastructure at the time amounted to no more than about 200,000 kilometers [120,000 miles] of telegraph lines.”
The Carrington Event took place long before our vast electric power grids and satellites in orbit. A more recent event – the biggest earthly effect from a solar storm in living memory – happened on March 13, 1989. A storm on the sun that day caused auroras that could be seen as far south as Florida and Texas. It caused some satellites in orbit to lose control temporarily, and – most significantly – it sparked an electrical collapse of the Hydro-Québec power grid, causing a widespread electrical blackout for about nine hours.
And that is the issue. Events on the sun, and their accompanying CMEs, aren’t harmful to earthly life. After all, life on Earth has evolved for billions of years, as occasional solar super-storms took place. But these space weather events are harmful to human technologies, such as satellites and electrical grids.
Boom! A CME lifts off from the sun’s surface to space. This image was obtained in 2001 by the Solar and Heliospheric Observatory (SOHO) and is via ESA and NASA.
ESA/NASA SOHO ESA/NASA SOHO
For the most part, our magnetic field protects us. With Earth’s magnetic field in place, you would need an exceedingly strong solar flare to create a Carrington Event. But if Earth’s magnetic field were diminished due to an ongoing magnetic field reversal, our technologies would be left vulnerable. Roberts commented:
“Hopefully such an event is a long way in the future and we can develop future technologies to avoid huge damage, where possible, from such events.”
I think we can and will! What do you think?
Northern lights (aurora borealis) seen on Earth from orbit. The same events on the sun that cause these beautiful auroras have the potential to damage earthly electrical grids and satellites in orbit. Image via NASA/ESA.
Bottom line: Researchers have learned that magnetic field reversals on Earth can happen on a relatively fast timescale. They have evidence for one that took place over only two centuries. Prior to this work, it was thought that magnetic reversals took thousands of years.
ANU is a world-leading university in Australia’s capital city, Canberra. Our location points to our unique history, ties to the Australian Government and special standing as a resource for the Australian people.
Our focus on research as an asset, and an approach to education, ensures our graduates are in demand the world-over for their abilities to understand, and apply vision and creativity to addressing complex contemporary challenges.
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.
From July 1, the Australian National University (ANU), based in Canberra, will lead a conglomerate of 13 institutions to run the Anglo-Australian Telescope (AAT), located in Coonabarabran in the state of New South Wales.
AAO Anglo Australian Telescope near Siding Spring, New South Wales, Australia, Altitude 1,100 m (3,600 ft)
Australia’s largest optical telescope, the AAT has been operational for more than four decades. When it began operating, the 3.9 metre device was the first of its kind to map the southern hemisphere skies.
Housed at the picturesque Siding Spring Observatory, it has taken part in a multitude of missions that have added to humanity’s knowledge of the dark expanse out there.
These include one named Galactic Archaeology with Hermes (GALAH), which involved mapping hundreds of thousands of stars in the Milky Way. Another, the 2dF Galaxy Redshift Survey, measured changes in the light emitted by bodies in the northern and southern galactic hemispheres.
The current restructure allows the ANU to take over operation of the telescope from the Australian Astronomical Observatory.
This will allow Australian astronomers and universities to have unprecedented access to the highly sought-after advanced instruments, including a spectroscope capable of simultaneously observing 400 cosmic bodies. The move will also enable Australian scientists to access high-tech optic telescopes situated in Chile operated by the European Southern Observatory.
The academic partnerships will include universities from Victoria, New South Wales, Tasmania, Queensland and Western Australia.
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