Astronomy Archives

June 23, 2011April 26, 2016 by Nancy Atkinson

Double Occultations This Week Will Reveal More Details About Pluto

Several teams of astronomers are taking advantage of a rare double event this week to learn more about the atmosphere and makeup of Pluto and its moons. The dwarf planet will occult, or pass in front of two different stars this week. One of the best viewing sites for these two events is in Hawaii, and eclipse-chaser Dr. Jay Pasachoff is there to record both events. “To see those occultations, we have to be in a particular set of places on Earth, those over which the shadow of the object in starlight passes,” Pasachoff wrote in a guest post on the Planet Hunters blog. “Since the stars are so far away, their light is essentially parallel and the shadows of the objects on Earth are the same as the sizes of the objects.”

If all goes well, we will know a lot more about the Pluto system, Pasachoff said.

Map of where the occultation would be visible on June 22-23, 2011.

Last night, June 22/23, both Pluto and its moon Charon occulted a magnitude 14.4 star, with each occultation lasting a minute or so and separated from each other by 12 minutes. “The event is particularly exciting because if we capture both Pluto and Charon nearly simultaneously, we can find out about the system’s internal orbits with higher precision than before, perhaps allowing a refinement of the center of mass and thus the masses and densities of each object,” Pasachoff said.

Also, the first deployment for an occultation of the NASA/German SOFIA observatory took place last night to view the Pluto occultation, flying at an altitude of 43,000 feet off the west coast of Central America.

“The scientific goal is to catch the ‘central flash,’ which conveys vital information about conditions in Pluto’s global atmosphere,” wrote American Astronomical Society press officer Rick Fienberg on Twitter. Fienberg was part of the press corps that was accompanying the flight.

On Sunday/Monday night, June 26/27, Pluto will occult a different star, and over a much narrower path, its small moon Hydra might also occult another star.

Pasachoff said that the most recent predictions for last night’s occulations shifted the prediction south, so that Hawaii is slightly off the main predicted path, to its north. But other teams are in Cairns, Australia, to see if it goes that far south.

For the June 26/27 event (June 27 UT but June 26 in Hawaii), the star is magnitude 13.6. “That is a couple of magnitudes brighter than most of the stars we have observed being occulted,” Pasachoff said, “so the data would be particularly low-noise. In addition to the occultation of Pluto itself, whose southern limit is predicted to pass through the Hawaiian islands, the tiny Pluto moon Hydra is to be occulted, though that narrow path’s prediction now passes north of the Hawaiian islands. We have arranged for telescopes in Yunnan, China, in Japan, Taiwan, and Thailand to observe with us, and MIT’s Matt Lockhart is en route to Yunnan with one of our POETS (Portable Occultation, Eclipse, and Transit System) cameras. We have Australian sites still observing as well, just in case the actual path is hundreds of kilometers south of the predictions.”

Earlier occultations by Pluto studied by Pasachoff and his colleagues showed that Pluto’s atmosphere was warming and that the atmosphere would probably remain warm enough by 2015 for the New Horizons spacecraft to detect and study it with its on-board instruments, and was part of the incentive for the mission to launch when it did.

To learn more about the occultations and the research, check out this main stellar occultation website from Williams College, where Pasachoff is located, which has links to the work of other researchers as well.

Maps and details of the predictions can be found here, and more details about Pluto occultations websites can be found here.

We’ll try to provide an update of the events when details become available.

You can follow Universe Today senior editor Nancy Atkinson on Twitter: @Nancy_A. Follow Universe Today for the latest space and astronomy news on Twitter @universetoday and on Facebook.

June 23, 2011January 18, 2016 by Ken Kremer

Packing a Mars Rover for the Trip to Florida

Check out this way cool time-lapse movie of NASA’s Curiosity Mars rover as its being packed up for her trip to Florida.

The video covers a 4 day period from June 13 to 17 and is condensed to just 1 minute. Watch the JPL engineers and technicians prepare Curiosity and the descent stage for shipping to the Kennedy Space Center in Florida and place it inside a large protective shipping container. Continue reading “Packing a Mars Rover for the Trip to Florida”

June 21, 2011December 24, 2015 by Jon Voisey

Slowing Down Stars

Forming Star's Magnetic Field Interacting With Disc Credit: NASA/JPL-Caltech/R. Hurt (SSC).

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One of the long standing challenges in stellar astronomy, is explaining why stars rotate so slowly. Given their large masses, as they collapsed to form, they should spin up to the point of flying apart, preventing them from ever reaching the point that they could ignite fusion. To explain this rotational braking, astronomers have invoked an interaction between the forming star’s magnetic field, and forming accretion disc. This interaction would slow the star allowing for further collapse to take place. This explanation is now over 40 years old, but how has it held up as it has aged?

One of the greatest challenges to testing this theory is for it to make predictions that are directly testable. Until very recently, astronomers were unable to directly observe circumstellar discs around newly formed stars. In order to get around this, astronomers have used statistical surveys, looking for the presence of these discs indirectly. Since dust discs will be warmed by the forming star, systems with these discs will have extra emission in the infrared portion of the spectra. According to the magnetic braking theory, young stars with discs should rotate more slowly than those without. This prediction was confirmed in 1993 by a team of astronomers led by Suzan Edwards at the University of Massachusetts, Amherst. Numerous other studies confirmed these general findings but added a further layer to the picture; stars are slowed by their discs to a period of ~8 days, but as the discs dissipate, the stars continue to collapse, spinning up to a period of 1-2 days.

Another interesting finding from these studies is that the effects seem to be most pronounced for stars of higher mass. When similar studies were conducted on young stars in the Orion and Eagle nebulae, researchers found that there was no sharp distinction between stars with or without disks for low mass stars. Findings such as these have caused astronomers to begin questioning how universal the magnetic disc braking is.

One of the other pieces of information with which astronomers could work was the realization around 1970 that there was a sharp divide in rotational speeds between high mass stars and lower mass ones at around the F spectral class. This phenomenon had been anticipated nearly a decade earlier when Evry Schatzman proposed that the stellar wind would interact with the star’s own magnetic field to create drag. Since these later spectral class stars tended to have more active magnetic fields, the braking effect would be more important for these stars.

Thus astronomers now had two effects which could serve to slow rotation rates of stars. Given the firm theoretical and observational evidence for each, they were both likely “right”, so the question became which was dominant in which circumstance. This question is one with which astronomers are still struggling.

To help answer the question, astronomers will need to gather a better understanding of how much each effect is at work in individual stars instead of simply large population surveys, but doing so is tricky. The main method employed to examine disc locking is to examine whether the inner edge of the disc is similar to the radius at which an object in a Keplarian orbit would have a similar angular velocity to the star. If so, it would imply that the star is fully locked with the disc’s inner edge. However, measuring these two values is easier said than done. To compare the values, astronomers must construct thousands of potential star/disc models against which to compare the observations.

In one recent paper astronomers used this technique on IC 348, a young open cluster. Their analysis showed that ~70% of stars were magnetically locked with the disc. However, the remaining 30% were suspected to have inner disc radii beyond the reach of the magnetic field and thus, unavailable for disc braking. However, these results are somewhat ambiguous. While the strong number of stars tied to their discs does support the disc braking as an important component of the rotational evolution of the stars, it does not distinguish whether it is presently a dominant feature. As previously stated, many of the stars could be in the process of evaporating the discs, allowing the star to again spin-up. It is also not clear if the 30% of stars without evidence of disc locking were locked in the past.

Research like this is only one piece to a larger puzzle. Although the details of it aren’t fully fleshed out, it is readily apparent that these magnetic braking effects, both with discs and stellar winds, play a significant effect on slowing the angular speed of stars. This runs completely contrary to the frequent Creationist claim that “[t]here is no know [sic] mechanical process which could accomplinsh [sic] this transfer of momentum”.

June 20, 2011December 24, 2015 by VirtualAstro

The longest day – Summer Solstice 21st June 2011

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June 21st, 2011 is Summer Solstice – the longest day of the year.

This is the time when the Sun is at its highest or most northerly point in the sky in the Northern Hemisphere and when we receive the most hours of daylight. If you live in the Southern Hemisphere it is the reverse, so you will be having “Winter Solstice.”

Also known as “Midsummer” the Summer Solstice gets its name from the Latin for sol (sun) and sistere (to stand still). The Sun reaches its most Northerly point and momentarily stands still before starting its journey South in the sky again until it reaches its most Southerly point “Winter Solstice”, before repeating the cycle. This is basically how we get our seasons.

It’s not actually the Sun that moves North or South over the seasons although it may appear so. It’s the Earths axial tilt that causes the Sun to change position in the sky as the Earth orbits the Sun throughout the year.

Why Are There Seasons — The angle of the Sun and the Earth's seasons. Image credit: NASA

Summer Solstice/ Midsummer is steeped in ancient folklore especially in Northern Europe with the most famous place directly related to it being Stonehenge, where the sun has been worshiped for thousands of years.

The Sun reaches its most Northerly point in the sky at 17:16 UTC momentarily and from that point forward starts to make its way South. This means the days will get shorter and shorter until Winter Solstice in December.

June 15, 2011December 24, 2015 by Jon Voisey

How Much Do Binary Stars Shape Planetary Nebulae?

A Collectionf of Planetary Nebulae from the HST

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Planetary nebulae come in a dazzling array of shapes, from spherical shells of gas, to blobby structures barely containing symmetry at all. Controversy has surrounded the cause for this diversity. Could it be magnetic fields, high rotation rates, unseen companions, or something else entirely? Recently, there has been a growing consensus that binary companions are the main culprit for the most irregular of these nebulae, but exploring the connection is only possible with a statistically significant sample of planetary nebulae with binary cores can be found, giving hints as to what properties they may, or may not, create.

Currently, astronomers recognize over 3,000 planetary nebulae within our own galaxy. Only ~40 are known to harbor binary stars at their core but astronomers are uncertain of just how many truly due. The difficulty lies in the amount of time it takes to search for a companion. Typically, companions can be discovered with spectroscopic measurements in the same way astronomers discover planets by detecting a wobble. Alternatively, binary companions can be teased out through eclipses but both methods require frequent monitoring and, until recently, were best suited for single target studies.

With the recent popularity of wide field survey missions, possibilities to detect more binary companions has increased greatly. These surveys are ideally suited for capturing eclipses or microlensing events. In each case, they will preferentially discover companions with tight orbits and short orbital periods which are suspected to have the greatest effect on the shape of the nebulae.

Stars that orbit close together are expected to have a strong effect because, as the primary star enters its post-main sequence lifetime, it is likely that the secondary star will become engulfed in the envelope of the primary, essentially sharing the outer layers. This creates large differences in density along the equator which leads to uneven ejection of the material as the primary star sheds its outer layers, forming the nebula. These temporary overdensities would serve to funnel material and could be responsible for the presence of polar outflows or jets.

A recent study has added two more planetary nebulae to the list of those with known binary centers: NGC 6326 (shown right) and NGC 6778. Collimated outflows and jets were discovered in both cases. The authors also note that both nebulae have filaments with low ionization. Such structures have been noted previously, but their cause has remained uncertain. A 2009 study suggested that they may be the result of tight binaries, a hypothesis that is strengthened by the the new discovery. The overall shape of NGC 6326 is mostly elliptical while NGC 6778 is bipolar.

June 14, 2011December 24, 2015 by Tammy Plotner

Stellar Super Soaker

A star is born: Swirling gas and dust fall inward, spurring polar jets, shown in blue in this illustration. Illustration courtesy NASA/Caltech

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Located in the constellation of Perseus and just a mere 750 light years from Earth, a young protostar is very busy spewing forth copious amounts of water. Embedded in a cloud of gas and dust, the hundred thousand year old infant is blasting out this elemental life ingredient from both poles like an open hydrant – and its fast moving droplets may be seeding our Universe…

“If we picture these jets as giant hoses and the water droplets as bullets, the amount shooting out equals a hundred million times the water flowing through the Amazon River every second,” said Lars Kristensen, a postdoctoral astronomer at Leiden University in the Netherlands and lead author of the new study detailing the discovery, which has been accepted for publication in the journal Astronomy & Astrophysics.. “We are talking about velocities reaching 200,000 kilometers [124,000 miles] per hour, which is about 80 times faster than bullets flying out of a machine gun.”

To capture the the quicksilver signature of hydrogen and oxygen atoms, the researchers employed the infrared instruments on-board the European Space Agency’s Herschel Space Observatory. Once the atoms were located, they were followed back to the star where they were formed at just a few thousand degrees Celsius. But like hitting hot black top, once the droplets encounter the outpouring of 180,000-degree-Fahrenheit (100,000-degree-Celsius) gas jets, they turn into a gaseous format. “Once the hot gases hit the much cooler surrounding material – at about 5,000 times the distance from the sun to Earth – they decelerate, creating a shock front where the gases cool down rapidly, condense, and reform as water.” Kristensen said.

Like kids of all ages playing with squirt guns, this exciting discovery would appear to be a normal part of a star “growing up” – and may very well have been part of our own Sun’s distant past. “We are only now beginning to understand that sun-like stars probably all undergo a very energetic phase when they are young,” Kristensen said. “It’s at this point in their lives when they spew out a lot of high-velocity material – part of which we now know is water.”

Just like filling summer days with fun, this “star water” may well be enhancing the interstellar medium with life-giving fundamentals… even if that “life” is the birth of another star. The water-jet phenomenon seen in Perseus is “probably a short-lived phase all protostars go through,” Kristensen said. “But if we have enough of these sprinklers going off throughout the galaxy – this starts to become interesting on many levels.”

Skip the towel. I’ll let the Sun dry me off.

Original Story Source: National Geographic.

June 13, 2011December 24, 2015 by Jon Voisey

Measuring Fundamental Constants with Methanol

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Key to the astronomical modeling process by which scientists attempt to understand our universe, is a comprehensive knowledge of the values making up these models. These are generally measured to exceptionally high confidence levels in laboratories. Astronomers then assume these constants are just that – constant. This generally seems to be a good assumption since models often produce mostly accurate pictures of our universe. But just to be sure, astronomers like to make sure these constants haven’t varied across space or time. Making sure, however, is a difficult challenge. Fortunately, a recent paper has suggested that we may be able to explore the fundamental masses of protons and electrons (or at least their ratio) by looking at the relatively common molecule of methanol.

The new report is based on the complex spectra of the methane molecule. In simple atoms, photons are generated from transitions between atomic orbitals since they have no other way to store and translate energy. But with molecules, the chemical bonds between the component atoms can store the energy in vibrational modes in much the same way masses connected to springs can vibrate. Additionally, molecules lack radial symmetry and can store energy by rotation. For this reason, the spectra of cool stars show far more absorption lines than hot ones since the cooler temperatures allow molecules to begin forming.

Many of these spectral features are present in the microwave portion of the spectra and some are extremely dependent on quantum mechanical effects which in turn depend on precise masses of the proton and electron. If those masses were to change, the position of some spectral lines would change as well. By comparing these variations to their expected positions, astronomers can gain valuable insights to how these fundamental values may change.

The primary difficulty is that, in the grand scheme of things, methanol (CH₃OH) is rare since our universe is 98% hydrogen and helium. The last 2% is composed of every other element (with oxygen and carbon being the next most common). Thus, methanol is comprised of three of the four most common elements, but they have to find each other, to form the molecule in question. On top of that, they must also exist in the right temperature range; too hot and the molecule is broken apart; too cold and there’s not enough energy to cause emission for us to detect it. Due to the rarity of molecules with these conditions, you might expect that finding enough of it, especially across the galaxy or universe, would be challenging.

Fortunately, methanol is one of the few molecules which are prone to creating astronomical masers. Masers are the microwave equivalent of lasers in which a small input of light can cause a cascading effect in which it induces the molecules it strikes to also emit light at specific frequencies. This can greatly enhance the brightness of a cloud containing methanol, increasing the distance to which it could be readily detected.

By studying methanol masers within the Milky Way using this technique, the authors found that, if the ratio of the mass of an electron to that of a proton does change, it does so by less than three parts in one hundred million. Similar studies have also been conducted using ammonia as the tracer molecule (which can also form masers) and have come to similar conclusions.

June 13, 2011December 24, 2015 by Tammy Plotner

Carbon Monoxide Reveals Distant Milky Way Arm

The Milky Way's basic structure is believed to involve two main spiral arms emanating from opposite ends of an elongated central bar. But only parts of the arms can be seen - gray segments indicate portions not yet detected. Other known spiral arm segments--including the Sun's own spur--are omitted for clarity. Credit: T. Dame

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Our Milky Way Galaxy’s elemental form is hypothesized to be a barred structure – made up of two major spiral arms originating at both poles of the central bar. But from our vantage point, we can only see portions of those arms. Because of huge amounts of dust literally blocking our view, we can’t be as confident of our structure as other galaxies we can study as a whole. However, by “sniffing our galaxy’s tailpipe”, we’re able to judge our structure just a little bit better.

We’re all aware of theoretical models of the Milky Way… a sprawling, pinwheel-like structure with sweeping, grandiose arms loaded with stars, gases and dust. We’re also aware our Solar System is lodged in a spur of those arms, slowly orbiting and located about 25,000 light-years from the center. But hard and fast details of our Galaxy haven’t been possible until now. Thanks to the use of radio waves, we’re able to cut through the murk and see wavelengths that give us clues. These architectural hints are coming to us in the forms of molecules like carbon monoxide – a great tracer of our galactic format.

Using a small 1.2-meter radio telescope on the roof of their science building in Cambridge, CfA astronomers Tom Dame and Pat Thaddeus used carbon monoxide emissions to ferret out proof there is more spiral structure located in the most distant parts of our galactic home. What they uncovered was a previously reported new spiral arm at the far end of the Scutum-Centaurus Arm – but how they did it was by verifying vast, dense concentrations of this molecular gas.

Where does it come from? Try the “exhaust” of carbon stars. These late-type stars have an atmosphere which is higher in carbon than oxygen. When the two combine in the upper layers of the star they create carbon monoxide. It also happens in “normal” stars like our Sun, too. It’s richer in oxygen than carbon, but still cool enough to form carbon monoxide. “After preliminary Galactic surveys in the mid-1970’s revealed the vast extent of CO emission on the sky,” says Dame, “It became clear that even with the relatively large beams of the 1.2 meter telescopes a sensitive, well-sampled survey of the entire Galaxy would require many years.”

And its time has come…

Original Story Source: Smithsonian Astrophysical Observatory.

June 12, 2011December 24, 2015 by Jon Voisey

What’s up with Iapetus?

The dark and light side of Iapetus. Credit: NASA/JPL/Space Science Institute

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Although Saturn’s moon Iapetus was first discovered in 1671 by Giovanni Cassini, its behavior was extremely odd. Cassini was able to regularly find the moon when it was to the west of Saturn, but when he waited for it to swing around to Saturn’s east side, it seemed to vanish. It wasn’t until 1705 that Cassini finally observed Iapetus on the eastern side, but it took a better telescope because the side Iapetus presented when to the east was a full two magnitudes darker. Cassini surmised that this was due to a light hemisphere, presented when Iapetus was to the west, and a dark one, visible when it was to the east due to tidal locking.

With the advances in telescopes, the reason for this dark divide has been the subject of much research. The first explanations came in the 1970’s and a recent paper summarizes the work done so far on this fascinating satellite as well as expanding it to the larger context of some of Saturn’s other moons.

The foundation for the current model of Iapetus’ uneven display was first proposed by Steven Soter, one of the co-writers for Carl Sagans Cosmos series. During a colloquium of the International Astronomical Union, Soter proposed that micrometeorite bombardment of another of Saturn’s moons, Pheobe, drifted inwards and were picked up by Iapetus. Since Iapetus keeps one side facing Saturn at all times, this would similarly give it a leading edge that would preferentially pick up the dust particles. One of the great successes of this theory is that the center of the dark region, known as the Cassini Regio, is directly situated along the path of motion. Additionally, in 2009, astronomers discovered a new ring around Saturn, following Phoebe’s retrograde orbit, although slightly interior to the moon, adding to the suspicion that the dust particles should drift inwards, due to the Poynting-Robertson effect.

In 2010, a team of astronomers reviewing the images from the Cassini mission, noted that the coloration had properties that didn’t quite fit with Soter’s theory. If deposition from dust was the end of the story, it was expected that the transition between the dark region and the light would be very gradual as the angle at which they would strike the surface would become elongated, spreading out the incoming dust. However, the Cassini mission revealed the transitions were unexpectedly abrupt. Additionally, Iapetus’ poles were bright as well and if dust accumulation was as simple as Soter had suggested, they should be somewhat coated as well. Furthermore, spectral imaging of the Cassini Regio revealed that its spectrum was notably different than that of Phoebe. Another potential problem was that the dark surface extended past the leading side by more than ten degrees.

Revised explanations were readily forthcoming. The Cassini team suggested that the abrupt transition was due to a runaway heating effect. As the dark dust accumulated, it would absorb more light, converting it to heat and helped to sublimate more of the bright ice. In turn, this would reduce the overall brightness, again increasing the heating, and so on. Since this effect amplified the coloration, it could explain the more abrupt transition in much the same way as adjusting the contrast on an image will sharpen gradual transitions between colors. This explanation also predicted that the sublimated ice could travel around the far side of the moon, freezing out and enhancing the brightness on the other sides as well as the poles.

To explain the spectral differences, astronomers proposed that Phoebe may not be the only contributor. Within Saturn’s satellite system, there are over three dozen irregular satellites with dark surfaces which could also potentially contribute, altering the chemical makeup. But while this sounded like a tantalizingly straight-forward solution, confirmation would require further investigation. The new study, led by Daniel Tamayo at Cornell University, analyzed the efficiency with which various other moons could produce dust as well as the likelihood with which Iapetus could scoop it up. Interestingly, their results showed that Ymir, a mere 18 km in diameter, “should be roughly as important a contributor of dust to Iapetus as Phoebe”. Although none of the other moons, independently looked to be as strong of sources for dust, the sum of dust coming the remaining irregular, dark moons was found to be at least as important as either Ymir or Phoebe. As such, this explanation for the spectral deviation is well grounded.

The last difficulty, that of spreading dust past the leading face of the moon, is also explained in the new paper. The team proposes that eccentricities in the orbit of the dust allow it to strike the moon at odd angles, off from the leading hemisphere. Such eccentricities could be readily produced by solar radiation, even if the orbit of the originating body was not eccentric. The team carefully analyzed such effects and produced models capable of matching the dust distribution past the leading edge.

The combination of these revisions seem to secure Soter’s basic premise. A further test would be to see if other large satellites like Iapetus also showed signs of dust deposition, even if not so starkly divided since most other moons lack the synchronous orbit. Indeed, the moon Hyperion was found to have darker regions pooling in its craters when Cassini few by in 2007. These dark regions also revealed similar spectra to that of Cassini Regio. Saturn’s largest moon, Titan is also tidally locked and would be expected to sweep up particles on its leading edge, but due to its thick atmosphere, the dust would likely be spread moon-wide. Although difficult to confirm, some studies have suggested that such dust may help contribute to the haze Titan’s atmosphere exhibits.

June 9, 2011December 24, 2015 by Tammy Plotner

Mathematics Explain Dynamics of Superfluid

A 2001 photo from the space shuttle shows a phenomenon called von Karman vortices in clouds downwind from Rashiri Island in the northern Sea of Japan. The vortices are similar to those that form in superfluids. Credit: NASA

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At nearly the coldest temperature possible – mercury (with the aid of liquid helium) – forms a state called superconductivity. At the extreme, electrons flow unencumbered through what is known as a superfluid. But the hows and whys of superfluid behavior defied explanation. Until now…

When taken to within a few degrees of absolute zero on the Kelvin scale (minus 273 Celsius or minus 460 Fahrenheit), liquid helium-4 turns into the remarkable superfluid state. It swirls, it curls, and it’s lack of body has been baffling scientists for nearly a century. Now a team led by a University of Washington physicist, using the most powerful supercomputer available for open science, has cooked up a theoretical picture which explains the real-time behavior of superfluid. Just who is the responsible party here? Try subatomic particles called fermions.

Femions are a much a part of the natural equation as electrons, protons and neutrons… just as superfluids are part of neutron stars. Rotating between one and 1,000 times a second, neutron stars – or pulsars – superfluid surface acts much differently than its counterpart here on Earth. As the speed increases, it forms a series of small vortices which group in a triangular pattern… which in turn forms a braid within the superfluid structure. “When you reach the correct speed, you’ll create one vortex in the middle,” Bulgac said. “And as you increase the speed, you will increase the number of vortices. But it always occurs in steps.”

Can science recreate it? Yes. Laboratory models utilizing a vacuum chamber and a laser beam to create a high-intensity electrical field have managed to chill a small sample, perhaps 1 million atoms, to temperatures near absolute zero. Then a “laser spoon” is employed to stir the superfluid fast enough to create vortices.

“In trying to understand the odd behavior, scientists have attempted to devise descriptive equations, such as ones they might use to describe the swirling action in a cup of coffee as it is stirred.” Bulgac said. “But to describe the action in a superfluid made of fermions, a nearly limitless number of equations is needed. Each describes what happens if just one variable – such as velocity, temperature or density – is changed. Because the variables are linked, if one changes others will change as well.”

One of the major challenges in formulating a mathematical hypothesis is the amount of computing power it would take to work through a problem with a number of variable changes that reached 1 trillion or more. So how did they do it? The team used the JaguarPF computer at Oak Ridge National Laboratory in Tennessee, one of the largest supercomputers in the world, for the equivalent of 70 million hours, which would require almost 8,000 years on a single-core personal computer (JaguarPF has nearly a quarter-million cores). Just try to cool that!

“This tells you the complexity of these calculations and how difficult this is,” Bulgac said. To make matters even more complex, the faster the superfluid is stirred causes it to lose its properties – but not as fast as hypothesized. “The work means that researchers can ‘to some extent’ study the properties of a neutron star using computer simulations.” Bulgac said. .”It also opens new directions of research in cold-atom physics.”

And more homework on our part.

Original Story Source: University of Washington.