Today in science: Albert Einstein and E=mc2

Albert Einstein, via rapgenius.com

September 27, 1905. On this date, while he was employed at a patent office, Albert Einstein published a paper titled Does the Inertia of a Body Depend Upon Its Energy-Content? It was the last of four papers he submitted that year to the journal Annalen der Physik. The first explained the photoelectric effect, the second offered experimental proof of the existence of atoms, and the third introduced the theory of special relativity. In the fourth paper, Einstein explained the relationship between energy and mass. That is, E=mc²

What does it mean? It means that, from the standpoint of physics, energy and mass are interchangeable. In the equation:

E is energy
m is mass
c is the speed of light

In other words, energy = mass X the speed of light squared.

It sounds simple, and its simplicity does belie the genius required of Einstein to express it so elegantly. Mass and energy are interchangeable. Plus, a small amount of mass can equal a large amount of energy; after all, the speed of light is a huge number (186,000 miles per second), and, in Einstein’s famous equation, that huge number is squared. So tiny mass can equal big energy.

E=mc² explains why the sun and other stars shine. In their interiors, atoms (mass) fuse together, creating the tremendous energy of the sun as described by Einstein’s famous equation.

Albert Einstein in 1905, his “miracle year.” Image via Wikimedia Commons

It’s also why, for example, scientists were able to learn how to build a single bomb that could wipe out a city, such as the world’s first deployed atomic bombs over the Japanese cities of Hiroshima and Nagasaki at the end of World War II.

These early atomic bombs worked due to nuclear fission, not fusion, but they worked on the principal that a tiny amount of mass could be converted to a large amount of energy, as described by Einstein.

Atomic bomb over Hiroshima (left) on August 6, 1945 and Nagasaki (right) on August 9, 1945. Read more about these images.

Interestingly, the equation E=mc² does not appear in Does the Inertia of a Body Depend Upon Its Energy-Content? That’s because Einstein used V to mean the speed of light in a vacuum and L to mean the energy lost by a body in the form of radiation.

E=mc² was not originally written as a formula but as a sentence in German that meant:

…if a body gives off the energy L in the form of radiation, its mass diminishes by L/V².

Einstein’s 1905 paper describing the interchangeable aspect of mass and energy was one of four papers he published during what’s now called his Annus mirabilis or miracle year.

These four articles forever changed our human perception of mass, energy, space and time.

Our sun, as seen with an x-ray telescope, showing the corona: the glowing million degree plasma that surrounds the sun. The sun’s energyis produced in its interior, via thermonuclear fusion. That is, mass is converted to energy in a way described by Albert Einstein’s famous equation, E=mc². Image via Yohkoh satellite.

Bottom line: On September 27, 1905, Albert Einstein published Does the Inertia of a Body Depend Upon Its Energy Content? in the journal Annalen der Physik. In it, he described the interchangeable nature of mass and energy, or E=mc².

from EarthSky https://ift.tt/2dzcjCC

Albert Einstein, via rapgenius.com

September 27, 1905. On this date, while he was employed at a patent office, Albert Einstein published a paper titled Does the Inertia of a Body Depend Upon Its Energy-Content? It was the last of four papers he submitted that year to the journal Annalen der Physik. The first explained the photoelectric effect, the second offered experimental proof of the existence of atoms, and the third introduced the theory of special relativity. In the fourth paper, Einstein explained the relationship between energy and mass. That is, E=mc²

What does it mean? It means that, from the standpoint of physics, energy and mass are interchangeable. In the equation:

E is energy
m is mass
c is the speed of light

In other words, energy = mass X the speed of light squared.

It sounds simple, and its simplicity does belie the genius required of Einstein to express it so elegantly. Mass and energy are interchangeable. Plus, a small amount of mass can equal a large amount of energy; after all, the speed of light is a huge number (186,000 miles per second), and, in Einstein’s famous equation, that huge number is squared. So tiny mass can equal big energy.

E=mc² explains why the sun and other stars shine. In their interiors, atoms (mass) fuse together, creating the tremendous energy of the sun as described by Einstein’s famous equation.

Albert Einstein in 1905, his “miracle year.” Image via Wikimedia Commons

It’s also why, for example, scientists were able to learn how to build a single bomb that could wipe out a city, such as the world’s first deployed atomic bombs over the Japanese cities of Hiroshima and Nagasaki at the end of World War II.

These early atomic bombs worked due to nuclear fission, not fusion, but they worked on the principal that a tiny amount of mass could be converted to a large amount of energy, as described by Einstein.

Atomic bomb over Hiroshima (left) on August 6, 1945 and Nagasaki (right) on August 9, 1945. Read more about these images.

Interestingly, the equation E=mc² does not appear in Does the Inertia of a Body Depend Upon Its Energy-Content? That’s because Einstein used V to mean the speed of light in a vacuum and L to mean the energy lost by a body in the form of radiation.

E=mc² was not originally written as a formula but as a sentence in German that meant:

…if a body gives off the energy L in the form of radiation, its mass diminishes by L/V².

Einstein’s 1905 paper describing the interchangeable aspect of mass and energy was one of four papers he published during what’s now called his Annus mirabilis or miracle year.

These four articles forever changed our human perception of mass, energy, space and time.

Our sun, as seen with an x-ray telescope, showing the corona: the glowing million degree plasma that surrounds the sun. The sun’s energyis produced in its interior, via thermonuclear fusion. That is, mass is converted to energy in a way described by Albert Einstein’s famous equation, E=mc². Image via Yohkoh satellite.

Bottom line: On September 27, 1905, Albert Einstein published Does the Inertia of a Body Depend Upon Its Energy Content? in the journal Annalen der Physik. In it, he described the interchangeable nature of mass and energy, or E=mc².

from EarthSky https://ift.tt/2dzcjCC

Science snaps: how nappy technology is helping us see cancer more clearly

This entry is part 22 of 22 in the series Science Snaps

The basics behind capturing an image haven’t changed in a long time. Home cameras and telescopes still use the same type of lenses, and microscopes in schools have been pretty much the same for decades.

This visible light technology is relatively cheap, but it’s limited by the laws of physics as to how much detail we can see. Scientists have found new ways to bend these rules with advanced technologies that see objects without using visible light. These include gamma ray telescopes and electron microscopes, but this technology comes with a price. And its own disadvantages.

What if we could find new ways to view images more clearly with the same cheap and easy-to-use equipment scientists have had for years? This is exactly where Professor Ed Boyden comes in.

The new concept

Boyden is a Professor in Neurotechnology at the Massachusetts Institute of Technology (MIT) in the US. Having already pioneered the use of light to control cells in the brain (optogenetics), he and his team gone on to make waves in microscopy too.

The team’s concept was a simple one. If we can’t improve microscopes to see smaller and smaller samples, why don’t we just make the samples bigger?

Theoretically, if scientists can make something larger, then the same laws of physics no longer apply. And this is exactly what he set out to do.

Boyden and his team were trying to separate the crowds of proteins in brain cells from one another, so they could be labelled better. They came up with the initial idea in 2007, but it wasn’t until 2012 when things started to click into place.

“Two great graduate students in my lab, Fei Chen and Paul Tillberg, were experimenting with nano-imaging,” he says. “But we realised it would be hard to apply these techniques to large, 3D specimens like those of the brain. So, we started thinking about how to do the opposite – to blow up the tissues!”

The challenge here was not only how to make the sample larger, but also to have it grow evenly in all three dimensions. It would be no use having the sample stretch in one direction like a rubber band, or non-uniformly like a popped corn kernel.

Boyden needed to expand his samples in a controlled way, so they looked the same, only bigger.

Expanding tissues using nappies

Surprisingly, the answer for this problem lay in the homes of parents around the world: babies’ nappies.

“We had been reading the papers of MIT physicist Toyoichi Tanaka,” Boyden says. “He had been working in the 1980s on the physics of swellable gels. And we thought maybe we could embed a piece of brain tissue into the same gels he’d been using.”

And that’s where they found their solution. It turned out that Tanaka’s gel was the perfect candidate for expanding microscopy samples. It’s also the chemical, or polymer, that’s responsible for absorbing babies’ pee in nappies. By just adding water, this chain-like polymer (called sodium polyacrylate) expands evenly in all directions and can swell to up to around a thousand times in volume.

All Boyden then had to do was find a way to embed this polymer within the tissue samples so that when it expands, the sample expands with it. And that meant fusing it to structures within the tissue. Boyden and his team found a way to “feed” cells the building blocks of the chains, which could then be joined together by triggering a chemical reaction.

After that, you simply add water.

The samples are then ready to be viewed using a standard light microscope, completing the process known as ‘expansion microscopy’.

 

The image above shows the ultrafine structures within kidney samples. The more detailed image, after expansion, allowed them to observe previously unseen processes.

The colours come from fluorescently labelled antibodies and small molecule DNA binders that glow under light or ultraviolet radiation.

Using expansion microscopy to tackle cancer

 

These images show Boyden’s first tests using expansion microscopy to look at cancers. The top image is a sample from a prostate cancer sample and the one below is from an ovarian cancer sample. The expanded images revealed features of filaments within cancer cells that are critical for their growth and spread, which couldn’t previously be seen with optical microscopes.  

Boyden is now applying this technology to look at cancer in more detail as part one of our Grand Challenge teams. He’s leading on the expansion microscopy work linked to Professor Greg Hannon’s project to create virtual reality maps of tumours.

“Imagine trying to understand human life but all you can see are the cities glowing on the earth’s surface from outer space,” says Boyden. “You can’t see people, or cars, or buildings. Would we really understand societies, economies, factories, transportation?”

According to Boyden, the same logic applies to cancer.

“The building blocks of life, genes and proteins, are nanoscale in dimension,” he says. “But by expanding cancers, we hope to map the fundamental building blocks of life.”

“Without doing that, how can we really understand what a cancer is?”

Boyden hopes that by seeing cancers with a resolution equal to the smallest building blocks of life, we’ll be able understand them at the most fundamental level, improving our ability to diagnose, treat and manage different cancers.

 

Carl Alexander is senior science media officer at Cancer Research UK

from Cancer Research UK – Science blog https://ift.tt/2xS6OqA

This entry is part 22 of 22 in the series Science Snaps

The basics behind capturing an image haven’t changed in a long time. Home cameras and telescopes still use the same type of lenses, and microscopes in schools have been pretty much the same for decades.

This visible light technology is relatively cheap, but it’s limited by the laws of physics as to how much detail we can see. Scientists have found new ways to bend these rules with advanced technologies that see objects without using visible light. These include gamma ray telescopes and electron microscopes, but this technology comes with a price. And its own disadvantages.

What if we could find new ways to view images more clearly with the same cheap and easy-to-use equipment scientists have had for years? This is exactly where Professor Ed Boyden comes in.

The new concept

Boyden is a Professor in Neurotechnology at the Massachusetts Institute of Technology (MIT) in the US. Having already pioneered the use of light to control cells in the brain (optogenetics), he and his team gone on to make waves in microscopy too.

The team’s concept was a simple one. If we can’t improve microscopes to see smaller and smaller samples, why don’t we just make the samples bigger?

Theoretically, if scientists can make something larger, then the same laws of physics no longer apply. And this is exactly what he set out to do.

Boyden and his team were trying to separate the crowds of proteins in brain cells from one another, so they could be labelled better. They came up with the initial idea in 2007, but it wasn’t until 2012 when things started to click into place.

“Two great graduate students in my lab, Fei Chen and Paul Tillberg, were experimenting with nano-imaging,” he says. “But we realised it would be hard to apply these techniques to large, 3D specimens like those of the brain. So, we started thinking about how to do the opposite – to blow up the tissues!”

The challenge here was not only how to make the sample larger, but also to have it grow evenly in all three dimensions. It would be no use having the sample stretch in one direction like a rubber band, or non-uniformly like a popped corn kernel.

Boyden needed to expand his samples in a controlled way, so they looked the same, only bigger.

Expanding tissues using nappies

Surprisingly, the answer for this problem lay in the homes of parents around the world: babies’ nappies.

“We had been reading the papers of MIT physicist Toyoichi Tanaka,” Boyden says. “He had been working in the 1980s on the physics of swellable gels. And we thought maybe we could embed a piece of brain tissue into the same gels he’d been using.”

And that’s where they found their solution. It turned out that Tanaka’s gel was the perfect candidate for expanding microscopy samples. It’s also the chemical, or polymer, that’s responsible for absorbing babies’ pee in nappies. By just adding water, this chain-like polymer (called sodium polyacrylate) expands evenly in all directions and can swell to up to around a thousand times in volume.

All Boyden then had to do was find a way to embed this polymer within the tissue samples so that when it expands, the sample expands with it. And that meant fusing it to structures within the tissue. Boyden and his team found a way to “feed” cells the building blocks of the chains, which could then be joined together by triggering a chemical reaction.

After that, you simply add water.

The samples are then ready to be viewed using a standard light microscope, completing the process known as ‘expansion microscopy’.

 

The image above shows the ultrafine structures within kidney samples. The more detailed image, after expansion, allowed them to observe previously unseen processes.

The colours come from fluorescently labelled antibodies and small molecule DNA binders that glow under light or ultraviolet radiation.

Using expansion microscopy to tackle cancer

 

These images show Boyden’s first tests using expansion microscopy to look at cancers. The top image is a sample from a prostate cancer sample and the one below is from an ovarian cancer sample. The expanded images revealed features of filaments within cancer cells that are critical for their growth and spread, which couldn’t previously be seen with optical microscopes.  

Boyden is now applying this technology to look at cancer in more detail as part one of our Grand Challenge teams. He’s leading on the expansion microscopy work linked to Professor Greg Hannon’s project to create virtual reality maps of tumours.

“Imagine trying to understand human life but all you can see are the cities glowing on the earth’s surface from outer space,” says Boyden. “You can’t see people, or cars, or buildings. Would we really understand societies, economies, factories, transportation?”

According to Boyden, the same logic applies to cancer.

“The building blocks of life, genes and proteins, are nanoscale in dimension,” he says. “But by expanding cancers, we hope to map the fundamental building blocks of life.”

“Without doing that, how can we really understand what a cancer is?”

Boyden hopes that by seeing cancers with a resolution equal to the smallest building blocks of life, we’ll be able understand them at the most fundamental level, improving our ability to diagnose, treat and manage different cancers.

 

Carl Alexander is senior science media officer at Cancer Research UK

from Cancer Research UK – Science blog https://ift.tt/2xS6OqA

Meet Fomalhaut, the loneliest star

Tonight, look for the lonelieststar. Which one is that? Many people would say the answer is Fomalhaut, a bright star in the constellation Piscis Austrinus the Southern Fish, bright enough to be seen on a moonlit night. Fomalhaut is a bright star – visible from all but far-northern latitudes – located in a region of the sky that contains only very faint stars. So it appears solitary in the night sky.

From the Northern Hemisphere, at about 8 to 9 p.m., look for a solitary star that’s peeking out at you just above the southeast horizon. See it? No other bright star sits so low in the southeast at this time of year. From this hemisphere, Fomalhaut dances close the southern horizon until well after midnight on these autumn nights. It reaches its highest point for the night in the southern sky at roughly 10:30 p.m. local time (11:30 p.m. daylight-saving time). At mid-northern latitudes, Fomalhaut sets in the southwest around 2 to 3 a.m. local time (3 to 4 a.m. local daylight-saving time).

From the Southern Hemisphere, Fomalhaut rises in a southeasterly direction, too, but this star climbs much higher up in the Southern Hemisphere sky and stays out for a longer period of time. Click here to find out precisely when Fomalhaut rises, transits (climbs highest up for the night) and sets in your sky.

Remember … it’s bright and solitary. The coming month or so presents a good time to see this star.

Fomalhaut is a bright white star, the brightest star in an otherwise empty-looking part of the sky. In skylore, you sometimes see it called the Lonely One, or the Solitary One, or sometimes the Autumn Star. Depending on whose list you believe, Fomalhaut is either the 17th or the 18th brightest star in the sky.

Roughly translated from Arabic, the star’s name means mouth of the fish or whale. Its constellation, Piscis Austrinus, represents the Southern Fish.

Besides being one of the brighter stars in the night sky, Fomalhaut has interest to professional astronomers. In 2008, it became the center of the first star with an extrasolar planet candidate (Fomalhaut b) imaged at visible wavelengths. The image was published in the journal Science in November, 2008. By the way, Fomalhaut is the third-brightest star (as viewed from Earth) known to have a planetary system, after the star Pollux in the constellation Gemini and our own sun.

View larger. | This image shows the debris ring around Fomalhaut and the location of its first known planet. This is the actual discovery image, published in the journal Science in November, 2008. Fomalhaut b was the first beyond our solar system visible to the eye in photographic images. Image via Hubble Space Telescope.

Bottom line: Go outside around mid-evening – and learn to keep company with Fomalhaut – brightest star in the constellation Piscis Austrinus, the Southern Fish – also called the loneliest star.

More about Fomalhaut here.

EarthSky’s guide to the bright planets

Donate: Your support means the world to us

from EarthSky https://ift.tt/1UUaLxz

Tonight, look for the lonelieststar. Which one is that? Many people would say the answer is Fomalhaut, a bright star in the constellation Piscis Austrinus the Southern Fish, bright enough to be seen on a moonlit night. Fomalhaut is a bright star – visible from all but far-northern latitudes – located in a region of the sky that contains only very faint stars. So it appears solitary in the night sky.

From the Northern Hemisphere, at about 8 to 9 p.m., look for a solitary star that’s peeking out at you just above the southeast horizon. See it? No other bright star sits so low in the southeast at this time of year. From this hemisphere, Fomalhaut dances close the southern horizon until well after midnight on these autumn nights. It reaches its highest point for the night in the southern sky at roughly 10:30 p.m. local time (11:30 p.m. daylight-saving time). At mid-northern latitudes, Fomalhaut sets in the southwest around 2 to 3 a.m. local time (3 to 4 a.m. local daylight-saving time).

From the Southern Hemisphere, Fomalhaut rises in a southeasterly direction, too, but this star climbs much higher up in the Southern Hemisphere sky and stays out for a longer period of time. Click here to find out precisely when Fomalhaut rises, transits (climbs highest up for the night) and sets in your sky.

Remember … it’s bright and solitary. The coming month or so presents a good time to see this star.

Fomalhaut is a bright white star, the brightest star in an otherwise empty-looking part of the sky. In skylore, you sometimes see it called the Lonely One, or the Solitary One, or sometimes the Autumn Star. Depending on whose list you believe, Fomalhaut is either the 17th or the 18th brightest star in the sky.

Roughly translated from Arabic, the star’s name means mouth of the fish or whale. Its constellation, Piscis Austrinus, represents the Southern Fish.

Besides being one of the brighter stars in the night sky, Fomalhaut has interest to professional astronomers. In 2008, it became the center of the first star with an extrasolar planet candidate (Fomalhaut b) imaged at visible wavelengths. The image was published in the journal Science in November, 2008. By the way, Fomalhaut is the third-brightest star (as viewed from Earth) known to have a planetary system, after the star Pollux in the constellation Gemini and our own sun.

View larger. | This image shows the debris ring around Fomalhaut and the location of its first known planet. This is the actual discovery image, published in the journal Science in November, 2008. Fomalhaut b was the first beyond our solar system visible to the eye in photographic images. Image via Hubble Space Telescope.

Bottom line: Go outside around mid-evening – and learn to keep company with Fomalhaut – brightest star in the constellation Piscis Austrinus, the Southern Fish – also called the loneliest star.

More about Fomalhaut here.

EarthSky’s guide to the bright planets

Donate: Your support means the world to us

from EarthSky https://ift.tt/1UUaLxz

Powerful jet from the wrong kind of star

Artist’s concept shows magnetic field lines around a neutron star (in white), a disk of material orbiting the neutron star and jets of material propelled outward. Image via ICRAR/Universiteit van Amsterdam.

It’s only been a few decades that jets have been part of the cosmic landscape. Astronomers see jets emanating various kinds of star systems, and from the area of both massive and supermassive black holes, but they are far from understanding them completely. On September 26, 2018, astronomers announced they used the Very Large Array (VLA) west of Socorro, New Mexico to discover a fast-moving jet of material propelled outward from a type of neutron star previously thought incapable of launching such a jet. The discovery, the scientists said, requires a fundamental revision in their ideas about how such jets originate.

Neutron stars are evolved stars – now superdense – what remains when a massive star explodes as a supernova. Jets from such stars occur in a commonly seen configuration of objects, where the very dense neutron star is paired with another star and pulls gravitationally on the other star. The material flowing from the other star forms a disk around the neutron star. Jets are seen perpendicular to the disk, propelled outward by some as yet not-understood mechanism at nearly the speed of light.

Jakob van den Eijnden of the University of Amsterdam is first author of the new study, which is published in the peer-reviewed journal Nature. He said:

We’ve seen jets coming from all types of neutron stars that are pulling material from their companions, with a single exception. Never before have we seen a jet coming from a neutron star with a very strong magnetic field.

That led to a theory that strong magnetic fields prevent jets from forming.

Now that theory may have to be revised.

Artist’s conception illustrates superdense neutron star, right, drawing material off its “normal” companion. Material forms an accretion disk rotating around the neutron star. Jets of material are launched perpendicular to the disk. Image via ICRAR/Universiteit van Amsterdam.

These scientists’ statement said they:

…studied an object called Swift J0243.6+6124 (Sw J0243), discovered on October 3, 2017, by NASA’s orbiting Neil Gehrels Swift Observatory, when the object emitted a burst of X-rays. The object is a slowly-spinning neutron star pulling material from a companion star that is likely significantly more massive than the sun.

The VLA observations began a week after the Swift discovery and continued until January 2018.

Both the fact that the object’s emission at X-ray and radio wavelengths weakened together over time and the characteristics of the radio emission itself convinced the astronomers that they were seeing radio waves produced by a jet.

Van den Eijnden said:

This combination is what we see in other jet-producing systems. Alternative mechanisms just don’t explain it.

Common theories for jet formation in systems like Sw J0243 say the jets are launched by magnetic field lines anchored in the inner parts of the accretion disks. In this scenario, if the neutron star has a very strong magnetic field, that field is overpowering and prevents the jet from forming. Van den Eijnden said:

Our clear discovery of a jet in Sw J0243 disproves that longstanding idea.

Or, there’s another possibility:

… the scientists suggest that Sw J0243’s jet-launching region of the accretion disk could be much farther out than in other types of systems, where the star’s magnetic field is weaker.

Another idea, they said, is that the jets may be powered by the neutron star’s rotation, instead of being launched by magnetic field lines in the inner accretion disk.

Nathalie Degenaar, also of the University of Amsterdam, said:

Interestingly, the rotation-powered idea predicts that the jet will be significantly weaker from more slowly rotating neutron stars, which is exactly what we see in Sw J0243.

The new discovery also implies that Sw J0243 may represent a large group of objects whose radio emission has been too weak to detect until new capabilities provided by the VLA’s major upgrade, completed in 2012, were available. If more such objects are found, the scientists said, they could test the idea that jets are produced by the neutron star’s spin.

The astronomers added that a jet from SwJ0243 may mean that another category of objects, called ultra-luminous X-ray pulsars, also highly magnetized, might produce jets. Degenaar said:

This discovery not only means we have to revise our ideas about jets from such systems, but also opens up exciting new areas of research.

Bottom line: Astronomers had theorized that strong magnetic fields prevent jets from forming. Then they studied an object called Swift J0243.6+6124 (Sw J0243) – a strongly magnetized neutron star – with a jet.

Via NRAO

Source: An evolving jet from a strongly magnetized accreting X-ray pulsar

from EarthSky https://ift.tt/2IimgRB

Artist’s concept shows magnetic field lines around a neutron star (in white), a disk of material orbiting the neutron star and jets of material propelled outward. Image via ICRAR/Universiteit van Amsterdam.

It’s only been a few decades that jets have been part of the cosmic landscape. Astronomers see jets emanating various kinds of star systems, and from the area of both massive and supermassive black holes, but they are far from understanding them completely. On September 26, 2018, astronomers announced they used the Very Large Array (VLA) west of Socorro, New Mexico to discover a fast-moving jet of material propelled outward from a type of neutron star previously thought incapable of launching such a jet. The discovery, the scientists said, requires a fundamental revision in their ideas about how such jets originate.

Neutron stars are evolved stars – now superdense – what remains when a massive star explodes as a supernova. Jets from such stars occur in a commonly seen configuration of objects, where the very dense neutron star is paired with another star and pulls gravitationally on the other star. The material flowing from the other star forms a disk around the neutron star. Jets are seen perpendicular to the disk, propelled outward by some as yet not-understood mechanism at nearly the speed of light.

Jakob van den Eijnden of the University of Amsterdam is first author of the new study, which is published in the peer-reviewed journal Nature. He said:

We’ve seen jets coming from all types of neutron stars that are pulling material from their companions, with a single exception. Never before have we seen a jet coming from a neutron star with a very strong magnetic field.

That led to a theory that strong magnetic fields prevent jets from forming.

Now that theory may have to be revised.

Artist’s conception illustrates superdense neutron star, right, drawing material off its “normal” companion. Material forms an accretion disk rotating around the neutron star. Jets of material are launched perpendicular to the disk. Image via ICRAR/Universiteit van Amsterdam.

These scientists’ statement said they:

…studied an object called Swift J0243.6+6124 (Sw J0243), discovered on October 3, 2017, by NASA’s orbiting Neil Gehrels Swift Observatory, when the object emitted a burst of X-rays. The object is a slowly-spinning neutron star pulling material from a companion star that is likely significantly more massive than the sun.

The VLA observations began a week after the Swift discovery and continued until January 2018.

Both the fact that the object’s emission at X-ray and radio wavelengths weakened together over time and the characteristics of the radio emission itself convinced the astronomers that they were seeing radio waves produced by a jet.

Van den Eijnden said:

This combination is what we see in other jet-producing systems. Alternative mechanisms just don’t explain it.

Common theories for jet formation in systems like Sw J0243 say the jets are launched by magnetic field lines anchored in the inner parts of the accretion disks. In this scenario, if the neutron star has a very strong magnetic field, that field is overpowering and prevents the jet from forming. Van den Eijnden said:

Our clear discovery of a jet in Sw J0243 disproves that longstanding idea.

Or, there’s another possibility:

… the scientists suggest that Sw J0243’s jet-launching region of the accretion disk could be much farther out than in other types of systems, where the star’s magnetic field is weaker.

Another idea, they said, is that the jets may be powered by the neutron star’s rotation, instead of being launched by magnetic field lines in the inner accretion disk.

Nathalie Degenaar, also of the University of Amsterdam, said:

Interestingly, the rotation-powered idea predicts that the jet will be significantly weaker from more slowly rotating neutron stars, which is exactly what we see in Sw J0243.

The new discovery also implies that Sw J0243 may represent a large group of objects whose radio emission has been too weak to detect until new capabilities provided by the VLA’s major upgrade, completed in 2012, were available. If more such objects are found, the scientists said, they could test the idea that jets are produced by the neutron star’s spin.

The astronomers added that a jet from SwJ0243 may mean that another category of objects, called ultra-luminous X-ray pulsars, also highly magnetized, might produce jets. Degenaar said:

This discovery not only means we have to revise our ideas about jets from such systems, but also opens up exciting new areas of research.

Bottom line: Astronomers had theorized that strong magnetic fields prevent jets from forming. Then they studied an object called Swift J0243.6+6124 (Sw J0243) – a strongly magnetized neutron star – with a jet.

Via NRAO

Source: An evolving jet from a strongly magnetized accreting X-ray pulsar

from EarthSky https://ift.tt/2IimgRB

Scientists spy roving dust storms on Titan

Artist’s concept of a dust storm on Titan. Image via ESA.

The only two worlds in our solar system, Earth and Mars, were known to have dust storms. Now a third world – a large moon of the giant planet Saturn – has been found to have dust storms, too. The data come from the long-lived and much-loved Cassini spacecraft, which orbited Saturn, weaving among its many moons, between 2004 and 2017. Cassini changed our view of Titan from a world shrouded in mystery (it has a very thick atmosphere) to one where Nature seems at once familiar and exotic. More about that below. The newly discovered dust storms appear to be huge. They appear to be moving in the region around Titan’s equator. The discovery is described in the September 24, 2018 edition of the peer-reviewed journal Nature Geoscience.

Sébastien Rodriguez, an astronomer at the University Paris Diderot, France, led the study and commented in a statement:

Titan is a very active moon.

We already know that about its geology and exotic hydrocarbon cycle [analogous to Earth’s water cycle]. Now we can add another analogy with Earth and Mars: the active dust cycle.

This animation is based on images captured by Cassini’s Visual and Infrared Mapping Spectrometer during several Titan flybys in 2009 and 2010. It shows clear bright spots appearing close to Titan’s equator around the time of its equinox, which scientists have interpreted as dust storms. The brightenings were visible for only a short period of time – between 11 hours to five Earth weeks – and cannot be seen in previous or subsequent images. Image via NASA/JPL-Caltech/University of Arizona/University Paris Diderot/IPGP/S. Rodriguez et al. 2018.

These scientists’ statement explained:

Titan is an intriguing world – in a way quite similar to Earth. In fact, it is the only moon of the solar system with a substantial atmosphere and the only celestial body other than our planet where stable bodies of surface liquid are known to still exist.

There is one big difference though: while on Earth such rivers, lakes and seas are filled with water, on Titan it is primarily methane and ethane that flows through these liquid reservoirs. In this unique methane cycle, the hydrocarbon molecules evaporate, condense into clouds and rain back onto the ground.

The weather on Titan varies from season to season, just as it does on Earth. In particular around the equinox, the time when the sun crosses Titan’s equator, massive clouds can form in tropical regions and cause powerful methane storms. Cassini observed such storms during several of its Titan flybys.

When Sébastien and his team first spotted three unusual equatorial brightenings in infrared images taken by Cassini around the moon’s 2009 northern equinox, they thought these might be exactly such methane clouds.

A thorough investigation revealed they were something completely different, however.

This compilation of images from nine Cassini flybys of Titan in 2009 and 2010 captures three instances when clear bright spots suddenly appeared in images taken by the spacecraft’s Visual and Infrared Mapping Spectrometer. The brightenings were only visible for a short period of time – between 11 hours to five Earth weeks – and cannot be seen in previous or subsequent images. Image via NASA/JPL-Caltech/University of Arizona/University Paris Diderot/IPGP/S. Rodriguez et al. 2018.

Sébastien Rodriguez commented:

From what we know about cloud formation on Titan, we can say that such methane clouds in this area and in this time of the year are not physically possible.

The convective methane clouds that can develop in this area and during this period of time would contain huge droplets and must be at a very high altitude, much higher than the 10 kilometers [6 miles] that modeling tells us the new features are located.

The researchers were also able to rule out that the features were on Titan’s surface, in the form of frozen methane rain or icy lavas. Such surface spots would have a different chemical signature and remain visible for much longer, these scientists said, while the bright features in this study were only visible for 11 hours to five weeks.

Computer modeling also showed that the features must be atmospheric, but still close to the surface – most likely forming a very thin layer of tiny solid organic particles. Since they were located right over the dune fields around Titan’s equator, the only remaining explanation was that the spots were actually clouds of dust raised from the dunes.

Sébastien Rodriguez said that – while this is the first-ever observation of a dust storm on Titan – the finding is not surprising:

We believe that the Huygens probe, which landed on the surface of Titan in January 2005, raised a small amount of organic dust upon arrival due to its powerful aerodynamic wake.

But what we spotted here with Cassini is at a much larger scale. The near-surface wind speeds required to raise such an amount of dust as we see in these dust storms would have to be very strong – about five times as strong as the average wind speeds estimated by the Huygens measurements near the surface and with climate models.

For the moment, the only satisfactory explanation for these strong surface winds is that they might be related to the powerful gusts that may arise in front of the huge methane storms we observe in that area and season.

This phenomenon, called ‘haboob’, can also be observed on Earth with giant dust clouds preceding storms in arid areas. See amazing pics and video from last summer’s haboobs in Arizona.

The existence of such strong winds generating massive dust storms also implies that the underlying sand can be set in motion, too, and that the giant dunes covering Titan’s equatorial regions are still active and continually changing.

The winds could be transporting the dust raised from the dunes across large distances, contributing to the global cycle of organic dust on Titan, and causing similar effects to those that can be observed on Earth and Mars.

The touchdown of ESA’s Huygens probe on Titan in January 2005 is relived in this animation. Via ESA / C. Carreau

Bottom line: Space scientists have evidence for dust storms moving across the surface of Titan, Saturn’s large moon. That makes Titan the third world in our solar system, along with Earth and Mars, known to have dust storms.

Source: Observational evidence for active dust storms on Titan at equinox

Via ESA

from EarthSky https://ift.tt/2DxZl5S

Artist’s concept of a dust storm on Titan. Image via ESA.

The only two worlds in our solar system, Earth and Mars, were known to have dust storms. Now a third world – a large moon of the giant planet Saturn – has been found to have dust storms, too. The data come from the long-lived and much-loved Cassini spacecraft, which orbited Saturn, weaving among its many moons, between 2004 and 2017. Cassini changed our view of Titan from a world shrouded in mystery (it has a very thick atmosphere) to one where Nature seems at once familiar and exotic. More about that below. The newly discovered dust storms appear to be huge. They appear to be moving in the region around Titan’s equator. The discovery is described in the September 24, 2018 edition of the peer-reviewed journal Nature Geoscience.

Sébastien Rodriguez, an astronomer at the University Paris Diderot, France, led the study and commented in a statement:

Titan is a very active moon.

We already know that about its geology and exotic hydrocarbon cycle [analogous to Earth’s water cycle]. Now we can add another analogy with Earth and Mars: the active dust cycle.

This animation is based on images captured by Cassini’s Visual and Infrared Mapping Spectrometer during several Titan flybys in 2009 and 2010. It shows clear bright spots appearing close to Titan’s equator around the time of its equinox, which scientists have interpreted as dust storms. The brightenings were visible for only a short period of time – between 11 hours to five Earth weeks – and cannot be seen in previous or subsequent images. Image via NASA/JPL-Caltech/University of Arizona/University Paris Diderot/IPGP/S. Rodriguez et al. 2018.

These scientists’ statement explained:

Titan is an intriguing world – in a way quite similar to Earth. In fact, it is the only moon of the solar system with a substantial atmosphere and the only celestial body other than our planet where stable bodies of surface liquid are known to still exist.

There is one big difference though: while on Earth such rivers, lakes and seas are filled with water, on Titan it is primarily methane and ethane that flows through these liquid reservoirs. In this unique methane cycle, the hydrocarbon molecules evaporate, condense into clouds and rain back onto the ground.

The weather on Titan varies from season to season, just as it does on Earth. In particular around the equinox, the time when the sun crosses Titan’s equator, massive clouds can form in tropical regions and cause powerful methane storms. Cassini observed such storms during several of its Titan flybys.

When Sébastien and his team first spotted three unusual equatorial brightenings in infrared images taken by Cassini around the moon’s 2009 northern equinox, they thought these might be exactly such methane clouds.

A thorough investigation revealed they were something completely different, however.

This compilation of images from nine Cassini flybys of Titan in 2009 and 2010 captures three instances when clear bright spots suddenly appeared in images taken by the spacecraft’s Visual and Infrared Mapping Spectrometer. The brightenings were only visible for a short period of time – between 11 hours to five Earth weeks – and cannot be seen in previous or subsequent images. Image via NASA/JPL-Caltech/University of Arizona/University Paris Diderot/IPGP/S. Rodriguez et al. 2018.

Sébastien Rodriguez commented:

From what we know about cloud formation on Titan, we can say that such methane clouds in this area and in this time of the year are not physically possible.

The convective methane clouds that can develop in this area and during this period of time would contain huge droplets and must be at a very high altitude, much higher than the 10 kilometers [6 miles] that modeling tells us the new features are located.

The researchers were also able to rule out that the features were on Titan’s surface, in the form of frozen methane rain or icy lavas. Such surface spots would have a different chemical signature and remain visible for much longer, these scientists said, while the bright features in this study were only visible for 11 hours to five weeks.

Computer modeling also showed that the features must be atmospheric, but still close to the surface – most likely forming a very thin layer of tiny solid organic particles. Since they were located right over the dune fields around Titan’s equator, the only remaining explanation was that the spots were actually clouds of dust raised from the dunes.

Sébastien Rodriguez said that – while this is the first-ever observation of a dust storm on Titan – the finding is not surprising:

We believe that the Huygens probe, which landed on the surface of Titan in January 2005, raised a small amount of organic dust upon arrival due to its powerful aerodynamic wake.

But what we spotted here with Cassini is at a much larger scale. The near-surface wind speeds required to raise such an amount of dust as we see in these dust storms would have to be very strong – about five times as strong as the average wind speeds estimated by the Huygens measurements near the surface and with climate models.

For the moment, the only satisfactory explanation for these strong surface winds is that they might be related to the powerful gusts that may arise in front of the huge methane storms we observe in that area and season.

This phenomenon, called ‘haboob’, can also be observed on Earth with giant dust clouds preceding storms in arid areas. See amazing pics and video from last summer’s haboobs in Arizona.

The existence of such strong winds generating massive dust storms also implies that the underlying sand can be set in motion, too, and that the giant dunes covering Titan’s equatorial regions are still active and continually changing.

The winds could be transporting the dust raised from the dunes across large distances, contributing to the global cycle of organic dust on Titan, and causing similar effects to those that can be observed on Earth and Mars.

The touchdown of ESA’s Huygens probe on Titan in January 2005 is relived in this animation. Via ESA / C. Carreau

Bottom line: Space scientists have evidence for dust storms moving across the surface of Titan, Saturn’s large moon. That makes Titan the third world in our solar system, along with Earth and Mars, known to have dust storms.

Source: Observational evidence for active dust storms on Titan at equinox

Via ESA

from EarthSky https://ift.tt/2DxZl5S

Opportunity emerges from Mars dust

View larger. | The HiRISE camera aboard NASA’s Mars Reconnaissance Orbiter (MRO) captured this image on September 20. The object centered in the square is the Opportunity rover, now visible again for the 1st time since a dust storm swept over it a little more than 100 days ago. Image via NASA/JPL-Caltech/Univ. of Arizona.

NASA said on September 25, 2018 that it still hasn’t heard from its Opportunity rover on Mars, which had been going strong on the Red Planet since landing there in early 2004. But, NASA announced:

… at least we can see it again.

A high-resolution camera (HiRISE) aboard NASA’s Mars Reconnaissance Orbiter captured a small object on the slopes of Mars’ Perseverance Valley. That object is Opportunity, which was descending into this valley on Mars when a dust storm swept over the region a little more than 100 days ago. NASA said:

The storm was one of several that stirred up enough dust to enshroud most of the Red Planet and block sunlight from reaching the surface. The lack of sunlight caused the solar-powered Opportunity to go into hibernation.

The rover’s team at NASA’s Jet Propulsion Laboratory in Pasadena, California, hasn’t heard from it since. On September 11, JPL began increasing the frequency of commands it beams to the 14-year-old rover.

The tau — a measurement of how much sunlight reaches the surface — over Opportunity was estimated to be a little higher than 10 during some points during the dust storm. The tau has steadily fallen in the last several months. On Thursday, September 20, when this image was taken, tau was estimated to be about 1.3 by MRO’s Mars Color Imager camera.

This image was produced from about 166 miles (267 km) above the Martian surface. The white box marks a 154-foot-wide (47-meter-wide) area centered on the rover.

Opportunity caught its own shadow on Mars on July 26, 2008. Read more about this image.

Bottom line: An image of the Opportunity rover on Mars, which has not been heard from since dust engulfed it in June, 2018. Updates on Opportunity can be found here.

Via NASA/JPL-Caltech.

from EarthSky https://ift.tt/2OfSfHk

View larger. | The HiRISE camera aboard NASA’s Mars Reconnaissance Orbiter (MRO) captured this image on September 20. The object centered in the square is the Opportunity rover, now visible again for the 1st time since a dust storm swept over it a little more than 100 days ago. Image via NASA/JPL-Caltech/Univ. of Arizona.

NASA said on September 25, 2018 that it still hasn’t heard from its Opportunity rover on Mars, which had been going strong on the Red Planet since landing there in early 2004. But, NASA announced:

… at least we can see it again.

A high-resolution camera (HiRISE) aboard NASA’s Mars Reconnaissance Orbiter captured a small object on the slopes of Mars’ Perseverance Valley. That object is Opportunity, which was descending into this valley on Mars when a dust storm swept over the region a little more than 100 days ago. NASA said:

The storm was one of several that stirred up enough dust to enshroud most of the Red Planet and block sunlight from reaching the surface. The lack of sunlight caused the solar-powered Opportunity to go into hibernation.

The rover’s team at NASA’s Jet Propulsion Laboratory in Pasadena, California, hasn’t heard from it since. On September 11, JPL began increasing the frequency of commands it beams to the 14-year-old rover.

The tau — a measurement of how much sunlight reaches the surface — over Opportunity was estimated to be a little higher than 10 during some points during the dust storm. The tau has steadily fallen in the last several months. On Thursday, September 20, when this image was taken, tau was estimated to be about 1.3 by MRO’s Mars Color Imager camera.

This image was produced from about 166 miles (267 km) above the Martian surface. The white box marks a 154-foot-wide (47-meter-wide) area centered on the rover.

Opportunity caught its own shadow on Mars on July 26, 2008. Read more about this image.

Bottom line: An image of the Opportunity rover on Mars, which has not been heard from since dust engulfed it in June, 2018. Updates on Opportunity can be found here.

Via NASA/JPL-Caltech.

from EarthSky https://ift.tt/2OfSfHk

Which one is ‘Oumuamua’s home star?

Artist’s concept of the object ‘Oumuamua. It traveled in the space between the stars to reach our solar system. Image via ESO/M. Kornmesser.

In late 2017, astronomers became aware of an interloper in our solar system, a small asteroid- or comet-like object from another star system. Interstellar objects had been expected, but this object – subsequently named ‘Oumuamua – was the first ever found. Over the past year, studies attempted to reconstruct ‘Oumuamua’s path and thereby learn its home solar system. But, until now, they hadn’t come up with plausible candidates. This week (September 25, 2018), that changed. A team of astronomers at the Max Planck Institute for Astronomy in Germany announced it has tracked ‘Oumuamua to several possible home systems. The team used data from ESA’s Gaia satellite to find four plausible stars where ‘Oumuamua could have begun its journey, more than a million years ago.

Coryn Bailer-Jones of Max Planck led the team that managed to back-track ‘Oumuamua’s motion and thereby to identify the four candidate stars. All four of them are dwarf stars, not surprising since dwarfs are the most common type of star in our Milky Way galaxy.

Various studies had already suggested that ‘Oumuamua was ejected from its home star’s planetary system during the planet formation phase, when there were many small-sized objects (planetesimals) flying around that interact with giant planets in the system.

The Max Planck team said ‘Oumuamua’s home star is likely to have two key properties. First, tracing back ‘Oumuamua’s orbit should lead directly back to, or at least very close to, the home star. Second, the relative speed of ‘Oumuamua and its home star is likely to be comparatively slow – objects are typically not ejected from their home systems at large speeds. A statement from Max Planck said:

The one that came closest to ‘Oumuamua, at least about one million year ago, is the reddish dwarf star HIP 3757. It approached within about 1.96 light-years. Given the uncertainties unaccounted for in this reconstruction, that is close enough for ‘Oumuamua to have originated from its planetary system (if the star has one). However, the comparatively large relative speed (around 25 km/s) makes it less probable for this to be ‘Oumuamua’s home.

The next candidate, HD 292249, is similar to our sun, was a little bit less close to the object’s trajectory 3.8 million years ago, but with a smaller relative speed of 10 km/s.

The two additional candidates met ‘Oumuamua 1.1 and 6.3 million years ago, respectively, at intermediate speeds and distances. These stars have been previously catalogued by other surveys, but little is known about them.

All four of these stars remain plausible candidates, these astronomers said, but they said:

… the smoking gun is still missing. In order to eject ‘Oumuamua at the observed speeds, the home system would have needed to feature a suitable giant planet that could slingshot ‘Oumuamua into the depths of space.

So far, no such planet has been detected around those stars – but since none of the stars have been examined closely for planets so far, that could well change in the future.

Read more from the Max Planck Institute of Astronomy

This chart wasn’t part of the study of ‘Oumuamua by Bailer-Jones et. al., but it gives you an idea of this object’s path through our solar system. Chart via Guy Ottewell’s blog.

Bottom line: A team of astronomers at the Max Planck Institute for Astronomy has identified four plausible candidates for ‘Oumuamua’s host star. ‘Oumuamua is the first object from interstellar space known to have passed through our solar system.

Source: Plausible home stars of the interstellar object ‘Oumuamua found in GaiaDR2

from EarthSky https://ift.tt/2xQlpmm

Artist’s concept of the object ‘Oumuamua. It traveled in the space between the stars to reach our solar system. Image via ESO/M. Kornmesser.

In late 2017, astronomers became aware of an interloper in our solar system, a small asteroid- or comet-like object from another star system. Interstellar objects had been expected, but this object – subsequently named ‘Oumuamua – was the first ever found. Over the past year, studies attempted to reconstruct ‘Oumuamua’s path and thereby learn its home solar system. But, until now, they hadn’t come up with plausible candidates. This week (September 25, 2018), that changed. A team of astronomers at the Max Planck Institute for Astronomy in Germany announced it has tracked ‘Oumuamua to several possible home systems. The team used data from ESA’s Gaia satellite to find four plausible stars where ‘Oumuamua could have begun its journey, more than a million years ago.

Coryn Bailer-Jones of Max Planck led the team that managed to back-track ‘Oumuamua’s motion and thereby to identify the four candidate stars. All four of them are dwarf stars, not surprising since dwarfs are the most common type of star in our Milky Way galaxy.

Various studies had already suggested that ‘Oumuamua was ejected from its home star’s planetary system during the planet formation phase, when there were many small-sized objects (planetesimals) flying around that interact with giant planets in the system.

The Max Planck team said ‘Oumuamua’s home star is likely to have two key properties. First, tracing back ‘Oumuamua’s orbit should lead directly back to, or at least very close to, the home star. Second, the relative speed of ‘Oumuamua and its home star is likely to be comparatively slow – objects are typically not ejected from their home systems at large speeds. A statement from Max Planck said:

The one that came closest to ‘Oumuamua, at least about one million year ago, is the reddish dwarf star HIP 3757. It approached within about 1.96 light-years. Given the uncertainties unaccounted for in this reconstruction, that is close enough for ‘Oumuamua to have originated from its planetary system (if the star has one). However, the comparatively large relative speed (around 25 km/s) makes it less probable for this to be ‘Oumuamua’s home.

The next candidate, HD 292249, is similar to our sun, was a little bit less close to the object’s trajectory 3.8 million years ago, but with a smaller relative speed of 10 km/s.

The two additional candidates met ‘Oumuamua 1.1 and 6.3 million years ago, respectively, at intermediate speeds and distances. These stars have been previously catalogued by other surveys, but little is known about them.

All four of these stars remain plausible candidates, these astronomers said, but they said:

… the smoking gun is still missing. In order to eject ‘Oumuamua at the observed speeds, the home system would have needed to feature a suitable giant planet that could slingshot ‘Oumuamua into the depths of space.

So far, no such planet has been detected around those stars – but since none of the stars have been examined closely for planets so far, that could well change in the future.

Read more from the Max Planck Institute of Astronomy

This chart wasn’t part of the study of ‘Oumuamua by Bailer-Jones et. al., but it gives you an idea of this object’s path through our solar system. Chart via Guy Ottewell’s blog.

Bottom line: A team of astronomers at the Max Planck Institute for Astronomy has identified four plausible candidates for ‘Oumuamua’s host star. ‘Oumuamua is the first object from interstellar space known to have passed through our solar system.

Source: Plausible home stars of the interstellar object ‘Oumuamua found in GaiaDR2

from EarthSky https://ift.tt/2xQlpmm