Supercomputer Simulation of Magnetic Field Loops on the Sun

Magnetic fields emerging from below the surface of the sun influence the solar wind, a stream of particles that blows continuously from the sun’s atmosphere through the solar system. 

Researchers at NASA and its university partners are using high-fidelity computer simulations to learn how these magnetic fields emerge, heat the sun’s outer atmosphere and produce sunspots and flares.

This visualization shows magnetic field loops in a portion of the sun, with colors representing magnetic field strength from weak (blue) to strong (red). 

The simulation was run on the Pleiades supercomputer at the NASA Advanced Supercomputing facility at NASA's Ames Research Center in Moffett Field, California. 

The knowledge gained through simulation results like this one help researchers better understand the sun, its variations, and its interactions with Earth and the solar system.

Image Credit: Robert Stein, Michigan State University; Timothy Sandstrom, NASA/Ames

The sun has gone quiet: Sunspots and CME

The Sun by the Atmospheric Imaging Assembly of NASA's Solar Dynamics Observatory. 

Credit: NASA

The sun has gone quiet. Almost too quiet.

A few weeks ago it was teeming with sunspots, as you would expect since we are supposed to be in the middle of solar maximum-the time in the sun's 11-year cycle when it is the most active but now, there is hardly a sunspot in sight.

In an image taken Friday by NASA's Solar Dynamics Observatory, there is a tiny smidgen of brown just right of center where a small sunspot appears to be developing. But just one day before, there was nothing. It was a totally spotless day.

So what's going on here? Is the "All Quiet Event" as solar physicist Tony Phillips dubbed it, a big deal, or not?

"It is weird, but it's not super weird," said Phillips, who writes about solar activity on his web site SpaceWeather.com.

"To have a spotless day during solar maximum is odd, but then again, this solar maximum we are in has been very wimpy."

Phillips notes that this is the weakest solar maximum to have been observed in the space age, and it is shaking out to be the weakest one in the past 100 years, so the spotless day was not so totally out of left field.

"It all underlines that solar physicists really don't know what the heck is happening on the sun," Phillips said.

"We just don't know how to predict the sun, that is the take away message of this event."

Sunspots are interesting to solar observers because they are the region of the sun where solar activity such as solar flares (giant flashes of light) and coronal mass ejections (when material from the sun goes shooting off into space) originate.

They are caused by highly concentrated magnetic fields that are slightly cooler than the surrounding surface of the sun, which is why they appear dark to us.

Those intense magnetic fields can get twisted up and tangled, which causes a lot of energy to build up. Solar flares and coronal mass ejections occur when that energy is released in a very explosive way.

Alex Young, a heliophysicist at Goddard Space Flight Center, said it is hard to say what is and isn't unusual when it comes to the sun.

"We've only been observing the sun in lots of detail in the last 50 years," he said.

"That's not that long considering it's been around for 4.5 billion years." And it's not like astronomers have never seen the sun this quiet before.

Three years ago, on Aug. 14, 2011 it was completely free of sunspots and, as Phillips points out, that year turned out to have relatively high solar activity overall with several X-class flares.

So in that case, the spotless sun was just a "temporary intermission," as he writes on his web site.

Whether this quiet period will be similarly short-lived or if it will last longer remains to be seen.

"You just can't predict the sun," Phillips said.

NASA STEREO A & B Spacecraft Communications to be Blocked by the Sun - Video

NASA Stereo Project team have stated that communication with the two STEREO spacecraft will soon cease when the sun blocks Earth's view of them. This position is known in astronomy as a superior conjunction.

This will happen for STEREO-Ahead from March 24 to July 7, 2015. STEREO-Behind will be in superior conjunction from January 22 to March 23, 2015.

During this period the NASA Stereo Project team claim that at least one spacecraft will always be collecting data, but that because of their position relative to the Sun, communications will be severely reduced.

The ability of Stereo A and Stereo B to gather scientific data on the Sun and transmit data back to Earth, will be greatly reduced during 2015 and on into 2016.

NASA WISE Discovers Coldest Brown Dwarf Neighbour of the Sun

This artist's conception shows a newfound object named WISE J085510.83-071442.5, the coldest known brown dwarf. 

Credit: Penn State University/NASA/JPL-Caltech

A brown dwarf as cold as the North Pole has been discovered lurking remarkably close to our solar system, and it appears to be the coldest of its kind yet found, scientists say.

Using NASA's Wide-field Infrared Survey Explorer (WISE) and Spitzer Space Telescope, astronomers discovered the dim, "failed star" lurking just 7.2 light-years away, making it the fourth closest system to our sun.

"It's very exciting to discover a new neighbor of our solar system that is so close," Kevin Luhman, an astronomer at Pennsylvania State University's Center for Exoplanets and Habitable Worlds, said in a statement.

"And given its extreme temperature, it should tell us a lot about the atmospheres of planets, which often have similarly cold temperatures."

This diagram illustrates the locations of the star systems closest to the sun. 

Credit: Penn State University

Brown dwarfs are sometimes called failed stars because they have many of the elements of that make up stars, but they lack the huge mass needed to kick off nuclear fusion in their core.

As a result, these objects don't radiate starlight and they sometimes resemble planets.

Some are even cool enough to have atmospheres much like gas giants.

While brown dwarfs are hidden in images taken in the visible spectrum, infrared telescopes like WISE can pick up the meager glow of brown dwarfs.

Luhman and colleagues first spotted the object in WISE data. It appeared to be moving quite fast, hinting that it was close by.

The team then investigated the object using Spitzer and the Gemini South telescope on Cerro Pachon in Chile to measure its distance and temperature.

"It is remarkable that even after many decades of studying the sky, we still do not have a complete inventory of the sun's nearest neighbours," Michael Werner, the project scientist for Spitzer at NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a statement.

Dubbed WISE J085510.83-071442.5, our newfound neighbor is now the record-holder for the coldest brown dwarf, with a temperature between minus 54 and 9 degrees Fahrenheit (minus 48 to minus 13 degrees Celsius), Luhman and colleagues say.

The previous record holders were more tepid, chilling only to room temperature.

At 3 to 10 times the mass of Jupiter, the object also may be one of the least massive brown dwarfs ever found, the astronomers say.

Because it is so small, the scientists say it's possible that the body is actually a planet ejected from its star system, but brown dwarfs are known to be quite common cosmic objects.

The findings were described April 21 in The Astrophysical Journal.

NASA SDO: Giant sunspot making third rotation across surface of the sun

A massive and significantly strong sunspot is currently making its third pass across a “complex region” of the Sun, according to NASA.

Sunspots like the one currently being tracked by NASA and NOAA, are part of the active Sun regions which typically produce large solar flares and coronal mass ejections.

Sunspot AR1990 was previously labeled AR1967 while on its second rotation around the Sun, and AR1944, during its initial trip around the face of the Sun.

As previously reported by NASA, the largest solar flare of 2014 was unleashed by the Sun late last week.

The huge X Class solar flare erupted from sunspot AR1990, according to NASA’s Solar Dynamics Observatory (SDO).

The agency’s spacecraft recorder captured the gigantic bursts of plasma from the coronal mass ejection – CME.

X Class solar flares are the strongest type of solar storms. The massive solar flare was not Earth-directed, so the power grid was not in jeopardy.

If the 4.9 X Class solar flare had been directed towards Earth, the CME could have likely prompted a significant geomagnetic storm.

During such a storm charged particles smash against the Earth’s magnetic field. The Sun is currently in the most active phase of its 11-year solar cycle.

NASA SDO: Coronal Loops in an Active Region of the Sun - Video

An active region of the sun just rotating into the view of NASA's Solar Dynamics Observatory gives a profile view of coronal loops over about a two-day period, from Feb. 8-10, 2014. 

Coronal loops are found around sunspots and in active regions. These structures are associated with the closed magnetic field lines that connect magnetic regions on the solar surface. 

Many coronal loops last for days or weeks, but most change quite rapidly. This image was taken in extreme ultraviolet light.

Image Credit: NASA/Solar Dynamics Observatory

The Sun reverses its magnetic poles - Video

This visualization shows the position of the sun's magnetic fields from January 1997 to December 2013. The field lines swarm with activity:

The magenta lines show where the sun's overall field is negative and the green lines show where it is positive.

A region with more electrons is negative, the region with less is labeled positive. Additional gray lines represent areas of local magnetic variation.

The entire sun's magnetic polarity, flips approximately every 11 years—though sometimes it takes quite a bit longer—and defines what's known as the solar cycle.

The visualization shows how in 1997, the sun shows the positive polarity on the top, and the negative polarity on the bottom.

Over the next 12 years, each set of lines is seen to creep toward the opposite pole eventually showing a complete flip.

By the end of the movie, each set of lines are working their way back to show a positive polarity on the top to complete the full 22 year magnetic solar cycle.

At the height of each magnetic flip, the sun goes through periods of more solar activity, during which there are more sunspots, and more eruptive events such as solar flares and coronal mass ejections, or CMEs.

The point in time with the most sunspots is called solar maximum.

Image showing the sun's magnetic fields on Jan. 1, 1997, June 1, 2003, and Dec. 1, 2013. Green indicates postive polarity. Purple is negative.

Learn more about the sun's activity from Dr Alex Young.


Alex Young is interviewed about the current solar cycle and what a magnetic flip means for the earth and NASA's study of magnetic fields

NASA SDO: Giant Convection cells found on the Sun

Giant cell flow trajectories on the Sun for June 8, 2010. 

The underlying cell pattern shows westerly winds in red and easterly winds in blue. 

Credit: David Hathaway /NASA

A trio of researchers with affiliations with NASA and several U.S. institutions has found the elusive giant convection cells suspected for nearly a half century to exist on and within the sun.

In their paper published in the journal Science, the team describes how they used data from a NASA Solar observatory (SDO) that captured solar information every 45 seconds over a several month period which allowed the researchers to track the slow movement of the giant cells.

The sun generates a lot of heat in its core, of course—heat that is conveyed to its outer portions and eventually into space.

That process occurs due to convection, and scientists have known about two types of convection sources (known as cells) for quite some time: granules and super granules—the former are small and travel very rapidly while the latter are planet sized and travel less swiftly.

A close-up of tight packs of coils around one active region (Nov. 18-19, 2013). 

The bundles of coils are actually charged particles swirling along magnetic field lines. 

Other field lines heading off to the left are more elongated and tapered. 

The images were taken in extreme ultraviolet light. 

Credit: Solar Dynamics Observatory.

Scientists have suspected for half a century that there is a third type of cell, a giant, also at play and that they have perhaps an even bigger impact on moving not just heat through the sun, but magnetism as well.

In this new effort, the researchers report that they've been able to definitively identify such cells, moving them from theory, to an observed phenomenon.

The reason that researchers have had so much difficulty in identifying giant cells, is because they move so slowly.

In finally finding them, the researchers have discovered that they move only at about ten meters per second—which when compared with the immense size of the sun, means they are not really going to stand out.

To get past that problem, the researchers looked at minute-by-minute data from NASA's Solar Dynamics Observatory.

Averaging the data allowed for observation of large groups of super granules being moved by something else—giant cells.

Besides proving theory correct, identifying giant cells on the sun might help to better predict solar events that have a direct impact on us—solar flares, coronal mass ejections, etc.—all can wreak havoc on man-made electronics.

Figuring out how to predict such events and to determine their size in advance could go a long way towards helping to build a system to automatically shut down sensitive equipment before such an event occurs.

More information: Giant Convection Cells Found on the Sun, Science 6 December 2013: Vol. 342 no. 6163 pp. 1217-1219 DOI: 10.1126/science.1244682

Irish Radio observatory finds link: solar storms and radio bursts

New research by scientists at Trinity College Dublin, University College London, and the University of Hawai'i, published online in Nature Physics, has shown for the first time a direct link between solar storms, shock waves and solar radio bursts.

The Sun gives light and heat that makes life possible on Earth.

It can, however, have more sinister effects, sometimes unleashing huge eruptions of hot gas, called solar storms, which carry billions of tons of matter travelling at millions of kilometres an hour in Earth's direction.

These storms can be accompanied by solar radio bursts, which can cause damaging effects on many of the technologies that we rely on in our everyday lives.

Eoin Carley

"Radio bursts from solar storms can have adverse effects on both satellite and terrestrial communications. In fact, mobile phone networks can experience increased dropped-calls during periods of increased solar activity," said Eoin Carley, Irish Research Council PhD student at the School of Physics, Trinity College Dublin and first author on a recent paper on this topic in Nature Physics.

Despite decades of study, the link between solar storms and solar radio bursts has remained unclear.

This led Professor Peter Gallagher, a solar physicist at Trinity's School of Physics, to establish a radio observatory at Birr Castle in the midlands of Ireland to monitor solar radio bursts.

"What we have found is fascinating – a real insight into how solar radio bursts are created", said Professor Gallagher.

"Using antennas at Trinity's Rosse Observatory in Birr Castle together with images from NASA's STEREO and Solar Dynamics Observatory spacecraft, we have identified a missing link between solar storms and radio bursts."

Birr Castle Observatory

The findings, which were published online this week in Nature Physics, show that solar storms create huge shock waves that race through the solar atmosphere at millions of kilometres per hours.

As they do, they can accelerate electrons to huge energies, which then produce radio waves.

"Our results not only give an insight into the fundamental physics of explosions on the Sun, but enable us to better understand how the Sun affects the Earth and potentially its impacts on our daily lives" according to Carley.

NASA Solar Dynamics Observatory (SDO): Untangling motion inside the Sun

Observations by the Helioseismic and Magnetic Imager on NASA's Solar Dynamics Observatory show a two-level system of circulation inside the sun. 

Such circulation is connected to the flip of the sun's north and south magnetic poles that occurs approximately every 11 years. 

Credit: Stanford University

Using an instrument on NASA's Solar Dynamics Observatory, called the Helioseismic and Magnetic Imager (HMI), scientists have overturned previous notions of how the sun's writhing insides move from equator to pole and back again, a key part of understanding how the dynamo works.

Modeling this system also lies at the heart of improving predictions of the intensity of the next solar cycle.

Using SDO, scientists see a performance of explosions and fountains on the solar surface. Shots of solar material leap into the air.

Dark blemishes called sunspots grow, combine and disappear as they travel across the sun's face. Bright loops of charged particles – captured by magnetic fields dancing around the sun – hover in the atmosphere.

This dynamic display is all powered by a complex, ever-changing magnetic current inside the sun known as the dynamo.

This magnetic system flips approximately every 11 years, with magnetic north and magnetic south switching poles.

This process is an integral part of the sun's progression toward a pinnacle of solar activity, known as solar maximum.

The team's recent results show that, instead of a simple cycle of flow moving toward the poles near the sun's surface and then back to the equator, the material inside the sun shows a double layer of circulation, with two such cycles on top of each other.

The results appear online in the Astrophysical Journal Letters on Aug. 27, 2013.

"For decades people have known that the solar cycle depends on the poleward flow or material, changing the magnetic fields from one cycle to the next," said Philip Scherrer, principal investigator for HMI at Stanford University in Stanford, Calif.

"We mapped out what we believed to be the flow pattern in the 1990s, but the results didn't quite make sense."

Since the mid-1990s researchers have been observing movement inside the sun using a technique called helioseismology.

The technique makes use of the fact that waves course across the sun, back and forth, oscillating with an approximately five minute period.

Such waves are similar to the seismic waves that spread out under the ground during an earthquake. By monitoring the oscillations seen at the surface of the sun, scientists can gather information about the material through which the waves traveled, including what the material is made of and how fast and in what direction it is moving.

More information: iopscience.iop.org/2041-8205/774/2/L29/pdf/2041-8205_774_2_L29.pdf

Solar Photographer Spots Giant Snake-Like Tendril on the Sun

Astrophotographer John Chumack took this photo of a solar filament. 

The image was taken from his backyard in Dayton, Ohio on Aug. 11, 2013.

Credit: John Chumack | www.galacticimages.com

A photographer and die-hard solar observer has captured absolutely stunning views of a colossal filament of super-hot plasma snaking its way across the surface of the sun.

Veteran astrophotographer John Chumack took the new sun photos on Aug. 11 despite cloudy weather from his backyard in Dayton, Ohio, using a DMK 21 and DMK 31 Cameras and Lunt Hydrogen Alpha Solar Scope.

The close-up image is 1/77-second exposures and the full disk shots 1/436-second exposure.

What looks like a snake-like cloud in the new sun photos is actually a solar filament made of primarily charged hydrogen gas.

The sun’s magnetic field holds the gas in the atmosphere giving it the shape seen in these images.

The filament appears dark because it is cooler than its surroundings. These filaments might remain over the sun’s surface for months.

Big Bear Observatory (BBSO): Remarkable details of the Sun now available

The most precise sunspot image ever taken is shown. 

With the unprecedented resolution of the Big Bear Solar Observatory's New Solar Telescope (NST), many, previously unknown, small-scale features are revealed.

They include the twisting flows along the penumbra's less dark filaments, as well as the complicated dynamical motion in the light bridge vertically spanning the darkest part of the umbra, as well as the dark cores of the small bright points (umbra dots) apparent in the umbra.

The telescope is currently being upgraded to include the only solar multi-conjugate adaptive optics system to fully correct atmospheric distortion over a wide field of view, as well as the only fully cryogenic solar spectrograph for probing the sun in the near infrared.

Other instruments have been brought on-line since 2009, to enable the NST to probe the sun with its full scientific capability for measuring magnetic fields and dynamic events using visible and infrared light. 

Credit: BBSO/NJIT

Researchers at NJIT's Big Bear Solar Observatory (BBSO) in Big Bear, CA have obtained new and remarkably detailed photos of the Sun with the New Solar Telescope (NST).

The photographs reveal never-before-seen details of solar magnetism revealed in photospheric and chromospheric features.

"With our new generation visible imaging spectrometer (VIS)," said Wenda Cao, NJIT Associate Professor of Physics and BBSO Associate Director, "the solar atmosphere from the photosphere to the chromosphere, can be monitored in a near real time."

"One image was taken with VIS on May 22, 2013 in H-alpha line center. The lawn-shaped pattern illustrates ultrafine magnetic loops rooted in the photosphere below."

Wenda Cao

The other photospheric photograph is the most precise sunspot image ever taken: A textbook sunspot that looks like a daisy with many petals.

The dark core of the spot is the umbra and the petals are the penumbra. "With the unprecedented resolution of BBSO's NST, many previously unknown small-scale sunspot features can now be perceived," said Cao.

In particular, there are the twisting flows along the penumbra's less dark filaments, the complicated dynamic motion in the light bridge vertically spanning the umbra's darkest part and the dark cores of the small bright points or umbra dots.

BBSO has been under NJIT's management since 1997 when NJIT took over the facility from California Institute of Technology.

Philip R. Goode

The founder and executive director has been NJIT Distinguished Professor Philip R. Goode, a Fellow of the American Physical Society and the American Association for the Advancement of Science and the American Geophysical Union.

Goode led the project, which was completed in 2009, to build the world's most capable solar telescope at BBSO. The new1.6 meter clear aperture, off-axis instrument is the world's largest solar aperture telescope.

This image was taken with the visible imaging spectrometer on May 22, 2013, in H-alpha line center by the New Solar Telescope (NST) at Big Bear Solar Observatory (BBSO), Calif.

The lawn-shaped pattern shows ultrafine magnetic loops rooted on the photosphere. 

The telescope is currently being upgraded to include the only solar multi-conjugate adaptive optics system to correct atmospheric distortion over a wide field of view, as well as the only fully cryogenic solar spectrograph for probing the sun in the near infrared.

Other instruments have been brought on-line since 2009, to enable the NST to probe the sun with its full scientific capabilities for measuring magnetic fields and dynamic events using visible and infrared light. 

Credit: BBSO/NJIT

The telescope is currently being upgraded to include the only solar multi-conjugate adaptive optics system with the goal being to fully correct atmospheric distortion over a wide field of view, as well as the only fully cryogenic solar spectrograph for probing the Sun in the near infrared.

Other instruments have been brought on-line since 2009, to enable the NST to probe the Sun with its full scientific capability for measuring magnetic fields and dynamic events using visible and infrared light.

The Sun's Heliosphere is about to flip

An artist's concept of the heliospheric current sheet, which becomes more wavy when the sun's magnetic field flips.

Something big is about to happen on the sun.

According to measurements from NASA-supported observatories, the sun's vast magnetic field is about to flip.

Todd Hoeksema

"It looks like we're no more than 3 to 4 months away from a complete field reversal," says solar physicist Todd Hoeksema of Stanford University. "This change will have ripple effects throughout the solar system."

The sun's magnetic field changes polarity approximately every 11 years. It happens at the peak of each solar cycle as the sun's inner magnetic dynamo re-organizes itself.

The coming reversal will mark the midpoint of Solar Cycle 24. Half of 'Solar Max' will be behind us, with half yet to come.

Hoeksema is the director of Stanford's Wilcox Solar Observatory, one of the few observatories in the world that monitor the sun's polar magnetic fields.

The poles are a herald of change. Just as Earth scientists watch our planet's polar regions for signs of climate change, solar physicists do the same thing for the sun.

Magnetograms at Wilcox have been tracking the sun's polar magnetism since 1976, and they have recorded three grand reversals—with a fourth in the offing.

Solar physicist Phil Scherrer, also at Stanford, describes what happens: "The sun's polar magnetic fields weaken, go to zero, and then emerge again with the opposite polarity. This is a regular part of the solar cycle."

A reversal of the sun's magnetic field is, literally, a big event. The domain of the sun's magnetic influence (also known as the "heliosphere") extends billions of kilometers beyond Pluto.

Changes to the field's polarity ripple all the way out to the Voyager probes, on the doorstep of interstellar space.

When solar physicists talk about solar field reversals, their conversation often centers on the "current sheet."

The current sheet is a sprawling surface jutting outward from the sun's equator where the sun's slowly-rotating magnetic field induces an electrical current.

The current itself is small, only one ten-billionth of an amp per square meter (0.0000000001 amps/m2), but there's a lot of it: the amperage flows through a region 10,000 km thick and billions of kilometers wide.

Electrically speaking, the entire heliosphere is organized around this enormous sheet.

During field reversals, the current sheet becomes very wavy. Scherrer likens the undulations to the seams on a baseball.

As Earth orbits the sun, we dip in and out of the current sheet. Transitions from one side to another can stir up stormy space weather around our planet.

Cosmic rays are also affected. These are high-energy particles accelerated to nearly light speed by supernova explosions and other violent events in the galaxy.

Cosmic rays are a danger to astronauts and space probes, and some researchers say they might affect the cloudiness and climate of Earth.

The current sheet acts as a barrier to cosmic rays, deflecting them as they attempt to penetrate the inner solar system. A wavy, crinkly sheet acts as a better shield against these energetic particles from deep space.

As the field reversal approaches, data from Wilcox show that the sun's two hemispheres are out of synch.

"The sun's north pole has already changed sign, while the south pole is racing to catch up," says Scherrer.

"Soon, however, both poles will be reversed, and the second half of Solar Max will be underway."

When that happens, Hoeksema and Scherrer will share the news with their colleagues and the public.

The Sun's Heliosphere, the Bow Shock and Ripple effect

Image of sun courtesy of NASA.

A new study co-authored by Boston University astronomers indicates that a bow shock (a dynamic boundary between the Sun's heliosphere and the interstellar medium) is highly likely.

These findings challenge recent predictions that no such bow shock would be encountered.

The researchers base their expectation of finding a bow shock on a new magneto-hydrodynamic simulation that confirmed a theoretically expected slow bow shock (SBS) ahead of the heliosphere.

The new research supports the idea that the sun, like a boat moving through water, forms a crescent-shaped shockwave as it moves through interstellar gas.

The study, titled "A slow bow shock ahead of the heliosphere," was published recently in the journal Geophysical Research Letters.

Bertalan Zieger

In the current study, Bertalan Zieger, lead author and research scientist at BU's Center for Space Physics, and colleagues predict that a slow bow shock should exist ahead of the heliosphere.

This challenges some recent models that argued no bow shock at all would be found.

Those studies, which used the Interstellar Boundary Explorer (IBEX) satellite to measure the speed of interstellar particles entering the solar system near the edge of the heliosphere, suggested that the sun was moving too slowly through interstellar space (at 52,000 miles an hour) to create a bow shock.

However, the bow shock that they refer to is what is called a fast bow shock.

The new study shows that a slow type is possible: IBEX observations also indicate that the interstellar wind is slower than the fast and the intermediate wave, but faster than the slow wave.

Using these observations, the researchers conducted a magneto-hydrodynamic simulation that predicts a slow bow shock should exist in front of the heliosphere.

These projections could soon be confirmed by actual data: Voyager 1 is heading toward the slow bow shock, while Voyager 2 is not, which means that the two spacecraft are expected to encounter different interstellar plasma populations beyond the heliopause.

Confirmation of the existence of a bow shock could have important implications for our understanding of the nature of the interstellar magnetic field that the Voyagers will encounter ahead of the heliopshere, including whether the slow bow shock filters the influx of high-energy cosmic rays into the heliosphere.

More information: Geophysical Research Letters, Vol. 40, 1–6, doi: 10.1002/grl.50576, 2013

NASA SDO Image: Fragments falling into the Sun

An image of a portion of the Sun's active corona as seen in the ultraviolet with the Solar Dynamics Observatory. 

A giant flare is present, with the Earth shown to size in the inset.

Stars form as gravity coalesces the gas and dust in an interstellar cloud until the material develops clumps dense enough to become stars.

Even after a star begins to burn its nuclear fuel it continues to grow in mass as it accumulates matter from its natal cloud - and also from a surrounding ring of circum-stellar material that develops. (This disk can subsequently produce planets.)

Mass accretion from the circum-stellar disk onto the stellar surface is expected to play an important role in star formation, especially in its later stages, but the process is very difficult to measure on other stars, leaving scientists uncertain about the many details.

Young low-mass stars are thought to interact with their circum-stellar disks via magnetic funnels. Hot gas plasma accretes along these funnels, falling onto the stellar surface at velocities of hundreds of kilometers per second.

Most of the evidence for this accretion comes from excess emission seen at infrared, optical, ultraviolet, and even X-ray wavelengths.

Current models suggest that an impact region is rather complex because of the interplay between the radiation and the hot gas.

According to models, the in-falling material, after colliding back onto the surface, is heated to millions of degrees and partially sinks into the star's chromosphere.

The impact can also drive strong motions and feed material back into surrounding coronal structures.

The streams could be highly structured in both density and velocity, and result in inhomogeneous (non-uniform) impact spots.

All these ideas are now being tested, thanks in part to the remarkable Solar Dynamics Observatory satellite that was launched in 2010 with an instrument team that included Harvard-Smithsonian SAO scientists.

In the latest issue of Science Express, SAO astronomer Paola Testa and five colleagues report discovering that fragments of ejected material from a solar flare fell back onto the Sun's surface and produced intense bursts of emission resembling those thought to occur in young stars.

The scientists simulated the infall, and found good agreement between the models and observations. It seems likely that studies of our own mature Sun will help unravel a mystery about how young stars develop.

NASA SDO: New CME Vortex Sightings on the Sun - Video

For a 38 hour spell (June 3-4, 2013) the Solar Dynamics Observatory captured plasma whirling through a magnetic dance across the Sun's surface. Multiple 'sun tornadoes' appear to be supporting a long solar filament like pillars of fire. Credit: NASA / SDO

NASA SDO Image: Extensive Coronal Hole in the Sun

Credit: NASA/SDO/AIA

An extensive coronal hole on the sun rotated towards the Earth during the week of May 28-31, 2013.

The massive coronal area represents one of the largest in a year or more.

Coronal holes produce strong solar wind gusts that carry solar particles out to the Earth’s magnetosphere and beyond.

These holes appear darker in extreme ultraviolet light images (as in this photo, which combines three wavelengths of UV light) because less matter exists at the temperatures observed.

The coronal hole may generate some auroral displays on Earth.

STEREO, SOHO and SDO detect an Earth-facing CME from the Sun

A combined view of the coronal mass ejection, or CME, that occurred on May 17, 2013, at 5:36 EDT. 

The center yellow image was captured by NASA's Solar Dynamics Observatory (SDO) and shows the sun as seen in UV light, in the 171 Angstrom wavelength. 

The SDO image is superimposed on top of an image from the Solar and Heliospheric Observatory (SOHO) showing the CME propagating into space. 

Credit: NASA /SDO /Goddard, ESA and NASA SOHO

On 5:24 a.m. EDT on May 17, 2013, the sun erupted with an Earth-directed coronal mass ejection or CME, a solar phenomenon that can send billions of tons of solar particles into space that can reach Earth one to three days later and affect electronic systems in satellites and on the ground.

Experimental NASA research models, based on observations from NASA's Solar Terrestrial Relations Observatory (STEREO), show that the CME left the sun at speeds of around 745 miles per second.

The solar material in CMEs cannot pass through the atmosphere to affect humans on Earth.

Not to be confused with a solar flare, a CME can cause a space weather phenomenon called a geomagnetic storm, which occurs when they connect with the outside of the Earth's magnetic envelope, the magnetosphere, for an extended period of time.

The CME may also pass by Spitzer and its mission operators have been notified. If warranted, operators can put spacecraft into safe mode to protect the instruments from the solar material.

Major X1.7-Class Solar Flare Erupts from the Sun - Strongest of 2013

The sun unleashed a colossal Mother's Day solar flare on Sunday (May 12) in what has become the most powerful solar eruption of the year.

The giant solar flare, which registered as one of the largest eruptions the sun can unleash, peaked Sunday night at 10:17 p.m. EDT (0217 GMT) and was captured on camera by NASA's Solar Dynamics Observatory.

It sparked an hour-long high-frequency radio blackout, according to the Space Weather Prediction Center (SWPC) overseen by the National Oceanic and Atmospheric Administration (NOAA).

Sunday's solar flare registered as an X1.7-class sun eruption — the strongest type of solar flare the sun can fire off, according to the SWPC officials.


A close-up of an an X1.7-class solar flare on May 12, 2013 as seen by NASA's Solar Dynamics Observatory.

When aimed directly at Earth, X-class solar flares can pose a risk to astronauts and satellites in orbit, as well as interfere with communications and GPS signals on the ground.

They can also super-charge Earth's northern lights displays by bombarding the planet with solar particles, triggering awesome aurora light shows.

Coronal Mass Ejection (CME) From the Sun Directed at Earth

Early on March 17, 2013, the coronal mass ejection (CME) from March 15 interacted with the giant magnetic bubble surrounding Earth, the magnetosphere, causing a G1-class geomagnetic storm. Storms of this strength have caused auroras near the poles but have not disrupted electrical systems on Earth or interfered with GPS or satellite-based communications systems. Credit: NASA.

On March 15, 2013, at 2:54 a.m. EDT, the sun erupted with an Earth-directed coronal mass ejection (CME), a solar phenomenon that can send billions of tons of solar particles into space and can reach Earth one to three days later and affect electronic systems in satellites and on the ground.

Experimental NASA research models, based on observations from the Solar Terrestrial Relations Observatory (STEREO) and ESA/NASA's Solar and Heliospheric Observatory, show that the CME left the sun at speeds of around 900 miles per second, which is a fairly fast speed for CMEs.

Historically, CMEs at this speed have caused mild to moderate effects at Earth.

The NASA research models also show that the CME may pass by the Spitzer and Messenger spacecraft. NASA has notified their mission operators.

There is, however, only minor particle radiation associated with this event, which is what would normally concern operators of interplanetary spacecraft since the particles can trip on board computer electronics.

Not to be confused with a solar flare, a CME is a solar phenomenon that can send solar particles into space and reach Earth one to three days later.

Earth-directed CMEs can cause a space weather phenomenon called a geomagnetic storm, which occurs when they connect with the outside of the Earth's magnetic envelope, the magnetosphere, for an extended period of time.

In the past, geomagnetic storms caused by CMEs such as this one have usually been of mild to medium strength.