CME – astroengine.com

Psychedelic Simulation Showcases the Ferocious Power of a Solar Flare

Scientists are closing in on a better understanding about how these magnetic eruptions evolve

[Mark Cheung, Lockheed Martin, and Matthias Rempel, NCAR]

For the first time, scientists have created a computer model that can simulate the evolution of a solar flare, from thousands of miles below the photosphere to the eruption itself in the lower corona — the sun’s multimillion degree atmosphere. And the results are not only scientifically impressive, the visualization is gorgeous.

I’ve always had a fascination with the sun — from how our nearest star generates its energy via fusion reactions in its core, to how the tumultuous streams of energetic plasma slams into our planet’s magnetosphere, igniting spectacular aurorae. Much of my interest, however, has focused on the lower corona; a region where the intense magnetic field emerges from the solar interior and reaches into space. With these magnetic fields comes a huge release of hot plasma that is channeled by the magnetism to form beautiful coronal loops. Intense regions of magnetism can accumulate in violently-churning “active regions,” creating sunspots and explosive events — triggered by large-scale magnetic reconnection — such as flares and coronal mass ejections (or CMEs). This is truly a mysterious place and solar physicists have tried to understand its underlying dynamics for decades.

The eruption of an X-class solar flare in the sun’s multimillion degree corona [NASA/SDO]

Now, with increasingly-sophisticated solar observatories (such as NASA’s Solar Dynamics Observatory), we are getting an ever more detailed look at what’s going on inside the sun’s deep atmosphere and, with improvements of theoretical models and increases in computer processing power, simulations of the corona are looking more and more like the real thing. And this simulation, detailed in the journal Nature Astronomy, is truly astonishing.

In the research, led by researchers at the National Center for Atmospheric Research (NCAR) and the Lockheed Martin Solar and Astrophysics Laboratory, the evolution of a solar flare has been modeled. This simulation goes beyond previous efforts as it is more realistic and creates a more complete picture of the range of emissions that can be generated when a solar flare is unleashed.

One of the biggest questions hanging over solar (and indeed, stellar) physics is how the sun (and other stars) heat the corona. As we all know, the sun is very hot but its corona is too hot; the photosphere is a few thousand degrees, whereas, only just above it, the coronal plasma skyrockets to millions of degrees, generating powerful radiation beyond what the human eye can see, such as extreme-ultraviolet and X-rays. Basic thermodynamics says that this shouldn’t be possible — this situation is analogous to finding the air surrounding a light bulb is hotter than the bulb’s glass. But what our sun has that a light bulb does not is a powerful magnetic field that dictates the size, shape, temperature and dynamics of the plasma our sun is blasting into space. (If you want some light reading on the subject, you can read my PhD thesis on the topic.)

“This work allows us to provide an explanation for why flares look like the way they do, not just at a single wavelength, but in visible wavelengths, in ultraviolet and extreme ultraviolet wavelengths, and in X-rays. We are explaining the many colors of solar flares.”
Mark Cheung, staff physicist at Lockheed Martin Solar and Astrophysics Laboratory.

The basis of this new simulation, however, investigates another mystery: How and why do solar flares erupt and evolve? It looks like the research team might be on the right track.

When high-energy particles from the sun impact our atmosphere, vast light shows called auroras can be generated during the geomagnetic storm, as shown in this view from the International Space Station [NASA]

Inspired by a powerful flare that was observed in the corona in March 2014, the researchers provided their magnetohydrodynamic model with an approximation of the conditions that were observed at the time. The magnetic conditions surrounding the active region were primed to generate a powerful X-class flare (the most powerful type of solar flare) and several less powerful (but no less significant) M-class flares. So, rather than forcing their simulation to generate flares, they re-enacted the conditions of the sun that were observed and just let their simulation run to create its own flares.

“Our model was able to capture the entire process, from the buildup of energy to emergence at the surface to rising into the corona, energizing the corona, and then getting to the point when the energy is released in a solar flare,” said NCAR scientist Matthias Rempel in a statement. “This was a stand-alone simulation that was inspired by observed data.

“The next step is to directly input observed data into the model and let it drive what’s happening. It’s an important way to validate the model, and the model can also help us better understand what it is we’re observing on the sun.”

Solar flares, CMEs and even the solar wind can have huge impacts on our technological society. The X-rays blasting from the sun’s atmosphere millions of miles away can have dramatic impacts on the Earth’s ionosphere (impacting communications) and can irradiate unprotected astronauts in space, for example. CMEs can be launched from the corona and arrive at Earth orbit in a matter of hours or days, triggering geomagnetic storms that can impact entire power grids. We’re not just talking a few glitches on your cellphone here; satellites can be knocked out, power supplies neutralized and global communications networks interrupted. It’s simulations like these, which aim to get to the bottom of how these solar storms are initiated, that can help us better prepare for our sun’s next big temper tantrum.

For more on this research, watch this video:

Sun Erupts With a Monster X9-Class Solar Flare — Earth Feels Its Punch

Sept_6_X9_Blend_131-171_print — Credit: NASA/SDO

This morning, the sun erupted with the most powerful solar flare in a decade, blasting the Earth’s upper atmosphere with energetic X-ray and extreme ultraviolet (EUV) radiation.

The flare was triggered by intense magnetic activity over an active region called AR2673 that has been roiling with sunspot activity for days, threatening an uptick in space weather activity. As promised, that space weather brought an explosive event at 1202 UTC (8:02 a.m. PT) that ionized the Earth’s upper atmosphere and causing a shortwave radio blackout over Europe, Africa and the Atlantic Ocean, reports Spaceweather.com.

blackoutmap — Radio blackout map: When the Earth’s ionosphere is energized by X-ray and EUV radiation from solar flares, certain radio frequencies are absorbed by increased ionization of certain layers of the atmosphere, posing issues for global radio communications (NOAA)

The powerful X9.3-class flare came after an earlier X2.2 blast from the same active region, a significant flare in itself. X-class flares are the most powerful type of solar flares.

The electromagnetic radiation emitted by flaring events affect the Earth’s ionosphere immediately, but now space weather forecasters are on the lookout for a more delayed impact of this eruption.

x-class-solar-flare — The powerful X9-class solar flare erupted from the active region (AR) 2673, a large cluster of sunspots — seen here by NASA’s Solar Dynamics Observatory (NASA/SDO)

Solar flares can create magnetic instabilities that may launch coronal mass ejections (CMEs) — basically vast magnetized bubbles of energetic solar plasma — into interplanetary space. Depending on the conditions, these CMEs may take hours or days to reach Earth (if they are Earth-directed) and can generate geomagnetic storms should they collide and interact with our planet’s global magnetic field.

Update: According to observations gathered by NASA’s STEREO-A spacecraft, the flare did produce a CME and space weather forecasters are determining its trajectory to see whether it is Earth-directed. Also, NASA has produced a series of beautiful images from the SDO, showing the flare over a range of frequencies.

Compex Magnetic Eruption Witnessed by Solar Observatories

sunnow — Solar Dynamics Observatory view of the solar disk shortly after eruption (NASA).

This morning, at 08:55 UT, NASA’s Solar Dynamics Observatory (SDO) detected a C3-class flare erupt inside a sunspot cluster. 100,000 kilometers away, deep within the solar atmosphere (the corona), an extended magnetic field filled with cool plasma forming a dark ribbon across the face of the sun (a feature known as a “filament”) erupted at the exact same time.

It seems very likely that both events were connected after a powerful shock wave produced by the flare destabilized the filament, causing the eruption.

A second solar observatory, the Solar and Heliospheric Observatory (SOHO), then spotted a huge coronal mass ejection (CME) blast into space, straight in the direction of Earth. Solar physicists have calculated that this magnetic bubble filled with energetic particles should hit Earth on August 3, so look out for some intense aurorae, a solar storm is on its way…

For more on this impressive solar eruption, read my Discovery News article, “Incoming! The Sun Unleashes CME at Earth“

Solar Cycle Prediction: “None of Our Models Were Totally Correct”

nov4flare

Predicting space weather is not for the faint-hearted. Although the Sun appears to have a predictable and regular cycle of activity, the details are a lot more complex. So complex in fact, that the world’s greatest research institutions have to use the most powerful supercomputers on the planet to simulate the most basic of solar dynamics. Once we have a handle on how the Sun’s interior is driven, we can start making predictions about how the solar surface may look and act in the future. Space weather prediction requires a sophisticated understanding of the Sun, but even the best models are flawed.

Today, another solar cycle prediction has been released by the guys that brought us the “$2 trillion-worth of global damage if a solar storm hits us” valuation earlier this month. According to NOAA scientists sponsored by NASA, Solar Cycle 24 will peak in May 2013 with a below-average number of sunspots.

“If our prediction is correct, Solar Cycle 24 will have a peak sunspot number of 90, the lowest of any cycle since 1928 when Solar Cycle 16 peaked at 78,” says Doug Biesecker of the NOAA Space Weather Prediction Center.

Although this may be considered to be a “weak” solar maximum, the Sun still has the potential to generate some impressive flares and coronal mass ejections (CMEs). Although I doubt we’ll see the record-breaking flares we saw in 2003 (pictured top), we might be hit by some impressive solar storms and auroral activity will certainly increase in Polar Regions. But just because the Sun will be more active, it doesn’t mean we will be struck by any big CMEs; space is a big place, we’d be (un)lucky to be staring directly down the solar flare barrel.

So, we have a new prediction and the solar models have been modified accordingly, but it is hard to understand why such tight constraints are being put on the time of solar maximum peak (one month in 2013) and the number of sunspots expected (90, or thereabouts). Yes, sunspot activity is increasing, but we are still seeing high-latitude sunspots from the previous cycle (Solar Cycle 23) pop up every now and again. This is normal, an overlap in cycles do occur, yet it surprises me that any definitive figures are being placed on a solar maximum that may or may not peak four years from now.

Ah, I see, it's obvious Solar Cycle 24 will look like that... is it really? (NOAA/NASA) — Tenuous link: Are you really happy with that prediction? (NOAA/NASA)

We are able to look at the history of sunspot number and we can see the cycles wax and wane, and we can pick out a cycle that most resembles the one we are going through now, but that doesn’t mean that particular cycle will happen this time around. Statistically-speaking, there’s a higher chance of a similar-looking cycle from the past happening in this 24th cycle, but predictions based on this premise are iffy to say the least.

Also, solar models are far from being complete, and many aspects of the physics behind the Sun’s internal dynamics are a mystery. The Sun really is acting strange, which is fascinating for solar physicists.

“It turns out that none of our models were totally correct,” says Dean Pesnell of the Goddard Space Flight Center, NASA’s lead representative on the panel. “The sun is behaving in an unexpected and very interesting way.”

Personally, I think we should concentrate less on predicting when or how the next solar maximum presents itself. Solar models are not going to suddenly predict the nature of the solar cycle any more than we can predict terrestrial weather systems more than a few days in advance.

Using the atmospheric weather analogy, we know the seasons cycle as the year goes on, but there is no way we can say with any degree of certainty when the hottest day of the year is going to be, or which week will yield the most rain.

The same goes for our Sun. It is vastly complex and chaotic, a system we are only just beginning to understand. We need more observatories and more solar missions with advanced optics and spectrometers (and therefore a huge injection of funding, something solar physicists have always struggled without). Even then, I strongly doubt we’ll be able to predict exactly when the peak of the solar cycle is going to occur.

That said, space weather prediction is a very important science, but long-term forecasts don’t seem to be working, why keep on releasing new forecasts when the old one was based on the same physics anyway? Predicting an inactive, active or mediocre solar maximum only seems to cause alarm (although it is a great means to keep solar physics in the headlines, which is no bad thing in my books).

I suppose if you make enough predictions, eventually one will be correct in four years time. Perhaps there will be a peak of 90 sunspots by May 2013, who knows?

If you’re blindfolded, spun around and armed with an infinite supply of darts, you’ll eventually hit the board. Hell, you’ll probably even hit the bullseye…

Source: NASA, special thanks to Jamie Rich for bringing this subject to my attention!

An Explanation For Solar Sigmoids

Hinode X-ray observation of a solar sigmoid (David McKenzie/Montana State University)

Sigmoids in the solar corona have been studied for many years, but little explanation of their formation or why they are often the seed of powerful solar flares have been forthcoming. Using high-resolution X-ray images from the Japanese-led solar mission Hinode (originally Solar-B), solar physicists have known that these very hot S-shaped structures are composed of many highly stressed magnetic flux tubes filled with energized plasma (also known as ‘fibrils’), but until now, little was known about the formation and flare eruption processes that occur in sigmoids.

Now, a team of solar physicists from the University of St Andrews believe they have found an answer using powerful magnetohydrodynamic (MHD) computer models, aiding our understanding of coronal dynamics and getting us one step closer to forecasting space weather…

Continue reading “An Explanation For Solar Sigmoids”

When the Sun is So Boring, Anything Becomes Interesting

Caption: So boring it doesn't deserve a caption (NASA/SOHO)

You know when you have those unremarkable days, those periods of time you experience you know you’ll forget tomorrow? It’s either “just another” day at work, another commute, or a Sunday where you had a beer, fell asleep, only to wake up again to realise it was too late to get up so you stayed in bed till Monday? (And no, I don’t make a habit of that. I’m sure to have at least two beers.) Most days aren’t like that for me, usually I can think of one noteworthy event that sets apart one day from the next, but sometimes it’s as if Stuff Happens™ doesn’t.

It would appear the Sun is having an extended period of time where Stuff Happens™ is at a premium, so you have to make the most of when something really does happen. In this case, the Sun released a crafty CME, thinking we wouldn’t see it…
Continue reading “When the Sun is So Boring, Anything Becomes Interesting”