Strong evidence for coronal heating theory presented

April 28, 2015, NASA
NASA's EUNIS sounding rocket examined light from the sun in the area shown by the white line (imposed over an image of the sun from NASA's Solar Dynamics Observatory) then separated the light into various wavelengths (as shown in the lined images – spectra – on the right and left) to identify the temperature of material observed on the sun.  The spectra provided evidence to explain why the sun's atmosphere is so much hotter than its surface. Credits: NASA/EUNIS/SDO

The Sun's surface is blisteringly hot at 6,000 kelvins or 10,340 degrees Fahrenheit—but its atmosphere is another 300 times hotter. This has led to an enduring mystery for those who study the Sun: What heats the atmosphere to such extreme temperatures? Normally when you move away from a hot source the environment gets cooler, but some mechanism is clearly at work in the solar atmosphere, the corona, to bring the temperatures up so high.

Clear evidence now suggests that the heating mechanism depends on regular, but intermittent explosive bursts of heat, rather than on continuous gradual heating. This solution to the coronal heating mystery was presented in a media briefing on April 28, 2015, at the Triennial Earth-Sun Summit, or TESS, meeting in Indianapolis, Indiana.

This is the inaugural meeting for TESS, which is a first of its kind: uniting the various research groups that study the Sun-Earth connection from explosions on the Sun to their effects near our home planet and all the way out to the edges of the —a research field collectively known as heliophysics. The overarching goal is to share techniques across disciplines and encourage interdisciplinary collaboration on outstanding heliophysics questions.

The coronal heating mystery is one such outstanding question. Four scientists spoke at the media briefing.

Jim Klimchuk, a solar scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, explained that the new evidence supports a theory that the Sun's corona is heated by tiny explosions called nanoflares. These are impulsive heating bursts that individually reach incredibly hot temperatures of some 10 million kelvins or 18 million degrees Fahrenheit—even greater than the average temperature of the corona—and provide heat to the atmosphere. The research evidence presented by the panel spotted this super hot solar material, called plasma, representative of a nanoflare.

"The explosions are called nanoflares because they have one-billionth the energy of a regular flare," said Klimchuk. "Despite being tiny by solar standards, each packs the wallop of a 10-megaton hydrogen bomb. Millions of them are going off every second across the Sun, and collectively they heat the corona."

The first evidence of the presence of this superhot plasma was presented by Adrian Daw, a solar scientist at Goddard and principal investigator of the Extreme Ultraviolet Normal Incidence Spectrograph, or EUNIS, sounding rocket mission. EUNIS flew on a 15-minute flight in December 2013 equipped with an instrument called a spectrograph, which can gather information about how much material is present at a given . The EUNIS spectrograph was tuned into a range of wavelengths useful for spotting material at temperatures of 10 million kelvins (18 million degrees F), the temperatures that signify nanoflares. The spectrograph unambiguously spotted this extremely hot material in active regions that visibly appeared to be quiet. In a quiet region, such hot temperatures clearly weren't due to a large explosive , and so are a smoking gun that something otherwise unobservable was heating up this area.

Daw also reported the results from another experiment launched on sounding rockets in 2012 and 2013 that imaged soft X-rays from the corona. These results, too, confirmed the presence of superhot plasma on the Sun.

Iain Hannah, an astrophysicist at the University of Glasgow in Scotland, spoke about NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, which typically examines X-rays from distant stars and black holes. However, it is also capable of observing the much brighter light of the Sun—something most astronomical observatories can't do.

"X-rays are a direct probe into the high-energy processes of the Sun," said Hannah.

NuSTAR saw X-rays that are signatures of superhot plasma in non-flaring active regions. While the sounding rocket experiments observed the energy produced by these nanoflares, NuSTAR is also able to look for the X-ray signatures of energetic particles. Understanding what and how particles are accelerated out from these smaller nanoflare explosions can help scientists understand what processes create them.

Stephen Bradshaw, a solar astrophysicist at Rice University in Houston, Texas, was the last speaker. Bradshaw used a sophisticated computational model to demonstrate why spotting signatures of the nanoflares has been so difficult and how the new evidence will help researchers go forward to improve theories on the details of coronal heating—one day allowing heliophysics researchers to at last solve the coronal heating mystery.

Explore further: Best evidence yet for coronal heating theory detected by NASA sounding rocket

More information: aas.org/meetings/tess2015

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Stevepidge
1 / 5 (7) Apr 28, 2015
So... The the bulk of the heat comes from coronal micro flares... not a nuclear furnace core? Hmm, what could be the CAUSE of such flares? explaining such activity with some kind of fusion reaction is ridiculous par excellence.
cantdrive85
1 / 5 (6) Apr 28, 2015
Brilliance, that's AWESOME! They were able to detect plasma on the Sun, which consists of 100% plasma. I think a Nobel is in the offing....
rufusgwarren
2 / 5 (4) Apr 28, 2015
It would be an interesting study to first map these incidents over time to define similar structure and scale. From the spectral density plot we see the energy distribution and events as a function of location, relative to us. Can a body force (section not created with data so what fits) be simulated that would create this effect, spectra, shape, motion, speed based upon known theory. The above analysis only requires a good camera, this is not a theory, this is an interpreted observation. not with rigorous data collection.
rufusgwarren
1 / 5 (3) Apr 28, 2015
A report on a "theory" would require at least a 20 year observational period with attributes corroborated. There are no attributes defined, except, " I see fire!"
rufusgwarren
2.3 / 5 (3) Apr 28, 2015
How does it manifest, "From a bunch of little fires!" may I see your time domain analysis of the energy spectrum prior to these events?
rufusgwarren
1 / 5 (2) Apr 28, 2015
"May we see the comparison to your simulation results and your prediction of this event and how well it matches the data?"

"Oh, I just noticed these flares. You know big flares that equal a lot of little flares."

"So, you don't really have a theory that explains this cooperation among the flares to create your temperature difference. It's because of fire?"
HannesAlfven
2 / 5 (7) Apr 28, 2015
I've over time come to suspect that this is an instance where the wrong question is possibly being asked. I was under the impression that temperature is a measure of the random "thermal" movements of electrons, so what does it mean to take the temperature of a plasma where the charged particles are oftentimes moving together, oftentimes in what appear to be vortices? Dramatic changes in temperature probably simply reflect dramatic changes in the random movements between the various layers of the Sun. Within the context of plasmas, I'm not sure that this is actually an anomaly at all, and I think it might simply be a distraction from more important anomalies.
rufusgwarren
2.3 / 5 (3) Apr 29, 2015
I've over time come to suspect that this is an instance where the wrong question is possibly being asked. I was under the impression that temperature is a measure of the random "thermal" movements of electrons,


Temperature is a measure of of the number and magnitude of available states a system can take, typically a quantum mechanical scale. Sort of correct. What you feel is many different quantum (heat) phonoms exchanging energy with your body. The more states that exist, the greater number of damaging reactions and more intense phonoms, i.e. temperature. Each reaction has its own choice of phonom. Phonom, photon, neutrino, ... are an event within the Field, Field-Event, not a particle. Phonoms are usually molecular momentum, atomic phonoms, motion of the nucleuse is close to molecualr phonoms. Particles also transmit, magnetic phonoms, partcle momemtum, collision response(dq/dt) ... collision, containment, ... See Boltzmann constant and QM
Stevepidge
1 / 5 (2) Apr 29, 2015
That picture is so cool I had to make it my wallpaper.

Also, for the sun truthers...
http://www.physics4kids.com/


Your sources are duly noted. I thought it was just a giant flaming marshmallow.
cantdrive85
1 / 5 (2) Apr 30, 2015


Also, for the sun truthers...
http://www.physics4kids.com/


You think complex solar plasma processes are taught to children? Hell they aren't even accurately taught to astrophysicists.

Your other link, header at top of page;

"A Look Inside Our Nearest Star!"

Presented as facts, maybe you can point to any in situ measurements which supports such nonsense. Good luck! I will not hold my breath. At least we know you're an easily duped simpleton.
Steve 200mph Cruiz
5 / 5 (2) May 04, 2015
Jesus you guys are dumb
katesisco
1 / 5 (2) May 21, 2015

well, if you are wondering how these 'naoflares' of intermittent but continual nature form, perhaps one should ask the author of the theory: http://en.wikiped...e_Parker
Myself, I think Sol is a fading magnetar.
rufusgwarren
not rated yet May 21, 2015
QM ok. However, imagine a 4D space, see energy as a wave from the atomic scale, imagine two waves fronts moving toward an intercept point, from different directions, define which "modal" points we are talking about. In a contained four dimensional space, every event is defined! Imagine the force required to cause like particles to collide, i.e. definable. A lot easier from the bottom up, before the top down.
rufusgwarren
not rated yet May 21, 2015
Is the core of the sun another sort of particle stability, i.e. a confined set of allowed states.

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