The mystery of nanoflares

March 20, 2015 by Dr. Tony Phillips, NASA
X-rays stream off the sun in this image showing observations from by NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, overlaid on a picture taken by NASA's Solar Dynamics Observatory (SDO). Credit: NASA

When you attach the prefix "nano" to something, it usually means "very small." Solar flares appear to be the exception.

Researchers are studying a type of explosion on the called a 'nanoflare.' A billion times less energetic than ordinary flares, nanoflares have a power that belies their name.

"A typical 'nanoflare' has the same energy as 240 megatons of TNT," says physicist David Smith of UC Santa Cruz. "That would be something like 10,000 atomic fission bombs."

The sun can go days, weeks or even months without producing an ordinary . Nanoflares, on the other hand, are crackling on the sun almost non-stop.

"They appear as little brightenings of the at extreme ultraviolet and X-ray wavelengths," continues Smith. "The first sightings go back to Skylab in the 1970s."

The relentless crackle of nanoflares might solve a long-standing mystery in solar physics: What causes the sun's corona to be so hot?

Imagine standing in front of a roaring fire. You feel the warmth of the flames. Now back away. You get cooler, right?

That's not how it works on the sun. The visible surface of the sun has a temperature of 5500 C. Moving away from the surface should provide some relief. Instead, the sun's upper atmosphere, known as the "," sizzles at a million degrees—a temperature almost 200 times higher than that of the roaring furnace below.

For more than a half-century, astronomers have tried to figure out what causes the corona to be so hot. Every year or so, a press release appears purporting to solve the mystery, only to be shot down by a competing theory a year or so later. It is one of the most vexing problems in astrophysics.

Smith thinks nanoflares might be involved. For one thing, they appear to be active throughout the solar cycle, which would explain why the corona remains hot during Solar Minimum. And while each individual nanoflare falls short of the energy required to heat the sun's atmosphere, collectively they might have no trouble doing to job.

To investigate this possibility, Smith turned to a telescope designed to study something completely different.

Launched in 2012, NASA's NuSTAR X-ray telescope is on a mission to study black holes and other extreme objects in the distant cosmos. Solar scientists first thought of using NuSTAR to study the sun about seven years ago, after the space telescope's design and construction was underway. Smith contacted the principal investigator, Fiona Harrison of the California Institute of Technology in Pasadena, to see what she thought.

"At first I thought the whole idea was crazy," says Harrison. "Why would we have the most sensitive high energy X-ray telescope ever built, designed to peer deep into the universe, look at something in our own back yard?"

Eventually, she was convinced. As Smith explained, NuSTAR has just the right combination of sensitivity and resolution to study the telltale X-ray flickers of nanoflares. A test image they took in late 2014 removed any doubt. NuSTAR turned toward the sun and, working together with NASA's Solar Dynamics Observatory, captured one of the most beautiful images in the history of solar astronomy.

The next step, says Smith, is to wait for Solar Minimum. The current solar cycle will wind down in the years ahead, leaving the sun mostly free of sunspots and other magnetic clutter that can obscure nanoflares. NuSTAR will be able to survey the stellar surface and gather data on these explosions like no telescope has done before.

Will it solve the mystery of nanoflares and the solar corona? "I don't know," says Smith, "but I cannot wait to try."

Explore further: Sun sizzles in high-energy X-rays

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7 comments

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thefurlong
3.9 / 5 (7) Mar 20, 2015
@Doug_Huffman
Yes, it might have that effect if you are scientifically illiterate.
DeliriousNeuron
1.5 / 5 (8) Mar 20, 2015
Holy crap! Mainstream physics is more lost than I thought. Nano flares? Really?
First, lets start off with sound physics for normal flaring or basic solar mechanisms.
Just wow!!
Captain Stumpy
4.1 / 5 (9) Mar 20, 2015
LOL No, appending nano- is the same as appending virtual-; it means stop reading now.
@doug
you didn't read up on the prefix Nano before commenting
Nano- (symbol n) is a unit prefix meaning one billionth. Used primarily with the metric system, this prefix denotes a factor of 10−9 or 0.000000001. It is frequently encountered in science and electronics for prefixing units of time and length.
https://en.wikipe...ki/Nano-
So if you have
a type of explosion on the sun called a 'nanoflare.' A billion times less energetic than ordinary flares
then the prefix Nano is accurate and descriptive

just because the most popular usage is about size and QM doesn't mean it is the final definition of the prefix

this is no different than attaching kilo to meter to get a length, or nano to meter, for more appropriate description

so thefurlong is correct in that only the scientifically illiterate or grammatically challenged would consider it thus
cantdrive85
1.5 / 5 (8) Mar 22, 2015
Who'da thunk that Z-pinched plasma or Bennett pinches should be so "mysterious" being they've been studied by real plasma physicists for over 80 years now. Oh right, these are astrophysicists and they prefer their pseudoscientific theoretical mumbo jumbo to real science. They may catch on some day...

Reset,
Your second link is swell and all, but it doesn't explain the electric currents (or Birkeland currents more precisely) that create these events in any way, shape, or form. Try this one instead, it's far more relevant to plasma physics.

http://www.ptep-o...1-13.PDF

You see, it is the Bennett pinch and Peratt instabilities which occurs along these Birkeland currents that cause the "nano" flares, solar flares, supernova, etc...

The real mystery is why astrophysicists choose to ignore real science.

Captain Stumpy
3.7 / 5 (3) Mar 23, 2015
LOL Seaman Stumpy falls victim to the dictionary fallacy.
@Doug_Huffman
Not a seamen... never was
Airman and Soldier, yes
Firefighter, Truck Captain, Gunner... yes
never once was in the Navy or Coast Guard

Now...
how is being intelligent and logical a fallacy?
how is replying on the lexicon and nomenclature of a particular field (especially as it is the one specifically in which we are discussing) a fallacy?
How is utilizing the knowledge or semantics of an entire methodology (as in the naming structure of the metric system) a fallacy?

by all means, feel free to expound upon your post
explain how your choice of words is somehow better than the field experts or the logical definition of Nano

especially detail how we should adhere to mistaken interpretations from a scientifically illiterate group of people who are only exposed to a fraction of the science, and usually screw that up when trying to understand it...
that is important too

Thanks
Captain Stumpy
3.7 / 5 (3) Mar 23, 2015
The real mystery is
@cdTROLL
it is astounding the stupidity which you continue to drivel upon this site
especially when you continue to spout the same blatantly false lies over and over no matter how many times you are proven wrong

this is not just Dunning-Kruger on your part, but a true delusional belief in a faith (eu) as well as the cult like application of hate for anything that debunks your beliefs
be it science or individuals like Thompson
http://www.ploson...tion=PDF
you don't know squat about plasma physics: http://phys.org/n...een.html
also that you can't even read

also proved you lied about astro's not knowing plasma physics
http://science.na...agercme/
you can't find ANY school curriculum for astro's that doesn't include plasma physics

the real mystery is : why are you still lying?
thefurlong
5 / 5 (2) Mar 24, 2015
Yes, it might have that effect if you are scientifically illiterate.
@The Forty Rod Furrow; I commend to you Alan Sokal's 'Transgressing the Boundaries: Towards a Transformative Hermeneutics of Quantum Gravity' to achieve your literacy. It's free on-line and seminal.

Well, if that's what you get your scientific knowledge from, it's understandable that you wouldn't understand what the meaning of "nano" is.
LOL Seaman Stumpy falls victim to the dictionary fallacy.

Why are we having an argument about this? Nano refers to orders of magnitude. A nanoflare would be one that is, in some way, 10^9 times smaller than regular flares.

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