It's hot... super hot: Finding answers around the sun

Nov 13, 2013 by Ivy F. Kupec
By analyzing satellite data, the researchers could study the coronal heating problem specifically around a polar coronal hole. Credit: Michael Hahn and Daniel Wolf Savin, Columbia University

(Phys.org) —Astronomers have collectively puzzled over two working theories for a conundrum involving the sun that have been discussed in Astronomy 101 classes for decades: Why is the sun's corona (the atmosphere beyond the sun) so hot? The sun's core is a searing 15 million degrees Kelvin, but by the time that heat reaches the sun's surface, it cools off to a mere 6,000 degrees, only to again heat up to more than a million degrees in the corona.

Two researchers at Columbia University recently published what they believe is the solution, and it has to do with magnetic waves known as Alfven waves. The researchers present their findings today at the Hinode 7 Science Meeting in Japan.

Michael Hahn and Daniel Wolf Savin analyzed data from the Extreme Ultraviolet Imaging Spectrometer on the Japanese satellite Hinode over a polar coronal hole and found that, much like the vibrations of a plucked guitar string, the lines also pulsate, and in doing so transfer energy from below the sun's surface into the corona. Hinode's spectrometer captured the waves penetrating the upper solar atmosphere.

"This is a fundamentally important finding," said Ilia Roussev, NSF program director for solar terrestrial research. "This issue is the holy grail of solar physics. If this allows us to better understand the mechanics, then it has tremendous consequences."

The coronal heating problem has been debated for 70 years with researchers essentially falling into two camps: one involving the Alfven waves and the other attributing the heating "problem" to magnetic field loops that stretch across the solar surface with the potential to "snap" and release energy. The important key to Hahn and Savin's findings comes with Hinode satellite observations. The team has been studying Hinode data since 2009 with funding since 2011 from the NSF Solar, Heliospheric and INterplanetary Environment (SHINE) Program.

"This is the big, unanswered question in , and nearly everyone in the field is somehow working on trying to solve it," Savin said. "We really had no idea where the research would lead us, but we were hoping to at least be able to add another piece to the puzzle. We did not expect it to be such a big piece."

In fact, technology had to catch up to theory to make this happen. The Hinode satellite, a Japanese mission with the Extreme Ultraviolet Imaging Spectrometer developed as collaboration between Japan, the United Kingdom and the United States, offered unique, previously unattainable observations.

"Until that time, we could only see the sun in white light; we didn't have UV observations. But, now we do," Roussev noted. With the UV capability, researchers can glean information on chemical makeup and physical conditions near the sun's surface that until the mid-1990s could not be observed. Hinode has been studying the sun since 2006.

"Some in the community have responded enthusiastically to our findings; others more cautiously, but that is to be expected," Savin said. "Others, including us, have pointed out that there may not be just one solution to the problem as there are different structures on the Sun. Our work is relevant for coronal holes, which are the source of the fast solar wind. A different mechanism or mechanisms may be operating in the quiet sun."

The "ins and outs" of Earth's atmosphere

While the sun is almost 93 million miles from earth, the electrons and protons from the sun move toward Earth via a wind of particles. This solar wind has impacts on the Earth's atmosphere in locations where satellites provide important imagery of our planet and allow technology like GPS and cell phones to operate.

"Ultimately, this kind of research does provide new perspective on space weather, which is known to affect the Earth" said Hahn, who was awarded a 2012 Blavatnik Award for Young Scientists by the New York Academy of Sciences for his work on the coronal heating problem. "Understanding these fundamental processes improves our understanding, of not just the solar corona, but also of space weather."

Specifically, the high temperature of the sun's corona causes it to emit X-rays that can affect the conditions of Earth's atmosphere where satellites roam. "The is the biggest X-ray machine in the solar system," Roussev explained. "The upper layers of earth's atmosphere absorb those X-rays, but what they do is heat that upper atmosphere. It expands almost like the Earth breathing in and out. This has a direct impact on the lifetime of satellites. The more the atmosphere expands, the slower the satellites move. That shortens their lifetime as they slow to a point where they re-enter the atmosphere."

Puzzle solved. Now what?

The interesting thing about potentially solving a puzzle like this one is that the solution raises more questions.

"What causes Alfven waves to be damped at such surprisingly low heights in the corona?" Savin asked, who is now proposing a series of experiments in plasma physics to simulate conditions in a coronal hole and explore possible mechanisms that would cause the waves to lose their energy. "We are also analyzing Hinode observations of other solar structures in the corona to see what role waves play in heating those structures."

Other researchers will likely explore replication, especially involving observations elsewhere in the corona, rather than just polar coronal holes.

"People have been claiming to solve the coronal heating problem for decades," Hahn said. "We are reasonably confident in our results and wait now for others to reproduce our findings."

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User comments : 18

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billhd
1.3 / 5 (12) Nov 13, 2013
A field line cannot snap. It is a nonphysical entity, comprising the calculation or measurement of a field value along a path. It is by definition smooth and continuously differentiable, which means it cannot have a discontinuity.

If a field line pulsates it is because there is an amplitude pulsation of something physical, like matter density.
baudrunner
1 / 5 (12) Nov 13, 2013
The current paradigm - that the sun is a giant gas ball - needs to be addressed. If the surface of the sun were essentially solid, such as is the case with an iron mantle (iron has maintained solid state in the lab at temperatures exceeding those on the surface of the sun) then that represents a state of confined energy. The neon plasma outer layers of the sun's ionosphere represents the first stage of the release of extreme electrical energies. Temperatures are shown to be greater in that layer then they are on the surface. Maximum release of energies is represented within coronal loop patterning formed by electrical arcing, and therefore maximum temperatures are measured there. There is plenty of evidence to support the sun's iron mantle hypothesis, not the least of which are maintenance of the structural integrity over elapsed time frames, of "cratering" on the surface,
Q-Star
3.7 / 5 (3) Nov 13, 2013
There is plenty of evidence to support the sun's iron mantle hypothesis, not the least of which are maintenance of the structural integrity over elapsed time frames, of "cratering" on the surface,


Plenty of evidence?

Yeppers the iron lines in the spectra (< 0.001 %) are pretty good evidence. Oh, and the mass/density of the sun,,,, that's good evidence of the iron theory. Oops, I almost forgot, the explanation for where all iron came from,,,, that is good evidence too. Ya might be on to something,,, maybe ya should get together with Oliver Manuel and collaborate on a paper (but leave your children, if have any, at home while ya are off working on it.)
antialias_physorg
3.7 / 5 (3) Nov 13, 2013
A field line cannot snap.

When the field along a (former) field line reaches zero and the gradients diverge shortly afterwards the line has effectively 'snapped' into two (or more). If the gradient doesn't diverge it may just have reversed direction.
It is by definition smooth and continuously differentiable,

But not necessarily monotonous. See above. There is no discontinuity needed for a field line to 'snap'.
Pressure2
1 / 5 (11) Nov 13, 2013
I certainly do not know if this is a reasonable explanation, but since the sun's corona is a plasma it should be able to absorb the higher frequencies, such as x-rays and gamma rays, radiated from the sun's surface. This could be the source of the extremely high temperatures of the corona. The corona may be shielding the earth from most of the sun's harmful high frequency radiation by absorbing it.
cantdrive85
1 / 5 (16) Nov 13, 2013
"Magnetic reconnection is pseudo-science." Hannes Alfven

There is either a magnetic field or not, there is no "field line" in any way shape or form. We humans are pretty stupid, so to "visualize" this invisible field at a given time or place we use mathematics and draw lines to help. Some have chosen to reify these mathematical constructs into real entities, completely ignoring Alfven and others for decades.

"A magnetic field line is by definition a line which is everywhere parallel to the magnetic field. If the current system changes, the shape of the magnetic field line changes but it is meaningless to speak about a translational movement of magnetic field lines." - Alfvén

Note in that comment; "If the current system changes". Alfven understood electricity is the cause of the magnetic field, if you read above there is no mention of currents. Just magnetic loops, snapping field lines, x-rays caused by heat, and any number of other misrepresentations of plasma phenomena.
barakn
5 / 5 (2) Nov 13, 2013
We all can see what's going on here. Your derision of a mathematical tool is rooted in deep shame stemming from your mathematical illiteracy.
cantdrive85
1 / 5 (14) Nov 13, 2013
We all can see what's going on here. Your derision of a mathematical tool is rooted in deep shame stemming from your mathematical illiteracy.

My derision is directed toward those who can't see the difference between a tool and what is real. It's rather apparent there is a tool present though.
Protoplasmix
1 / 5 (12) Nov 14, 2013
We are reasonably confident in our results and wait now for others to reproduce our findings

Looks more like the confidence is in interpretations of observations and there is the hope others will concur with those interpretations. Among the many types of structures on the surface, those at the poles are quite unique, certainly with regard to observations of A-waves at all, much less addressing conditions conducive to their formation. It's hard to believe there's any heating of the corona whatsoever by A-waves propagating through a hole in it.
baudrunner
1 / 5 (9) Nov 14, 2013
@Q-Star..

It'll take you the better part of an evening to garner all the information contained in the following link. It is a very well researched paper on just this subject, and references data from many sources, like SOHO and TRACE.

From the home page at http://www.thesur...sun.com/
There are a whole host of unexplained phenomena related to the sun's activities that still baffle gas model theorists to this day because they fail to recognize the existence of an iron alloy transitional layer that rests beneath the visible photosphere. Fortunately a host of new satellites and the field of heliosiesmology are starting to shed new light on this mysterious "stratification subsurface" layer of the sun that is located about 4800km beneath the visible photosphere.


Q-Star
5 / 5 (1) Nov 14, 2013
@Q-Star..

It'll take you the better part of an evening to garner all the information contained in the following link.


Took only three minutes to read it. But maybe I'm especially talented in the reading department. Nothing in it was compelling in the least. But if ya like it, carry on with it. Ya are the best judge of the use of your time.
baudrunner
1 / 5 (2) Nov 25, 2013
Q-Star: you didn't read all of the site's content. Like I said, it would take you the better part of an evening to garner all of the information contained therein. If you don't take that data seriously, because it comes form the instruments sent up there to examine and analyze the sun, then we can all cease to take you seriously.
Q-Star
not rated yet Nov 25, 2013
Q-Star: you didn't read all of the site's content. Like I said, it would take you the better part of an evening to garner all of the information contained therein. If you don't take that data seriously, because it comes form the instruments sent up there to examine and analyze the sun, then we can all cease to take you seriously.


I don't care how ya take me. It took me only a few minutes to read the article. At the bottom it had a link for Contact For Further Information,,, it was for emailing the author. I didn't find that he has a site to peruse, just the one article ya linked to, unsigned I might add. I did not find his arguments compelling. I can site hundreds of books and papers and apply them out of context to promote my theory of the unicorn. But that doesn't mean any of the authors of the papers endorses my theory of unicorn. Maybe ya could get can'tdrive or HannesAlfven interested, they think all theories are created equal and every world view is correct.
Simca
Nov 25, 2013
This comment has been removed by a moderator.
NOM
not rated yet Nov 25, 2013
My previous comment was deleted from here
As should all your comments troll.
Simca
Nov 25, 2013
This comment has been removed by a moderator.
NOM
not rated yet Nov 25, 2013
And yet you have managed to get at least 12 accounts banned from this site.
Simca
Nov 25, 2013
This comment has been removed by a moderator.
Simca
Nov 25, 2013
This comment has been removed by a moderator.
Simca
Nov 25, 2013
This comment has been removed by a moderator.
Simca
Nov 26, 2013
This comment has been removed by a moderator.
NOM
Nov 26, 2013
This comment has been removed by a moderator.
Q-Star
Nov 26, 2013
This comment has been removed by a moderator.
NOM
5 / 5 (1) Nov 26, 2013
My next pick would be the ratings troll, Noumenon, and his 50 sockpuppets.
Q-Star
5 / 5 (2) Nov 26, 2013
My next pick would be the ratings troll, Noumenon, and his 50 sockpuppets.


He's the one who is always complaining about ratings trolls? Hmm, maybe so, but the HannesAlfven nutter is so very tiresome with his endless streams of "unoriginal" rants against unoriginal scientists. I don't think he has ever spoken in his own words, just snip and glue from the same four or five disgruntled people. He's mostly just mad because no one would acknowledge his genius and wouldn't help him in his delusions of greatness. In other words, he couldn't cut it in a science program. So now he annoys for payback and to get even. He doesn't believe all that silly stuff he posts, he uses it as a weapon.
NOM
not rated yet Nov 27, 2013
You are quite right about HannesAlfven and his minion cantthink85.

Noumenon doesn't like other people exercising their right to vote on people's posts. So he has at least 50 sockpuppet accounts purely for upvoting himself. He usually only does this on older threads in the belief that noone will catch him at it. He has occasionally used his sockpuppet army to downvote posters, such as FrankHerbert.
The fact that members such as toot chose to interact with the voting button rather than posting doesn't make them a "ratings troll", unnless they have multiple accounts for this purpose - as does Noumenon.