Corona Temperature

[jimmydasaint]

Swansont - why is the temperature of the Sun's surface in the order of thousands of degrees Kelvin, whilst the outer 'layer' and the centre are in the order of millions of degrees Kelvin. I hate to divert a hot thread but it does puzzle the heck out of me?

[csmyth3025]

Swansont - why is the temperature of the Sun's surface in the order of thousands of degrees Kelvin, whilst the outer 'layer' and the centre are in the order of millions of degrees Kelvin. I hate to divert a hot thread but it does puzzle the heck out of me?

The Wikipedia article on the Solar Corona can provide you with a wealth of information. The portion of that article on spicules contains the following:

 

...These observations reveal a one-to-one connection between plasma that is heated to millions of degrees and the spicules that insert this plasma into the corona.

(ref. http://en.wikipedia....s_.28type_II.29 )

 

Chris

[jimmydasaint]

Chris thank you for the explanation provided. I read part of the voluminous article and found the following:

 

Many coronal heating theories have been proposed,[21] but two theories have remained as the most likely candidates, wave heating and magnetic reconnection (or nanoflares).[22] Through most of the past 50 years, neither theory has been able to account for the extreme coronal temperatures. Most solar physicists now believe that some combination of the two theories can probably explain coronal heating, although the details are not yet complete.

 

and

 

The wave heating theory, proposed in 1949 by Evry Schatzman, proposes that waves carry energy from the solar interior to the solar chromosphere and corona. The Sun is made of plasma rather than ordinary gas, so it supports several types of waves analogous to sound waves in air. The most important types of wave are magneto-acoustic waves and Alfvén waves.[23] Magneto-acoustic waves are sound waves that have been modified by the presence of a magnetic field, and Alfvén waves are similar to ULF radio waves that have been modified by interaction with matter in the plasma. Both types of waves can be launched by the turbulence of granulation and super granulation at the solar photosphere, and both types of waves can carry energy for some distance through the solar atmosphere before turning into shock waves that dissipate their energy as heat.

 

and

 

The magnetic reconnection theory relies on the solar magnetic field to induce electric currents in the solar corona.[29] The currents then collapse suddenly, releasing energy as heat and wave energy in the corona. This process is called "reconnection" because of the peculiar way that magnetic fields behave in a plasma (or any electrically conductive fluid such as mercury or seawater). In a plasma, magnetic field lines are normally tied to individual pieces of matter, so that the topology of the magnetic field remains the same: if a particular north and south magnetic pole are connected by a single field line, then even if the plasma is stirred or if the magnets are moved around, that field line will continue to connect those particular poles. The connection is maintained by electric currents that are induced in the plasma. Under certain conditions, the electric currents can collapse, allowing the magnetic field to "reconnect" to other magnetic poles and release heat and wave energy in the process.

 

and

 

For decades, researchers believed spicules could send heat into the corona. However, following observational research in the 1980s, it was found that spicule plasma did not reach coronal temperatures, and so the theory was discounted.

wiki

 

So it seems to be either magneto-acoustic or Alfven waves ( wiki ) carrying heat to the chromosphere and corona. Alternatively, magnetic fields could be broken in the and reconnected under the conditions present in the plasma (ionised gas) of the sun, releasing heat energy. However, it may be a combination of both theories. I don't understand the theory, except in the simple non-specialist words provided, so I will wait for an idiot's guide....

[csmyth3025]

...So it seems to be either magneto-acoustic or Alfven waves ( wiki ) carrying heat to the chromosphere and corona. Alternatively, magnetic fields could be broken in the and reconnected under the conditions present in the plasma (ionised gas) of the sun, releasing heat energy. However, it may be a combination of both theories. I don't understand the theory, except in the simple non-specialist words provided, so I will wait for an idiot's guide....

The sun's coronal heating may be the result of contributions from all of these processes. Sort of like the Earth's weather, there are a lot of things going on in the sun's atmosphere and they all interact in complex ways. Regarding the portion about spicules you referenced:

 

For decades, researchers believed spicules could send heat into the corona. However, following observational research in the 1980s, it was found that spicule plasma did not reach coronal temperatures, and so the theory was discounted.

 

This information has been updated according to a Jan, 2011 Space.com article:

http://www.space.com...lasma-jets.html

 

Chris

 

Edited to insert "Jan, 2011"

Edited April 12, 2011 by csmyth3025

[jimmydasaint]

Nice link there csmyth - and interesting reading. I love the images of the spicules:

 

This information is awesome:

 

Physicists who train their thoughts on the sun have long been perplexed by why its outer atmosphere is millions of degrees hotter than the surface. While theories abound, no direct observations have been made of the mysterious processes that heat the sun's atmosphere … until now.

 

With the help of some state-of-the-art technology, a team of scientists thinks it has discovered an important piece of the puzzle. The results of their new study suggest that the scorching heat of the solar atmosphere is continuously replenished by jets of plasma that scream upward from the surface of the sun at supersonic speeds.

New Info on Spicules

 

Thanks Chris

Edited April 13, 2011 by jimmydasaint

[ecoli]

Personally, I wouldn't drink Corona at any temperature, but probably as cold as possible to numb you tastebuds.

 

Wait, what was the question? ...