The surface of the sun is now as hot as the core.

[upriver]

"This evaporated plasma has traditionally been believed to be the source of the hottest temperatures seen in solar flares," said Milligan. "However, the flare in this new observation reached a temperature of almost 27 million degrees Fahrenheit(14 999 982.2 degrees Celsius or 2454eV) -- some nine million degrees hotter than expected for a flare of this size -- without any evidence for beams of accelerated electrons."


The surface of the sun is now as hot as the core.
The solar core is 15 million K.
http://en.wikipedia.org/wiki/Solar_core

[Solar]

Did you mean:

Focused' Solar Explosions Get Hotter

[MGmirkin]

Did you mean:

Focused' Solar Explosions Get Hotter

Most likely. And the implication of that article was that basically there is a combination of two processes that go on in flares. Either there's energy converted into heat, or there's energy converted into charged particle acceleration, or some combination of both. It stands to reason that if one of them doesn't happen, then the other gain the excess energy and ends up with a more energetic process.

IE, if the energy isn't being converted into "heat" (energetic random particle motions), then it's converted into currents of particles flowing in much the same way (non-thermal?)... Or vice versa. If the energy isn't converted into coherent flows of charged particles, it's converted into thermal energy? OR, there's some combination of both. IE, there's both an acceleration of charged particles, and losses to thermal particles.

I hope that makes sense...?

('Focused' Solar Explosions Get Hotter)
http://www.physorg.com/news126358415.html
http://spaceflightnow.com/news/n0804/04solarflare/

"A flare typically divides its energy between directly heating the solar atmosphere and accelerating particles," said Dr. Ryan Milligan of the Oak Ridge Association of Universities, Tennessee, who is stationed at NASA's Goddard Space Flight Center in Greenbelt, Md. "This flare seemed to focus on one task, devoting all its energy to heating, allowing it to become millions of degrees hotter than its multi-tasking cousins." The result will be presented Wednesday, April 2 at the Royal Astronomical Society's National Astronomy Meeting 2008 at Queen's University, Belfast, United Kingdom.

[...]

Flares normally occur above loops of electrically conducting gas, called plasma, in the sun's atmosphere. When a typical flare goes off, it heats the plasma and sends beams of electrons racing down the sides of the loops. The electron beams evaporate more plasma from the sun's visible surface, which expands back up the loops.

"This evaporated plasma has traditionally been believed to be the source of the hottest temperatures seen in solar flares," said Milligan. "However, the flare in this new observation reached a temperature of almost 27 million degrees Fahrenheit -- some nine million degrees hotter than expected for a flare of this size -- without any evidence for beams of accelerated electrons."

[...]

RHESSI revealed that the flare had a peak temperature of 27 million degrees, and also that the flare showed no evidence for high-energy electrons. Hinode was able to show the effects of the energy released at various layers in the solar atmosphere. In particular, the Extreme-ultraviolet Imaging Spectrometer instrument was used to detect signatures of plasma evaporation from the sun's surface through Doppler shifts of emission lines. The low-velocities observed confirmed the RHESSI observation that high-energy electrons were not present.

"If our assumption is correct, then this result tells us that the energy released during a solar flare is more efficient at achieving a higher temperature if the energy is used to directly heat the plasma in the sun's atmosphere, instead of being divided between heating and particle acceleration. This very effect has recently been shown in computer simulations of energy release during microflares," said Milligan.

I don't think they're saying that the entire surface (photosphere / lower chromosphere) is the same temperature as the core / corona. Just that solar flares can get that "hot" in localized regions. Granted, the photosphere / chromosphere are both weakly- to partially-ionized plasma, normally. But it seems that solar flares hop that up a few notches. And when particles aren't being coherently accelerated, they will tend to get very "hot." Whereas when they are accelerated, there may be lower losses to "thermal" particles (random motion, rather than coherent motion?)...

I hope I've read that all correctly, and not gone too wide of the mark? Please correct me if I'm totally off base.

Cheers,
~Michael Gmirkin

[MGmirkin]

I might also direct folks toward Don Scott's page on the Electric Sun. He seems to take a very similar stance to that mentioned by me above in terms of thermalized versus dethermalized charged particles...

(The Electric Sun)
http://www.electric-cosmos.org/sun.htm

Temperature Minimum
Charged particles do not experience external electrostatic forces when they are in the range b to c - within the photosphere. Only random thermal movement occurs due to diffusion. (Temperature is simply the measurement of the violence of such random movement.) This is where the 6,000 K temperature is measured. Positive ions have their maximum electrical potential energy when they are in this photospheric plasma. But their mechanical kinetic energy is relatively low. At a point just to the left of point c, any random movement toward the right (radially outward) that carries a + ion even slightly to the right of point c will result in it being swept away, down the energy hill, toward the right. Such movement of charged particles due to an E-field is called a 'drift current'. This drift current of accelerating positive ions is a constituent of the solar 'wind' (which is a serious misnomer). As positive ions begin to accelerate down the potential energy drop from point c through e, they convert the high (electrical) potential energy they had in the photosphere into kinetic energy - they gain extremely high outward radial velocity and lose side-to-side random motion. Thus, they become 'dethermalized'. In this region, in the upper photosphere and lower chromosphere, the movement of these ions becomes extremely organized (parallel).

The Transition Zone
When these rapidly moving + ions pass point e (leave the chromosphere) they move beyond the radially directed E-field force that has been accelerating them. Because of their high kinetic energy (velocity), any collisions they have at this point (with other ions or with neutral atoms) are violent and create high amplitude random motions, thereby re-thermalizing the plasma to a much greater degree than it was in the photospheric tufts (in the range b to c). This is what is responsible for the high temperature we observe in the lower corona. Ions just to the right of point e are reported to be at temperatures of 1 to 2 million K. Nothing else but exactly this kind of mechanism could be expected from the electric sun (anode tuft - double layer) model. The re-thermalization takes place in a region analogous to the turbulent 'white water' boiling at the bottom of a smooth laminar water slide. In the fusion model no such (water slide) phenomenon exists - and so neither does a simple explanation of the temperature discontinuity.

So, I'm guessing that the stuff mentioned in the thread's topical article is probably right along the lines that the EU / ES model would predict? Assuming solar flares are simply an electrical phenomenon, which should be pretty damned obvious at this point... Heck, we can already see a slow shift in terminology starting: "Flares normally occur above loops of electrically conducting gas, called plasma, in the sun's atmosphere."

('Focused' Solar Explosions Get Hotter)
http://www.physorg.com/news126358415.html

"A flare typically divides its energy between directly heating the solar atmosphere and accelerating particles," said Dr. Ryan Milligan of the Oak Ridge Association of Universities, Tennessee, who is stationed at NASA's Goddard Space Flight Center in Greenbelt, Md. "This flare seemed to focus on one task, devoting all its energy to heating, allowing it to become millions of degrees hotter than its multi-tasking cousins."

So, it seems to me like either a flare engages in accelerating charged particles (current [net motion of charged particles of similar type] in an electric field?) or it thermalizes the particles (bumps up the energy of their random motion [not in the same direction]), or some combination of the two. Conservation of energy seems to make sense here. If one of the processes DOESN'T happen, the other process gets the extra energy!

If coherent acceleration of charged particles dominates, then thermalization doesn't happen as much (lower apparent "temperature"). Whereas if charged particles are not coherently accelerated, then thermalization is the dominant process (higher apparent temperature)?

Cheers,
~Michael Gmirkin