Iron Sun Surface Thermodynamically Impossible VI
Dude!!I see an image of light emitted from material at a temperature of 500,000K to 2,000,000K. That is the quite basic physics involved in taking these images. A passband that only detects light from material at a certain temperature .... only detects light from material at the temperature
!
Or it will detect 192/5A light from reflections off of solid material at a lower temperature. Like the mirror in TRACE'S telescope.
That mirror is no where near 1 million degrees. Same with the solar surface.
Basic physics.
So if the surface did exist then there is no problem with the reflection part.
Well, now, let's talk about basic physics and see if there really is "no problem".
First, what about "
just like the mirror in TRACE'S telescope". The mirrors in TRACE, like any other astronomical mirror, are highly polished to enhance reflectivity. Is the "surface" of the sun (whatever it might be made of) highly polished? Unlikely, I think. And in the case of TRACE, the primary mirror is coated with special, normal incidence coatings that further enhance reflectivity at UV & EUV wavelengths, and to narrow the passband. Are there any reflectivity enhancing coatings on the surface of the sun? I think that too is unlikely.
Next, let's ask what this reflective surface is made of. In keeping with the primary consideration of this thread, let's just assume the surface is iron (or at least mostly iron). I don't know how iron reflects EUV wavelengths, but in a moment I will guess. Meanwhile, I do know that iron reflects visible light about 62% at the red end (7000Å) down to 52% at the blue end (4000Å). If we simply assume a linear trend to shorter wavelengths, we would get about 35% reflectivity around 192Å or 195Å. But that does assume a specular surface and we know that dispersion off of a non-specular surface will degrade the reflectivity, so 35% would be a best-case scenario guess.
But here comes that basic physics. Photons that ionize iron don't reflect off of an iron surface, they ionize it and disappear in the process. Likewise, photons that carry enough energy to melt iron don't reflect off of an iron surface, they melt it and disappear in the process. The 192/5Å passband represents Fe XII (11-times ionized iron). So we would expect photons at that wavelength to preferentially not reflect off of an iron surface, but rather to ionize it. Furthermore, the 192/5Å passband represents the peak of thermal emission in the broad range of temperatures 500,000 - 2,000,000 Kelvins. Since the melting point of iron is 1811 Kelvins, and its boiling point is 3134 Kelvins, we would expect photons in the 192/5Å passband to melt & vaporize the iron surface and disappear in the process, and not to reflect off of the surface.
So, why does the mirror on TRACE not melt in the face of melting photons in the 192/5Å passband? It's all about
intensity. The TRACE mirror has to deal with a few photons. One at a time, we don't necessarily expect the photons to ionize or melt anything (although the coatings are intended in part to prevent degradation of the primary mirror). But when photons gang up on a surface, they can and will provide enough thermal energy to melt & vaporize that surface, and then ionize the resulting vapor. Here at Earth, where we find TRACE, the incident solar EUV flux will be about 2 erg cm
-2 sec
-1, whereas at the sun we are looking at roughly 600,000 erg cm
-2 sec
-1 (which will be much higher near active regions). And do note this is EUV flux only, the bolometric flux at the photosphere is about 60,000,000,000 erg cm
-2 sec
-1. That's a lot of photons, and we cannot simply pretend that any solid surface is immune to the effect of that kind of photon bath.
So basic physics presents a problem after all. No, TRACE should not see any photons in the 192/5Å passband reflecting off of any iron surface. Rather, all of those photons should disappear in the process of melting, vaporizing and ionizing that surface. Furthermore, a little consideration shows that this should be the case no matter what the surface is made out of, since the temperature range 500,000 - 2,000,000 Kelvins vastly exceeds the boiling point of all known materials. So photons of the 192/5Å passband should not reflect off of any surface on the sun, regardless of its chemical/physical makeup.
We will get to the thermodynamic considerations.
It is your contention using your photosphere model that not enough energy escapes to allow a solid iron surface to exist under "your photosphere model". And I'm sure your model requires complete coverage of the lower surface to achieve your goals(molten iron/plasma).
You may be sure, but you are still wrong. The only thing required is that enough incident radiation falls on the surface to prevent it from being solid, and that radiation can come from any direction. So ever if the hot stuff is "way over there", if it covers a sufficient fraction of the sky, it will melt the surface.
It is my contention that enough energy escapes from under the surface glow to allow a solid surface to exist in my surface glow model.
Earth's atmosphere emits rather less radiation upwards than it does downwards, because the upper layers are cooler then the lower layers (the average annual Earth surface temperature is 288 Kelvins, but the radiative temperature of the top of the atmosphere is 254 Kelvins). We know from limb observations of the sun that, as deep as we can make direct measurements, the solar plasma is warmer at the bottom than at the top; the photosphere, to the extent that we can see it, reaches almost 10,000 Kelvins at the bottom, which is already well in excess of the vaporizing temperature of iron. So, as is the case for Earth, the photosphere of the sun is brighter & hotter at the bottom than at the top.
No spontaneous thermal process can cool the surface under that plasma to a temperature cooler than the plasma without violating the 2nd law of thermodynamics. You need a non-thermal heat pump (like a refrigerator) to pull that off. So what is the non-thrmal heat pump that you hypothesize as a "cooling mechanism" for your iron surface?
