Astronomy Picture of the Day -- A Year on the Sun

NASA ^ | April 26, 2013 | (see photo credit)

[SunkenCiv]

Explanation: Our solar system's miasma of incandescent plasma, the Sun may look a little scary here. The picture is a composite of 25 images recorded in extreme ultraviolet light by the orbiting Solar Dynamics Observatory between April 16, 2012 and April 15, 2013. The particular wavelength of light, 171 angstroms, shows emission from highly ionized iron atoms in the solar corona at a characteristic temperatures of about 600,000 kelvins (about 1 million degrees F). Girdling both sides of the equator during the approach to maximum in its 11-year solar cycle, the solar active regions are laced with bright loops and arcs along magnetic field lines. Of course, a more familiar visible light view would show the bright active regions as groups of dark sunspots. Three years of Solar Dynamics Observatory images are compressed into this short video.

[SunkenCiv]

[Credit: NASA, Solar Dynamics Observatory]

[SunkenCiv]

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[SunkenCiv]

the larger one, and it’s big:

http://129.164.179.22/apod/image/1304/743348main_SDOTimelapse_Sun_2k.jpg

[left that other site]

“a miasma of incandescent plasma”...

Poetic! :-)

[null and void]

Hmmm? Isn’t iron a VERY BAD THING for a star?

[Beowulf9]

Okay, I’m not as bright, I’m a little dim...

but “Girdling both sides of the equator...” does this refer to the obvious two ‘equators’ of lighter color there? (I know no way of putting it in intelligent language).

I mean this picture obviously displays two bands of much lighter, and so hotter rings around the sun in what would be about equator areas?

[dragonblustar]

I was thinking that too.

[JoeProBono]

[entropy12]

WOW 1 million degrees on surface! And the sun is expected to put out all that energy for 5 billion more years. Amazing fuel it has!

[Telepathic Intruder]

Only when it starts making its own iron. Then it has one, maybe two weeks left.

[Telepathic Intruder]

Actually the surface is about 5,800 K. It’s in the outer atmosphere that the temperature rises to almost a million degrees. I was confused about that for a time, but the outer atmosphere is rarified gas, and although the atoms absorb enough high-energy light to get that hot, per volume the heat is actually less. Heat conduction is more difficult when atoms are separated, which is why they get hotter individually.

[onyx]

Stunning!!!

[onyx]

Love it!

[SunkenCiv]

Iron is where fission and fusion meet, so, under the current consensus model, yes. :’) Eventually everything winds up iron, and that’s the end of energy production (and life). However, in the meantime, Earth et al is made of iron and other heavier elements produced by stars, and we, uh, need Earth.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1085916/
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1085916/pdf/pnas01852-0022.pdf
http://www.harvardsquarelibrary.org/unitarians/payne2.html

[snip] In a short chapter entitled “The Relative Abundance of the Elements” there is a ticking time bomb. This is the extremely high abundance of hydrogen and helium that had come out under certain assumptions in the analysis. Although we know today that this high abundance is real, at the time it produced an apparent anomaly with respect to the assumed homogeneity of the solar system. After all, when the earth is taken as a whole, it must be predominately iron in order to account for its high mean density, and this is supported by the fact that meteorites are largely iron and by the appearance of the solar spectrum itself, which shows more lines of iron than any other element. The very important principle of uniformity of nature seemed at stake. As Cecilia herself argued in her thesis, “If . . . the earth originated from the surface layers of the sun, the percentage composition of the whole earth should resemble the composition of the solar (and therefore of a typical stellar) atmosphere. . . . Considering the possibility of atomic segregation both in the earth and in the star, it appears likely that the earth’s crust is representative of the stellar atmosphere.” [/snip]

[SunkenCiv]

Those two brighter bands girdle the equator. :’)

[SunkenCiv]

:’)

[SunkenCiv]

http://www.freerepublic.com/tag/olivermanuel/index

http://www.freerepublic.com/tag/oliverkmanuel/index

[null and void]

The problem isn’t so much the mere presence of iron, it’s the absence of any fuel that can make anything lighter than iron.

Unlike making helium (or anything up to iron) making iron absorbs energy. The reaction doesn’t just turn off the central fire, it throws ice-water on it.

Implosion and explosion quickly follow.

Did I get that right?

[Telepathic Intruder]

That's largely correct. The key to understanding it is the nuclear binding energy curve:

which is the excess energy needed to keep an atom stable. Iron represents the bottom of the curve (or the top in this case). Energy is released by combining atoms lighter than iron, and by splitting atoms that are heavier. When a star fuses elements up to iron, no more energy can be attained from fusion. The equilibrium between gravitational collapse and thermal expansion is broken, and the core collapses. This is actually a fascinating event. About as much energy is released in 10 seconds as our sun will produce in its entire 10 billion year life span. And that's from an area only 20 miles across.

[Telepathic Intruder]

Hold on, slight correction. About 100 times as much energy is released in 10 seconds... as our sun will in it’s 10 billion year life span. Not to be overly dramatic or anything...