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Tiny
2004-Oct-19, 12:45 AM
Hi there
Just a quick question, what is the color of most of the star&#39;s cores? Earth&#39;s central core is Iron + Metal, therefore it should be like a brown color ball or something... but what about star&#39;s core, the core of our Sun and others? Black hole?

StarLab
2004-Oct-19, 03:39 AM
Nah. Too extreme. White, I&#39;m guessing.

Does a star&#39;s core have the same color as its surface?

antoniseb
2004-Oct-19, 01:42 PM
Originally posted by Tiny@Oct 19 2004, 12:45 AM
what is the color of most of the star&#39;s cores?
If you could see it, the color would be in the x-ray part of the spectrum. To our eye, it would look blue.

TheThorn
2004-Oct-19, 02:12 PM
Colour is determined by the peak wavelength of the light. 700 nanometers is red. 400 nanometers is violet.

The peak wavelength of the light emitted by a hot object is determined by it&#39;s temperature (this is very different than an object that you see by reflected light). The sun&#39;s core is at about 2.3 x 10^7 K, which makes it&#39;s peak wavelength about .13 nanometers (if I&#39;ve done the math right).

That&#39;s in the "hard x-ray" range. Way outside the visible spectrum, way beyond the most extreme ultra-violet.

I don&#39;t think English has a colour for that.

StarLab
2004-Oct-19, 04:37 PM
So we&#39;d "see" a star w/o a core?

antoniseb
2004-Oct-19, 05:56 PM
Originally posted by StarLab@Oct 19 2004, 04:37 PM
So we&#39;d "see" a star w/o a core?
I have no idea how you drew THAT conclusion from anything TheThorn or I wrote. Can you explain your line of logic that got you there, or at least what you mean?

Jim Hampton
2004-Oct-19, 09:10 PM
Hello, Tiny

(I&#39;ve got to find my password - this is ridiculous LOL)

If you&#39;ve seen Mount St. Helen&#39;s picture recently, you&#39;ll notice the color is red, not brown. This is due to the temperature.

Our eyes are sensitive only to a small portion of the electromagnetic spectrum. That portion we call visible light. The temperature of an object will determine a bell curve of radiation emitted by the object, thus its&#39; color.

In the case of a star core, the temperatures will be so extreme that radiation will be most likely in the x-ray portion of the electromagnetic spectrum. Some radiation will, of course, be emitted in the visible portion, but very little of it. If you didn&#39;t get fried by x-rays, it would likely appear blue.

Cores of some stars get very interesting, indeed. Neutron stars have mostly nuclear material at their cores. There would be no way of pulling that material out of the star to observe it as it would explode into ordinary matter (once freed from the tremendous pressures forcing electrons into protons and squeezing out all available space).

Magnatars (try a Google search) would kill you by magnetic force alone, assuming that you weren&#39;t fried by heat, x-rays, and gamma rays. The atoms in your body would be stretched into needle like structures with a diameter 1 % of the length. The length would align with the magnetic force and normal biological processes cannot function.

The long and the short of it is this - when we are dealing with no external light source shining on an object, the perceived color depends upon the temperature of the object and nothing else. Star cores are in the millions of degrees and most of their radiation is shifted *far* above visible light, past ulta-violet.

Best regards from Rochester, NY
Jim

StarLab
2004-Oct-19, 11:29 PM
Well, let&#39;s say a star&#39;s outer layers were see-through...Thornie said the stars "visibility range" was in the x-ray section of the spectra....meaning the core would simply be invisible to human eyes, right?

mikefreeman
2004-Oct-20, 07:28 AM
Originally posted by StarLab@Oct 19 2004, 11:29 PM
Well, let&#39;s say a star&#39;s outer layers were see-through...Thornie said the stars "visibility range" was in the x-ray section of the spectra....meaning the core would simply be invisible to human eyes, right?
On the philosophical aspects of knowledge

Theories are fine. They fit a set of circumstances until an anomoly disproves the theory.

The scientist, biologist, .......ist must strive not just to know or to share the knowledge but to convince himself and others of the certainty of that knowledge

eburacum45
2004-Oct-20, 08:32 AM
No, the core would be far from invisible; but most of the radiation it emitted would be. If the outer layers of the sun were transparent we would see the core shining brightly in the blue part of the spectrum; but the xrays it emitted would also be streaming out towards us invisibly, making it a dangerous sight to behold.

Planetwatcher
2004-Oct-20, 07:52 PM
Well, let&#39;s say a star&#39;s outer layers were see-through...Thornie said the stars "visibility range" was in the x-ray section of the spectra....meaning the core would simply be invisible to human eyes, right?

As one who has to be different, I would think you would see white, not blue.
Why? Because it&#39;s so far beyond the violet end of the color spectrium, and white is the absence of color as far as our perceiption goes.

If it were possible to fly through the Sun and be protected, I believe we would see white in the core, because we can&#39;t perceive the true colors.
However, if our color vision could be expanded to perceive those true colors, then I would think a very bright violet-white would likely be the closest comarison to our current understanding of colors.

So that makes Anton, Jim Hampton, and eburacum45 correct as well.
Sort of. ;)

Tiny
2004-Oct-20, 10:06 PM
Wow, it looks like we have different perspective for disscus the color of core... Once more question : A object such as core when they cool they became dark color (like White Dwarf, when they cool with time, they became dark - below infared), but what happen when a core was born and then light up by fusing elements I mean before the core light up, what color is that core before they can steadily fusing elements? I was thinking about Blackbody...

Chook
2004-Oct-20, 11:39 PM
Quote PlanetWatcher:
"white is the absence of color .."

:blink: Sorry - I thought that WHITE represented a mixture of colours, alternatively BLACK is the absence of reflected/emitted light (and colour). :(

VARN
2004-Oct-21, 01:42 AM
First lets look at a green leaf, now the leaf is not green it is absorbing all the colours except green it is reflecting green. If the outer layer of the sun is transparent there is no light to reflect off of the core therefore it would be black (this is assuming the observer is able to look through an un altered corona i.e. it is still there producing light and cancelling out all other sources).

Planetwatcher
2004-Oct-21, 07:58 PM
Sorry - I thought that WHITE represented a mixture of colours, alternatively BLACK is the absence of reflected/emitted light (and colour). I thought it was opposite. Now your confusing me. :unsure:

Mix all the colors together and you have black. But on the other hand shine a white light at a prisim, and you get a spectrium. Which implies by opposite logic that all colors are in white as well. :huh:

Then there is the issue of black bodies. Which a steller core may be a perfect example of. :o

I think we need to find somebody who knows more then any of us. <_<

Calling Dave Mitsky. Calling Dave Mitsky. :D

Matthew
2004-Oct-23, 01:28 AM
Most of the photon&#39;s in the suns core would be in the x-ray spectrum, with some possibly reaching into gamma rays and some going as low as visable light (and lower). If you looked at a graph of the photon wavelength you would find that it would represent (more or less) a bell graph. With most of the photons being of a specific wavelength (TheThorn has suggested 0.13nm) and the further you get from that wavelenth the less of the photons there would be. Thats more or less the theory, and from which you would say that the core would look white as there would be very little difference between the percentages of blue and red light.

Practical observations suggest white as well. What&#39;s a white dwarf? Its a stars core&#33; We have observed them in space and they are white, admittadly they are not the core&#39;s of an active star, but you get what I am saying (i hope).

TheThorn
2004-Oct-23, 02:51 AM
I&#39;m with you on this one, Matthew. We don&#39;t have a colour for x-ray, but for the part of it we can see, it would probably be white, not blue.

It&#39;s not really a bell curve, it&#39;s skewed (I guess if you put wavelength on a transformed scale of some sort you could make it symetrical, and then it would be a bell). But the key point is that the visible spectrum is so far from the peak that the curve is esentially flat in that range. There&#39;s be a little more blue than red in it, but it would probably look essentially white to our eyes.

Matthew
2004-Oct-23, 03:08 AM
I wasn&#39;t saying that it would be a perfect bell curve (i suppoose i did suggest it) but it the rough outline of the graph.

TheThorn please look at Calculating Wavelength (http://www.universetoday.com/forum/index.php?act=ST&f=13&t=5007) as I believe you may be able to help me out.

Planetwatcher
2004-Oct-24, 03:30 AM
Well, there we have the anwser to Tiny&#39;s question.
A steller core would appear white to us.

I don&#39;t think the type size or color of the star would matter too much, Except for maybe brown dwarfs, and cooled off neutron stars, and even then I couldn&#39;t say.

Now as for black holes, duh, how about black? I think the term black hole would suggest that.

TheThorn
2004-Oct-24, 04:55 AM
Originally posted by matthew@Oct 23 2004, 03:08 AM
I wasn&#39;t saying that it would be a perfect bell curve (i suppoose i did suggest it) but it the rough outline of the graph.

TheThorn please look at Calculating Wavelength (http://www.universetoday.com/forum/index.php?act=ST&f=13&t=5007) as I believe you may be able to help me out.
LOL.