According to the Birkeland model - The sun has a solid surface of iron right below the photosphere. I won't explain everything, but read about it here -- http://www.thesurfaceofthesun.com -- It seems there's evidence from the solar observatories to support this. Discussion!
The surface of the sun.. solid iron?
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Felipi1205
Spaceflight enthusiast
The name of the site makes me remember the movie Sunshine...
Alfastar
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Wait...If the sun is be made of solid iron, then the sun have enough Iron to make a supernova?
Sorry, but I learned that the sun is a star made by Hydrogen and helium. Not from solid Iron.
Sorry, but I learned that the sun is a star made by Hydrogen and helium. Not from solid Iron.
Linguofreak
Well-known member
The sun's photosphere is 5778 K. This is well beyond not only the melting point, but also the boiling point of iron. So there's no chance of any solid iron within the sun.
Furthermore, in objects that are held together by their own gravity, the densest materials tend to sink towards the center. Solid iron has a density of 8000 kg/m^3, whereas the density of the Sun (which we can measure by using visual observations to measure its size and the gravitational dynamics of the solar system to measure its mass) is 1400 kg/m^3. If there is a layer of solid iron within the sun, everything within that layer will almost certainly have a density greater than or equal to that of iron, which, with their claim that the iron layer begins immediately below the photosphere, would imply that the sun has a density five or six times higher than its mass and observed size allow for.
Furthermore, in objects that are held together by their own gravity, the densest materials tend to sink towards the center. Solid iron has a density of 8000 kg/m^3, whereas the density of the Sun (which we can measure by using visual observations to measure its size and the gravitational dynamics of the solar system to measure its mass) is 1400 kg/m^3. If there is a layer of solid iron within the sun, everything within that layer will almost certainly have a density greater than or equal to that of iron, which, with their claim that the iron layer begins immediately below the photosphere, would imply that the sun has a density five or six times higher than its mass and observed size allow for.
Frogisis
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Yeah that's crazy. I'm definitely skeptical of any layers of iron in the sun.
Slightly off topic, but I've never been able to find a good answer to this: What's the consistency of the surface of a star like our sun? I asked my high school physics teacher this one day, wondering if it'd be like a mist that gradually gets denser, and he said the gravity is so high it might compress it into something a little closer to a liquid, but he didn't know. It roils so violently it might not even be a sensible question, but I've never found an answer to what it would feel like to stick your (heat-invulnerable) hand into the sun, assuming you could stay stationary relative to a patch of surface.
In photos it looks kind of like a discrete surface of boiling liquid (without the bubbles), and nature loves that self-similarity with textures like that so presumably it looks similar on smaller and smaller scales, but that's got to break down at some point.
Slightly off topic, but I've never been able to find a good answer to this: What's the consistency of the surface of a star like our sun? I asked my high school physics teacher this one day, wondering if it'd be like a mist that gradually gets denser, and he said the gravity is so high it might compress it into something a little closer to a liquid, but he didn't know. It roils so violently it might not even be a sensible question, but I've never found an answer to what it would feel like to stick your (heat-invulnerable) hand into the sun, assuming you could stay stationary relative to a patch of surface.
In photos it looks kind of like a discrete surface of boiling liquid (without the bubbles), and nature loves that self-similarity with textures like that so presumably it looks similar on smaller and smaller scales, but that's got to break down at some point.
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N_Molson
Addon Developer
A star like the Sun produces Iron only in its terminal phase, when there are no more lighter elements to feed the nuclear reaction. In fact Iron is the heaviest element that a star can produce ; dead stars are ultra-dense, almost pure balls of Iron.
RisingFury
OBSP developer
You don't need to believe anything and everything you see on the net. Just some basic understanding of Chemistry and Physics will allow you to figure out how much bull.... that statement is.
Izack
Non sequitur
There's evidence supporting any theory a person can find inside his rectum if he presents it in the right light to the right sort of people, and conveniently neglects to mention the planet-sized mass of contradictions behind it. :2cents:
RisingFury
OBSP developer
That depends on the type of death a star suffers.
If the star is low mass, after it expands into a giant, it can blow away its atmosphere. The core would remain - a white dwarf. Not all stars can reach temperatures capable of fusing iron. Many of them are composed of mainly Carbon and Oxygen and can maintain fusion of hot enough.
In such a star, the main component of pressure is provided by electron pressure.
If the star gains mass (through accretion), the electrons would need to move faster than the speed of light to hold up against gravity. Since that's impossible, the star collapses. That happens at 1.38 solar masses (Chandrasekhar limit) and results in a type Ia supernova.
Since this always happens at approximately 1.38 solar masses and all white dwarfs have approximately the same density, the energy released in this type of supernova is always approximately the same - they gained a nickname "standard candle".
In the collapse, protons and electrons can fuse, creating neutrons. After the collapse, the more heavy neutrons can provide sufficient pressure to hold the star up against gravity. Since they're heavier, they can move at slower speeds to provide enough pressure.
For a collapse of a neutron star into a black hole, the estimate is given as 3 to 4 solar masses, however, no neutron star heavier than 2 solar masses has so far been found.
Just wanted to set things straight...
jimblah
New member
Nuclear chemistry isn't my strong suit..
I'm under the impression that iron can't fuse and that heavier elements are created during the process of the type 1A event...
I'm under the impression that iron can't fuse and that heavier elements are created during the process of the type 1A event...
Urwumpe
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Exactly. And the sun can in fact produce small amounts of iron during everyday processes. But not much and most of this iron will accumulate in the center of the sun, only traces should even be able to get out of the radiation zone. There should be no condition in which gaseous iron will accumulate near the photosphere (too high density, not even ferro-magnetism), and especially, as said above, not solid iron. The pressure is too low and the temperature too high, there would only place for ions.
RisingFury
OBSP developer
Very, very, very little iron fusion goes on in the Sun right now. To fuse iron, temperatures have to be in the range of several hundred million Kelvin. Right now they're about 15 million Kelvin.
The rate of iron fusion in the sun is possibly comparable to the rate of hydrogen fusion at room temperature. If you wait long enough, you'll see one fusion reaction...
Vast majority of Iron and other non-Hydrogen, non-Helium elements (generally referred to as metals in Astrophysics) are there because the Sun came relatively late after the formation of the universe.
The Big Bang cooked up approximately 25% of Helium and some trace amounts of metals. The early stars therefore contained only trace amounts of metals. But as the universe aged and more stars kept fusing heavier elements, they enriched their surroundings with metals. When our Sun formed, it formed from the enriched material that contained these metals created by previous generations of stars...
Also, you mentioned ferromagnetism in iron... I don't know if iron remains ferromagnetic at such high temperatures. Keep in mind that ferromagnetism is caused by the spin of electronsm and their charge, which results in a magnetic dipole, but at high temperatures as we find in stars, pretty much all atoms are highly ionized. The electrons get stripped away from the atom, so the ferromagnetic properties would probably disappear. I don't know this for a fact, though. I imagine that would happen...
Urwumpe
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That isn't exactly like cooking though. The iron production rate requires some temperatures to reach maximum, but even at lower temperatures there is a chance for it to be produced. It is a very low chance, but the sun takes a few billion attempts per nanoseconds.
---------- Post added at 01:49 PM ---------- Previous post was at 01:45 PM ----------
You misunderstand me there: I excluded it. It requires cold solids anyway.
And iron ions aren't really that mobile compared to lighter ions.
jedidia
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Not quite. It can fuse, but due to some reason, its fusion consumes energy instead of releasing it.
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That much iron? Uh... doesn't that mean we're in rather big trouble...
Where's our resident "We're all gonna die
" poster?
:lol:
Where's our resident "We're all gonna die
" poster?:lol:
martins
Orbiter Founder
tblaxland
O-F Administrator
A good description of the what, but not the why
. As I understand it, at low atomic weights the binding energy increases with the number of nucleons due to the increased cumulative strong nuclear force between them. Above a maximum binding energy point, the binding energy decreases with the number of nucleons as the cumulative Coulomb (electrostatic) force between the protons becomes more dominant. More detailed explanation here: http://physics.stackexchange.com/questions/961/why-is-the-nucleus-of-an-iron-atom-so-stableTommy
Well-known member
I can tell you from experience that if you heat iron or steel up with a torch until it's at least "bright orange" (the point where it starts to plasticize), a magnet will no longer stick to it. From this, it seems that ferromagnetism does break down, and at much lower temperatures than the Sun.
However, the intense pressures of the Sun may change this, the same as it would the boiling point of Iron.
RisingFury
OBSP developer
I am aware of that effect. The temperature that happens at is called Curie temperature. But there is a difference when you're talking about a single atom or a large mass.
The reason heated material loses its ferromagnetic properties is because the energy of atoms inside the crystal increases with temperature. The magnetic domains can no longer grow large.
Ferromagnetic properties come from the spins of electrons as I mentioned in an earlier post. In a large mass, the spins cause magnetic field and that forces the neighboring spins to orient in the same direction, amplifying the magnetic field. But as you increase the energy of atoms, they jump around too much for the spins to stay aligned.
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