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B Mass of Sun/stars (elemental/molecular vs. plasma)

  1. Dec 6, 2016 #1
    I'm confused about the mass of the Sun (and stars in general).
    Wikipedia notes:
    " It is a nearly perfect sphere of hot plasma..."
    ...and later ...
    "About three quarters of the Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%), ..."

    I thought that plasma was not comprised of elements (much less molecules); rather, it's a soup of particles in that fourth state of matter.
    Correct me if I'm off, of course.
    So how can the Sun be mostly H/He (mass) and hot plasma?
    I asked the above on another forum, and a reply was:

    "The atomic nuclei retain their identities, which is what gives the elemental abundances quoted."

    To which I replied:
    Wiki also notes:
    "In a plasma, electrons are ripped away from their nuclei, forming an electron "sea". This gives it the ability to conduct electricity."
    I can buy that ...except the fact that (for H, 75% of Sun's mass) you've got single protons floatin' 'round in a sea of electrons. Not sure what nuclear identities can be made out from that confused mess, unless you're further dividing the proton's HYDROGEN identity to its quark-based substructure.
    To which another member replied:
    "The nuclear identity of a proton is simply "hydrogen". No need to bring quarks into it, an isolated proton and a hydrogen nucleus are just the same thing."
    So what is plasma in the Sun? E.g., ist it simply 75% Hydrogen as free-floating protons in a sea of electrons ... followed by 2P/2N nuclei in that same sea of electrons ... etc.?

    If I have single protons in a sea of electrons (but not in orbit around the proton), is that configuration elemental hydrogen?

  2. jcsd
  3. Dec 6, 2016 #2


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    Plasma IS comprised of elements - specifically their bare nuclei + electrons. Those are the particles making up the soup.
    Yes. It's hydrogen plasma.
  4. Dec 6, 2016 #3
    I think Wiki (and other physics references) should use compound phrases like "hydrogen plasma" and/or be more clear when it comes to defining the elemental phases of matter.
  5. Dec 6, 2016 #4


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    Wikipedia is not a physics reference.
  6. Dec 7, 2016 #5


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    Why? "Solid" is a state of matter, you don't have to list "iron solid, sodium solid, chromium solid, gold solid, ...". You can talk about solid gold if you want to look at this element in particular, but that is not the general concept of a solid any more - it is more specific. Same for plasma: You can make many general statements about plasma, but if you want to look at one particular instance (like the sun) you can be more specific: "hydrogen/helium plasma".
  7. Dec 7, 2016 #6
    Is plasma, like hydrogen plasma in the Sun, ionized? Ionized by one of the word's definitions (i.e., loss of an electron)?
  8. Dec 7, 2016 #7


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    The atoms in a plasma are ionized - at least enough of them to have many electrons and ions. That is the definition of a plasma.
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