View Full Version : Questions about degenerate matter

2003-Jun-16, 09:00 PM
Degenerate matter, also known as white-dwarf matter, is formed when pressure (NOT gravity! - see "Question about Neutron Stars" thread) crushes the atoms' electron shells. The resulting mix of electrons and nuclei is supported by Pauli exclusion pressure of electrons, which does not depend on temperature. Consequently, unlike "normal" plasma, degenerate matter can be quite cold.

My questions are:

1. Different electron shells within an atom take different (sometimes VERY different) amounts of energy to remove. White dwarves are a mix of elements from hydrogen to iron. Is it possible that at some specific pressure value, i.e. particular depth from white dwarf's surface, the outermost electron shell will be crushed, but the others will remain intact?

2. Normally those inner shells do not participate in chemical reactions. If exposed by the pressure as described above, will they do so?

3. Some elements have much lower first ionization energy than others - alkali metals have the lowest of all. Can relatively "modest" pressure - say the kind at the center of Earth, - force the lone electron in say, potassium's outer shell into degenerate state? My guess is that under such conditions potassium would act as a noble gas - totally disinterested in chemical activity, - because all its remaining electron shells are full.

2003-Jun-16, 11:32 PM
Boy! This a deep set of questions. I think you'll need the likes of TBA, Tim Thompson or Spaceman Spiff. Put the word out BABBer's, we need the big guns. :)

Tim Thompson
2003-Jun-17, 12:38 AM

I don't see how that could be possible. It's like asking if you can fill a bottle with gas, so the top half is low pressure and the bottom half is high pressure. But it just doesn't happen, the whole gas bottle has just one pressure (assuming the bottle is "small", and unlike Earth's atmosphere, which does have a higher pressure at the bottom).. Likewise, the "electron gas" orbiting the nucleus has just one pressure. It's either degenerate, or it isn't, but it can't be partly degenerate.


The inner shells can be exposed by ionization, but not by pressure.


This looks like question #1 slightly altered. The outer shell cannot be degenerate without all of the other shells being likewise degenerate. Ionization potential only tells you how much energy it takes to remove the electron from the atom. But squeezing the electron into the electrons below it is a horse of a different color.

2003-Jun-17, 01:45 AM
White dwarves are a mix of elements from hydrogen to iron.
<nomenclature nitpack>

The plural of white dwarf is "white dwarfs." The alternate pluralization of dwarf as "dwarves" didn't come about until Tolkien write The Hobbit in the 1930s. (Look at the full title of Disney's Snow White if you don't believe me.) All of the mentions of dwarf stars in the Astro literature -- whether white dwarf, red dwarf, brown dwarf, black dwarf, or main-sequence star -- pluralize the word as "dwarfs."

</nomenclature nitpack>

2003-Jun-17, 03:53 AM
Thank you, Tim. Back in the Soviet Union in 1970's I read a chemistry book which described all of the above: pressure forcing outer electrons into degenerate state but not others, weird chemistry which results from that, and that the pressure in Earth's core is sufficient to force alkali metals (and perhaps other low-ionization-energy elements) into that state. I guess the only thing degenerate was the author's brain!