Recent content by MarkL

  1. M

    I Integrating discs to find the gravitational force of a sphere

    If anyone is interested... The equation for the ellipse is ## x^2/a^2 + y^2/b^2 = 1##, ##a > b##. Substituting ##a## for ##d## above and solving for ##y##, the equations become \begin{align*} & 2\pi Gm\sigma \int_{-a}^{a}[1 - \frac{(a-x)}{\sqrt{(b^2-(b^2/a^2)x^2)+(a-x)^2}}]dx \\ \text{or} \\ &...
  2. M

    I What Prevents Electrons from Expanding Radially in White Dwarfs?

    Your last paragraph would never influence an electron with enough pressure to support the mass of a star. Your first paragraph, however, is spot on and intuitive. And I'm good...thanks for your response.
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    I What Prevents Electrons from Expanding Radially in White Dwarfs?

    the answer above was: "restoring force bringing back neutrality" Does this mean, bring back (to neutrality) = zero electron expansion or prevents electron expansion or expand till (neutrality) = electrons expand till force equals fermi pressure = some electron expansion
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    I What Prevents Electrons from Expanding Radially in White Dwarfs?

    bring back...or expand till
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    I What Prevents Electrons from Expanding Radially in White Dwarfs?

    From Wikipedia : White dwarfs resist gravitational collapse primarily through electron degeneracy pressure What prevents electrons from expanding radially through the space between the ions (carbon, say)?
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    B Coulomb pressure and concentric spheres

    Suppose you have a sphere of radius a of positive charge, and a concentric shell from a to b of negative charge. The positive charge is equal to the negative charge. (non-conducting, uniform density) Is there an outward pressure at a of kqq/a2/(4πa2) - with pressure decreasing with radius...
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    Stargazing Understanding the Chandrasekhar Mass Units for Relativistic Lane Emden Equations

    I guess I can't delete...
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    Stargazing Understanding the Chandrasekhar Mass Units for Relativistic Lane Emden Equations

    a is in Lame Emden equations --- as in, r = a ξ
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    Stargazing Understanding the Chandrasekhar Mass Units for Relativistic Lane Emden Equations

    Thank you - I discovered my mistake. I will delete this post shortly.
  10. M

    Stargazing Understanding the Chandrasekhar Mass Units for Relativistic Lane Emden Equations

    Using Lane Emden and n = 3 (relativistic), I calculate the correct mass -- the Chandrasekhar mass (about 1.4 Msun) The equation goes Mtotal ∝ a3, because at n=3, the density, ρ, cancels out. a2 ∝ K/G = Kg2 → a3 ∝ Kg3. Here K ∝ h c or Kg m3/sec2 and G ∝ m3/Kg/sec2 This implies the mass, Mtotal...
  11. M

    I Why does Webb orbit L2, is it because of the Moon?

    Why not place it on the moon?
  12. M

    I What happens to the material not involved in the core collapse of a supernova?

    supernova remnant...duh! https://en.wikipedia.org/wiki/SN_1987A looks more controlled...like a smoke ring thanks
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    I What happens to the material not involved in the core collapse of a supernova?

  14. M

    I What happens to the material not involved in the core collapse of a supernova?

    What happens to the material not involved in the core collapse of a supernova? This would be the outer portion of a star or any cloud that surrounds the star. All material to infinity or does some material remain close -- gravitationally close that might collapse if it could. thanks
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    I Trying to get a physical understanding of a Fermi gas

    I would like to get a more physical interpretation of conduction electrons (fermi gas) in a metal. I imagine ionized valence electrons close to the ions, with the fermi level (highest energy electrons) of the gas participating in conduction. A point of confusion for me...the first ionization...
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