The Geiger - Marsden Experiment

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The Geiger - Marsden Experiment aka Rutherfords
Gold Foil Experiment
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The Geiger - Marsden Experiment aka Rutherfords
Gold Foil Experiment
We get a planetary view of the atom Nucleus
1/10,000 atoms diameter 99.9 of atoms mass is
in the nucleus BUT.....!!!
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1913 Niels Bohr
An orbiting electron must be accelerating..WHY???
Changing direction So, it must radiate
energy.WHY? Accelerating charges cause EM
radiation KE Momentum should be lost due to
E-M radiation. Electron should spiral inward to
nucleus
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Stellar Spectra Provide Info about Stars
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Stellar Spectra Provide Info about Stars
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Stellar Spectra Provide Info about Stars
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Stellar Spectra Provide Info about Stars
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Stellar Spectra Provide Info about Stars
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Larger Jump More Energy Bluer Wavelength
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Photons of all other energies (wavelengths) are
ignored and pass on by unabsorbed.
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Stellar Spectra Provide Info about Stars

• Nebula NGC 2363
• This nebula is a glowing gas cloud about
  10,000,000 LY from Earth.
• The hot stars in the Nebula emit high energy
  photons that are absorbed by the gas.
• The heated gases produce an emission spectrum and
  the particular wavelength of the red light of the
  nebula is 656nm. The exact wavelength of
  Hydrogen.

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The Suns Absorption Spectrum
The Suns Absorption Spectrum from 420 430 nm.
(TOP) The emission spectrum of Iron (Bottom)
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Stellar Spectral Classification

• In the late 1800s astronomers were trying to
  organize and make sense of all the data they were
  collecting.
• At the time, spectra studies were the most
  reliable, but there is a huge diversity of
  stellar spectra.
• In 1870s stars were classified into various
  letters based upon their spectral patterns.

"Oh, Be A Fine Girl, Kiss Me!"
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Stellar Spectral Classification
Hydrogen Balmer Lines Very Weak due to extreme
temps
Hydrogen Balmer Lines Strongest
Hydrogen Balmer Lines fading out and trace
amounts of heavier elements starting to appear
Stars containing heavier metals such as Calcium
and Iron (Including the Sun, a G2 star)
Stars containing Titanium Oxide
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Stellar Spectral Classification

• In short, the OBAFGKM system allows us to
• Identify the surface temperature of the stars
• Chemical composition of the stars

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Key Properties of Nearby Stars
So we can determine the distances and
characteristics of Stars We need a better
classification scheme
Where 4pR2 area of a sphere