Download Red Shift Explanation and Questions

P1.17 Binary stars
Binary stars are a pair of stars that orbit around one another.
Click to see how the stars move.
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P1.17 Binary stars
Some binary stars will be rotating so that we can see the shape of
their orbits.
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P1.17 Binary stars
But for some binary stars we will be looking along the plane of their
orbit. These pairs will just appear to be moving sideways.
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P1.17 Binary stars
The light from stars like this can be analysed to find out which way
they are moving.
Whichever star is on this side is
moving away from the Earth.
Whichever star is on this side is
moving towards the Earth.
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copyright free. This document may have been altered from the original.
P1.17 Binary stars
We can think about just one of the stars:
When the star is in this part of its
orbit, it is not moving towards or
away from the Earth.
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copyright free. This document may have been altered from the original.
P1.17 Binary stars
The black lines in the spectrum of
light from the star will be in the
same position as if the star was
not moving at all.
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copyright free. This document may have been altered from the original.
P1.17 Binary stars
When the star is in this part of its
orbit, it is moving away from the
Earth.
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P1.17 Binary stars
The black lines in the spectrum of
light from the star will be shifted
towards the red end of the
spectrum.
Spectrum for a stationary star.
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P1.17 Binary stars
When the star is in this part of its
orbit, it is moving towards the
Earth.
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copyright free. This document may have been altered from the original.
P1.17 Binary stars
The black lines in the spectrum of
light from the star will be shifted
towards the blue end of the
spectrum.
Spectrum for a stationary star.
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P1.17 Binary stars
The lines in the spectrum will move continuously as the star moves
around its orbit.
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P1.17 Binary stars
The same effect will happen with light from the other star.
© Pearson Education Ltd 2011. Copying permitted for purchasing institution only. This material is not
copyright free. This document may have been altered from the original.
P1.17 Binary stars
© Pearson Education Ltd 2011. Copying permitted for purchasing institution only. This material is not
copyright free. This document may have been altered from the original.
P1.17 Binary stars
© Pearson Education Ltd 2011. Copying permitted for purchasing institution only. This material is not
copyright free. This document may have been altered from the original.