Astrology: Cosmology Flashcards
The lines missing on an absorption spectra correspond to
The emission spectra for the same atom
What happens to the wavelength of sound when its source moves away from the observer given the speed of sound won’t have changed
Hear a lower frequency/pitch
Increased wavelength
Pitch correlates to
Frequency
Which colour of light has the longest wavelength
Wavelength
What will be the shift if something is moving towards us
Wavelength is decreasing
Frequency is increasing
So blue shift
Light on an absorption spectrum will move towards the blue end
What is an absorption line spectrum
When a cold gas (outer layers of stars) forms a continuous spectrum with wavelengths of light missing
Outer layers (still ridiculously hot) absorb some of the photons of light from inside the star then emit them in random ways so there is a very low chance of being reemitted in the same direction hence appears as though they have been absorbed
Differs based on the atoms
The vast majority of galaxies are further away and their light appears to be red shifted
What does this tell us about our universe
Red shift means the wavelength is increasing and frequency is decreasing
So tells us they are moving away
Evidence that the universe is expanding
Explain the doppler shift equation
v is the speed of recession
z is the red shift factor
Negative z
red shift factor negative means blue shift
Positive z
red shift factor positive means red shift
Give an application of the doppler effect in cosmology
The study of eclipsing binary stars
Binary stars
Two stars rotating around a common centre of mass
Why is the graph for wavelength against time sinusoidal when assuming circular orbits
Less of a linear track and more circular motion
As it moves away its wavelength increases
As it moves towards its wavelength decreases
Radius of orbit
v=2pir/T
In terms of the speed of recession graph, a galaxy that is further away…
Is moving away faster
And has a greater red shift
