Galaxies

Our Galaxy (CP Fig 19.1a)

Our Galaxy (CP Fig 19.1b)

Orbits of stars (CP Fig 19.18)

Spectral lines viewed through diffraction grating

Redshift

Blueshift

Observing Galactic Rotation

The result: A rotation curve

NB, there is an overall net redshift due the the cosmic expansion.

Rotation Curves

1996

Mass inferred from lensing: Must have dark matter

Theoretical studies of Galaxies

Images and movies from the Virgo consortium

Another Virgo Link

Galaxy collision movies