ORIGINS 2B03 Lecture Notes - Galaxy Rotation Curve
Document Summary
Most of the universe is made up of something we don"t know (dark matter) 1933, fritz zwicky made the first estimates of the masses of clusters of galaxies w/o extra mass the galaxies would have velocities too high to stay in clusters. He measured the speeds of galaxies, then through the speeds found the mass of the whole galaxy, then compared that mass to the visible luminous mass of the galaxy which was much smaller than the whole galaxy cluster"s mass! What did zwicky find? (total mass)/(mass in stars + gas) = few hundred. There is some mass that we cannot see in these clusters. Speed of rotation can tell us the mass of the objects. Speed of rotation can be measured using spectrum lines. Your only sensitive to the mas on the inside. The circular velocity in the disk goes up and as you go further out velocity is constant.