UNIVERSITY OF KENT
SCHOOL OF PHYSICAL SCIENCES
Assignment 2: Galaxies
Due back: Never
What does the Faber-Jackson relationship refer to?
What is the velocity dispersion of an elliptical galaxy and how is it observed to be related to the luminosity? What is the typical velocity dispersion in km/s?
What is the mass and luminosity of dwarf ellipticals and giant elliptical?
Which type of galaxy is most likely to have the highest star formation rate: E, SO, Sa or Sd?
State (i) the size scale, (ii) the typical velocity dispersion and (iii) the typical total mass for a rich cluster of galaxies.
The Tully-Fisher relation allows us to estimate the true luminosity of a spiral galaxy by measuring its
B) period of variability in brightness,
C) rotation rate,
D) colour or
E) number of spiral arms.
Estimate the mass of the spiral galaxy NGC 5746 out to a radius of 100 arcseconds, as implied by the rotation curve below. Take the distance, D, to the galaxy as given by Hubble’s Law: D = v/(Hc) where H =72 km/s/Mpc where v is the redshifted speed.