26: Galaxies

Question 1

a galaxy whose shape is an ellipse and that contains no conspicuous interstellar material

Answer 1

elliptical galaxy

Question 2

a constant of proportionality in the law relating the velocities of remote galaxies to their distances

Answer 2

Hubble constant

Question 3

a rule that the radial velocities of remote galaxies are proportional to their distances from us

Answer 3

Hubble’s law

Question 4

a galaxy without any clear symmetry or pattern - neither a spiral nor an elliptical galaxy

Answer 4

irregular galaxy

Question 5

the ratio of the total mass of a galaxy to its total luminosity, usually expressed in units of solar mass and solar luminosity - gives a rough indication of the types of stars contained within a galaxy and whether or not substantial quantities of dark matter are present

Answer 5

mass-to-light ratio

Question 6

when lines in the spectra are displaced toward longer wavelengths (toward the red end of the visible spectrum)

Answer 6

redshift

Question 7

a flattened, rotating galaxy with pinwheel-like arms of interstellar material and young stars, winding out from its central bulge

Answer 7

spiral galaxy

Question 8

a supernova formed by the explosion of a white dwarf in a binary system and reach a luminosity of about 4.5 × 109 LSun - can be used to determine distances to galaxies on a large scale

Answer 8

type Ia supernova