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26.7: Key Terms

Last updated

Jul 28, 2023
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- 26.6: The Expanding Universe
- 26.8: Summary

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

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

Hubble’s law: a rule that the radial velocities of remote galaxies are proportional to their distances from us

irregular galaxy: a galaxy without any clear symmetry or pattern; neither a spiral nor an elliptical galaxy

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

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

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

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

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