Chapter 16 Review: Galaxies and Cosmology
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A set of flashcards covering key vocabulary and concepts related to galaxies and cosmology.
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14 Terms
Elliptical galaxy
A type of galaxy with little gas and dust, unable to form new stars, and generally older.
Spiral galaxy
A type of galaxy with more gas and dust that actively forms new stars; most are barred spiral galaxies.
Irregular galaxy
A galaxy with no definite shape, containing gas and dust with young stars.
Standard candle
An astronomical object with a known true luminosity, allowing distance calculations by comparing observed brightness.
Cepheid variable stars
Stars whose pulsation period is related to their true luminosity, useful for measuring distances in nearby galaxies.
Type Ia Supernovae
A type of supernova that is much brighter than a Cepheid variable star, enabling distance measurements across hundreds of millions to billions of light-years.
Megaparsec (Mpc)
A unit measuring large distances in astronomy, equivalent to about 3.26 million light-years, simplifying the expression of cosmic distances.
Hubble-Lemaître law
Describes how a galaxy's recessional velocity increases with distance, indicating that the universe is expanding.
Galaxy's rotation curve
A graph showing how fast stars and gas orbit a galaxy, used to determine its mass based on gravitational equations.
Dark matter
Unseen mass that accounts for phenomena like flat rotation curves and gravitational lensing in galaxies and galaxy clusters.
Tidal tails
Streams of stars and gas pulled from galaxies during interactions or collisions, formed by uneven gravitational forces.
Active galaxy
A galaxy powered by gas falling into a central supermassive black hole, releasing large amounts of energy; most galaxies are inactive due to a lack of gas.
Quasar
An extremely bright object in the center of very distant galaxies, exhibiting high redshifts and varying brightness, indicative of an active galactic nucleus.
Starbursts
Intense star formation events triggered by galaxy collisions, also related to the growth of supermassive black holes.