PHYS 118 - Intro Astronomy: Galaxies II

These flashcards cover key vocabulary and concepts from the lecture on galaxies, focusing on AGNs, distance measurement techniques, and the nature of dark matter.

Active Galactic Nuclei (AGN)

Extremely energetic centers of some galaxies, often containing supermassive black holes.

Seyfert Galaxies

A type of AGN identified by broad emission lines in their optical spectra, classified as Type I or Type II.

Quasars

A highly luminous AGN that emits strong ultraviolet and blue light, as well as powerful radio waves from distant galaxies.

Tully-Fisher Law

A correlation that relates the luminosity of a galaxy to its rotation rate; faster rotation indicates more mass.

Hubble Law

The observation that galaxies are moving away from us, with their speed proportional to their distance.

Hubble Constant (H0)

The rate of expansion of the universe, calculated as 69 km/s/Mpc.

Hubble Tension

The discrepancy between measurements of the Hubble constant derived from the early universe and those from the late universe observations.

Dark Matter

A form of matter that does not emit light or energy, contributing to the gravitational forces in galaxies.

Cosmic Ladder

A series of methods for determining astronomical distances, from nearby stars to distant galaxies.

Spectroscopic Parallax

A method not involving parallax, using stellar spectra to determine luminosity and then distance.