Astronomy Chapter 23 Vocab- "The Milky Way Galaxy"

Milky Way

what our galaxy appears as in the night sky; is spiral shaped

Andromeda Galaxy

our closest spiral neighbor that resembles the Milky Way fairly closely

cataclysmic variables

the term used to describe variable stars, including novae, supernovae, and related phenomena

intrinsic variables

stars whose luminosity varies in a regular way, but much more subtly

RR Lyrae stars

stars whose luminosity curves range from 0.5 days to 1 day

Cepheids

stars whose luminosity curves range from 1-100 days

galactic halo

an area in the Milky Way where all of the stars are very old, and there is no gas and dust

galactic disk

an area in the Milky Way where the youngest stars and star formation regions are located

galactic bulge

an area in the Milky Way that surrounds the galactic center and contains a mix of older and younger stars

galactic year

the duration of time required for the Solar System to orbit once around the center of the Milky Way Galaxy; estimates that the length of one orbit ranges from 225-250 million terrestrial years

galactic center

an area of the Milky Way that appears to have stellar density a million times higher than stars near Earth, a ring of molecular gas, a strong magnetic field, a rotating ring or disk of matter, and a strong X-ray source at the center