Astronomy Section IV

The center of an active galaxy, which acts as the source of virtually all the galaxy's energy emission

• active galactic nucleus

• galactic bulge

• galactic cluster

• galactic epicenter

a galaxy that emits exceptionally large amounts of energy in the form of radiation

• irregular galaxy

• elliptical galaxy

• active galaxy

• peculiar galaxy

a galaxy that has no disk, no spiral arms, and very little visible gas and dust

• active galaxy

• elliptical galaxy

• irregular galaxy

• spiral galaxy

a thick distribution of gas and stars near the center of the galactic disk

• spiral galaxy

• galactic disk

• galactic halo

• galactic bulge

a flattened circular region that contains most of a galaxy's stars and interstellar matter

• galactic disk

• galactic bulge

• spiral arms

• galactic halo

a spherical region surrounding the galactic disk containing faint old stars

• galactic disk

• galactic bulge

• spiral arms

• galactic halo

an enormously large collection of matter, including stars, gas, dust, and black holes, which are all held together by gravitational attraction

• galaxy

• galaxy cluster

• star

• star cluster

a collection of galaxies held together by gravitational attraction

• galaxy

• galaxy cluster

• star

• star cluster

very tiny solid particles that populate the space between stars

• interstellar medium

• galactic medium

• galactic dust

• interstellar dust

the matter that exists between the stars, made up of gas and dust

• interstellar medium

• interstellar dust

• galactic medium

• galactic dust