Astronomy Vocab Crossword

a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
a compact region at the center of a galaxy that has a much higher than normal luminosity over at least some portion of the electromagnetic spectrum with characteristics indicating that the luminosity is not produced by stars.
an extended bulge of stars that is nearly spherical in shape.
a plot of the orbital speeds of visible stars or gas in that galaxy versus their radial distance from that galaxy's centre.
a hypothetical form of matter that is thought to account for approximately 85% of the matter in the universe.
The unobserved matter required for the observed rotation of most galaxies to be consistent with their masses as inferred from luminous matter.
a morphological classification scheme for galaxies invented by Edwin Hubble in 1926.
a galaxy in which the stars and gas clouds are concentrated mainly in one or more spiral arms.
a slowly rotating spiral structure (just as the traffic density wave that moves slowly down the road).
a spiral galaxy with a central bar-shaped structure composed of stars.
a type of galaxy having an approximately ellipsoidal shape and a smooth, nearly featureless brightness profile.
a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy.
type of galaxy which is intermediate between an elliptical galaxy and a spiral galaxy in galaxy morphological classification schemes.
a spherical collection of stars that orbits a galaxy in the galactic plane.
a cluster of galaxies which themselves occur as clusters.
a cluster of galaxies which themselves occur as clusters.
A type of galaxy cluster that has an overall amorphous appearance, usually showing little overall symmetry or central concentration.
it emits no light of its own.
a distribution of matter between a distant light source and an observer.
the observation in physical cosmology that: Objects observed in deep space—extragalactic space, 10 megaparsecs (Mpc) or more—are found to have a redshift.
an empirical relationship between the mass or intrinsic luminosity of a spiral galaxy and its asymptotic rotation velocity or emission line width.
extremely luminous and were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light.
galaxies that have a small core of emission embedded at the center of an otherwise typical galaxy.