Galaxies

An Active Galactic Nucleus is a compact, extraordinarily luminous central region of a galaxy powered by accretion onto a...

Barred spiral galaxies have a prominent linear bar structure of stars extending through the nucleus, with spiral arms or...

Blazars are AGN with relativistic jets pointed directly at Earth, producing extreme luminosity, rapid variability, and s...

The cosmic web is the large-scale structure of the Universe, consisting of filaments of galaxies surrounding vast empty ...

Dwarf galaxies are small galaxies with 10^7 to few billion stars, the most common galaxy type in the Universe.

Elliptical galaxies are smooth, featureless systems ranging from nearly spherical to highly elongated, containing predom...

A galaxy is a gravitationally bound system of stars, gas, dust, and dark matter, ranging from dwarfs with millions of st...

Galaxy clusters are the largest gravitationally bound structures in the Universe, containing hundreds to thousands of ga...

Irregular galaxies lack organized structure—no spiral arms or elliptical symmetry—appearing chaotic and asymmetric.

Quasars (quasi-stellar radio sources, though most aren't radio-loud) are the most luminous persistent objects in the Uni...

Seyfert galaxies are spiral galaxies with bright, compact nuclei showing strong emission lines, a nearby moderate-lumino...

Spiral galaxies are disk-shaped galaxies with prominent spiral arm patterns, active star formation, and significant gas ...

Starburst galaxies undergo exceptionally intense star formation at rates 100-1,000× higher than normal galaxies, consumi...

Superclusters are massive structures containing multiple galaxy clusters and groups, spanning hundreds of millions of li...