The luminosity of a galaxy is primarily determined by the total light output of its stars. More massive galaxies tend to have more stars, resulting in higher luminosity.

Elliptical galaxies are typically more luminous than spiral galaxies due to their higher concentration of stars and denser stellar cores.

Galaxy luminosity is often expressed in solar luminosities (L☉), which is the luminosity of our Sun. This allows for easy comparison of the brightness of different galaxies.

Arp 220 is a hyperluminous infrared galaxy known for its extremely high luminosity, powered by intense star formation and an active galactic nucleus.

Absolute luminosity refers to the intrinsic luminosity of a galaxy, corrected for the effects of dust and gas absorption. It provides a more accurate measure of the galaxy's true brightness.

The luminosity of a galaxy can vary over time due to factors such as star formation, supernovae, and interactions with other galaxies.

Dwarf galaxies are typically low-luminosity galaxies with a small number of stars and a relatively low mass.

In general, more massive galaxies tend to be more luminous due to their larger number of stars and higher star formation rates.

The Draco Dwarf Galaxy is an ultra-faint dwarf galaxy known for its exceptionally low luminosity, making it difficult to detect and study.

More luminous galaxies are generally easier to observe from Earth due to their higher brightness and greater contrast against the background sky.

Surface brightness refers to the luminosity of a galaxy per unit area, providing insights into the distribution and concentration of stars within the galaxy.

Elliptical galaxies are often characterized by high luminosity and a compact, spheroidal shape, with a relatively uniform distribution of stars.

While luminosity is not the primary factor in Hubble classification, it can be a secondary factor in distinguishing between certain types of galaxies, such as elliptical and lenticular galaxies.

Apparent luminosity refers to the luminosity of a galaxy as observed from a particular distance, taking into account the effects of distance and interstellar absorption.

Irregular galaxies are often characterized by low luminosity and an irregular, chaotic shape, with no明显的对称性.