Galaxies and Stars Vocabulary

17 vocabulary flashcards covering key terms and concepts from the lecture on galaxies and stars.

Model explaining how stars and planetary systems form from the condensation, gravitational collapse, and nuclear fusion of gas and dust within a nebula.

Solar Nebular Theory

A vast cloud of interstellar gas and dust that serves as the birthplace of stars.

Nebula

A massive system of stars, nebulae, and interstellar matter bound together by gravity; examples include the Milky Way.

Galaxy

A galaxy with a central bulge, halo, disk, and spiral arms rich in gas, dust, and both young and old stars.

Spiral Galaxy

An oval-shaped galaxy lacking spiral arms, containing mostly older stars and very little interstellar matter.

Elliptical Galaxy

A galaxy without a defined shape that often has vigorous star formation and contains both young and old stars.

Irregular Galaxy

The early stage of a star formed when condensing hydrogen in a nebula heats and begins to glow before stable fusion begins.

Protostar

The energy-producing process in stellar cores where lighter nuclei (like hydrogen) combine to form heavier nuclei (like helium).

Nuclear Fusion

A star’s intrinsic brightness (luminosity) as it would appear from a standard distance of 10 parsecs from Earth.

Absolute Magnitude

A graph plotting stars’ absolute magnitude against surface temperature, revealing patterns of stellar evolution.

Hertzsprung–Russell Diagram

The continuous band on the H–R diagram where stars spend most of their lifetimes fusing hydrogen; brightness rises with temperature and mass.

Main Sequence

A large, cool, bright star that forms after a medium-mass star exhausts its core hydrogen.

Red Giant

An extremely massive, bright, and large star capable of fusing elements up to iron; found in the upper right of the H–R diagram.

Super Giant

A small, dense, hot stellar remnant left after a red giant sheds its outer layers.

White Dwarf

An ultra-dense stellar core composed mostly of neutrons, created after certain supernova explosions.

Neutron Star

A region of space where gravity is so intense that not even light can escape, formed from the collapse of very massive stars.

Black Hole

The catastrophic explosion marking the death of a massive star, dispersing heavy elements and often leaving a neutron star or black hole.

Supernova