Quarks Final Review

HR Diagram

A graph that plots stars according to their luminosity and temperature.

Main sequence

A continuous and distinctive band of stars that appears on plots of stellar brightness versus stellar temperature.

Wein’s Law

A law stating that the peak wavelength (λmax) of light emitted by a blackbody is inversely proportional to its temperature (T).

Stefan’s Law

A law stating that the total energy radiated per unit surface area of a black body is proportional to the fourth power of its temperature.

Parallax

The apparent shift of an object’s position against the background of distant stars, used to measure distance.

Variable stars

Stars that fluctuate in brightness, used for measuring distances through the period-luminosity relationship.

Core-collapse supernova

A type of supernova that occurs when the core of a massive star collapses under its own gravity.

White dwarfs

Remnants of low-mass stars that have exhausted their nuclear fuel and consist mainly of electron-degenerate matter.

Neutron stars

Dense remnants of massive stars that have undergone a supernova explosion, primarily composed of neutrons.

Black holes

Regions of space where the gravitational pull is so strong that nothing, not even light, can escape from them.

Escape velocity

The minimum speed an object must reach to break free from a gravitational field without any propulsion.

Event Horizon

The boundary around a black hole beyond which no light or other radiation can escape.

Principle of equivalence

The concept that gravitational and inertial effects are indistinguishable in a locally flat spacetime.

Gravitational time dilation

The phenomenon where time runs slower in stronger gravitational fields compared to weaker fields.

Milky Way galaxy structure

The Milky Way consists of a disk with stars and gas, a bulge with older stars, and a halo that contains globular clusters.

Hubble’s Law

The observation that the recessional velocity of galaxies is proportional to their distance from us.

Redshift

The increase in wavelength (or decrease in frequency) of light from an object moving away from the observer, indicating an expanding universe.

Spiral galaxies

Galaxies characterized by a disk structure with spiral arms, formed by density waves and supported by rotational motion.

Elliptical galaxies

Galaxy type with no disk or spiral arms, often composed of old stars and lacking gas and dust.

Irregular galaxies

Galaxies that do not have a distinct shape or structure and often contain significant amounts of gas and dust.

Critical density

The density of matter in the universe required for it to be flat, determining the long-term behavior of the universe's expansion.

Cosmological constant

A value introduced by Einstein in his equations of General Relativity, representing a constant energy density filling space homogeneously.