Nuclear Fusion and Stellar Properties

These flashcards cover key terminology and concepts related to nuclear fusion and stellar properties as discussed in the provided lecture notes.

Nuclear Fusion

The process of combining two or more small atomic nuclei into a larger one, releasing energy.

Nuclear Fission

The process of splitting a large atomic nucleus into smaller nuclei, used in nuclear reactors.

Gravitational Equilibrium

The balance between the inward pull of gravity and the outward push of pressure in a star.

Electromagnetic Repulsion

A force that repels particles with the same charge, making it difficult for positively charged nuclei to fuse.

Strong Force

A fundamental force that binds protons and neutrons together in an atomic nucleus, overcoming electromagnetic repulsion.

Boltzmann’s Constant

A physical constant that relates the average kinetic energy of particles in a gas with the temperature of the gas.

Ideal Gas Law

A physical law that describes the behavior of ideal gases, relating pressure, volume, and temperature.

Heliosismology

The study of the solar interior through the observation of vibrations on the Sun’s surface.

Neutrinos

Subatomic particles produced in nuclear reactions, particularly in the core of stars, which interact weakly with matter.

Hertzsprung-Russell Diagram

A scatter plot of stars showing the relationship between their absolute magnitudes (luminosity) against their stellar classifications (temperature).

Main Sequence

The phase of stellar evolution where a star fuses hydrogen into helium, marked by stability in luminosity and temperature.

Red Giant

A late phase of stellar evolution when a star exhausts hydrogen in its core and expands while fusion occurs in a shell around the core.

Planetary Nebula

An astronomical object consisting of an expanding shell of gas ejected from red giants, forming a partially ionized shell.

White Dwarf

The residual core of a star after it has shed its outer layers, no longer undergoing fusion and cooling over time.

Supernova

A colossal explosion that occurs at the end of a high-mass star's life cycle, resulting in the core collapsing under gravity.

CNO Cycle

A process of stellar nucleosynthesis in high-mass stars where hydrogen is fused into helium with the help of carbon, nitrogen, and oxygen isotopes.

Degeneracy Pressure

A quantum mechanical effect that occurs in stellar remnants, providing pressure that supports objects like white dwarfs against gravitational collapse.

Fusion Rate

The rate at which nuclear fusion occurs in a star, influenced by conditions such as temperature and pressure.

Luminosity

The total amount of energy emitted by a star per second, an important factor in understanding stellar evolution.

Inverse Square Law

A principle stating that the intensity of light or other radiative energies decreases with the square of the distance from the source.

Mass Loss in Stars

The process whereby stars lose mass through stellar winds or during their death throes, significantly altering their evolution.

Protostar

An early stage of star formation, formed from a collapsing gas cloud that has not yet reached the temperatures necessary for nuclear fusion.