Cosmology and Astrophysics Lectures

Flashcards covering key terms and concepts related to cosmology and astrophysics from the lecture notes.

Cosmology

The study of the universe from its earliest times to the present.

Observable Universe

The part of the universe that light can reach us from, limited by the age of the universe.

Units of Measurement

Measurements like mass (M), length (L), and time (T) that are fundamental in physics and can be expressed in various units.

Gravitational Force

The attractive force between two bodies due to their mass, among the four fundamental forces.

Kepler's Laws

Three laws describing the motion of planets around the sun, including elliptical orbit and area sweep in equal times.

Newton's Second Law

Describes how the acceleration of an object is produced by a net force acting on it, proportional to its mass.

Electromagnetism

A fundamental force involving electric and magnetic phenomena, characterized by the speed of light.

Nuclear Fusion

The process where light atomic nuclei combine to form heavier nuclei, releasing energy.

Half-Life

The time required for half of the radioactive nuclei in a sample to decay.

Blackbody Radiation

Theoretical radiation emitted by an idealized object that absorbs all incoming light, with a spectrum that depends on temperature.

Doppler Effect

The change in frequency or wavelength of light or sound from an object due to its motion towards or away from an observer.

Luminosity

The total amount of electromagnetic radiation emitted by a star per unit time.

Brown Dwarfs

A class of substellar objects that are too massive to be planets but not massive enough to sustain hydrogen fusion.

Quantum Mechanics

A fundamental theory in physics describing physical properties at the scale of atoms and subatomic particles.

Fermions

Particles that obey the Pauli exclusion principle, such as electrons, allowing only one fermion to occupy a quantum state.

Supernova

A stellar explosion that occurs at the end of a massive star's lifecycle, significantly increasing its brightness.

Hertzsprung-Russell Diagram

A plot of stellar luminosity against surface temperature that illustrates the different types of stars and their evolutionary stages.

Einstein's Principle of Equivalence

States that gravitational acceleration and inertial acceleration are indistinguishable in a local frame.

Planck's Constant

A fundamental constant used to describe the size of quanta in quantum mechanics; relates energy and frequency of photons.

CNO Cycle

A set of fusion reactions in stars that use carbon, nitrogen, and oxygen as catalysts to convert hydrogen into helium.

Neutron Star

A stellar remnant with a core composed primarily of neutrons, typically resulting from the collapse of a massive star.

Black Hole

A region in space with a gravitational pull so strong that nothing, not even light, can escape from it.

Proton–Proton (PP) Chain

The main nuclear fusion process that powers low-mass stars like the Sun.

Type Ia Supernova

An explosion of a white dwarf in a binary system, used as a standard candle in cosmology

Redshift (z)

A measure of how much the wavelength of light has been stretched due to motion or cosmic expansion.Redshift

Redshift

An increase in wavelength (light shifts toward red) caused by a source moving away.

Blueshift

A decrease in wavelength (light shifts toward blue) caused by a source moving toward the observer.