Astronomy Finals Study Guide Pt.2 (copy)

Core Pressure and Temperature

The core pressure and temperature of a main-sequence star are determined by its mass.

Higher Mass Stars

Stars with higher mass that have greater luminosities, shorter lifetimes, and higher core temperatures due to rapid fusion rates.

Lower Mass Stars

Stars that have smaller luminosities, longer lifetimes, cooler cores, and deeper convective zones.

Life Tracks of Stars

The insights gained from studying star clusters that contain stars of different masses born around the same time.

Red Giant

A stage in the life of a star whereby, after exhausting hydrogen fusion, the core cools and shrinks leading to expansion.

Helium Flash

The rapid increase in helium fusion rate when the core temperature of a low-mass red giant rises enough for helium to fuse.

Planetary Nebula

The stage in stellar evolution when helium fuses in a shell around the core after exhausting helium, ejecting the outer layers.

Supernova

An explosion resulting from the collapse of an iron core under gravity, at which point heavier elements are formed.

CNO cycle

A fusion process occurring in high-mass stars where carbon, nitrogen, and oxygen are used to convert hydrogen into helium.

Galaxy Structure

The Milky Way consists of a disk containing stars, gas, and dust; a dense central bulge; and a halo with older, metal-poor stars.

Stellar Orbits

Disk stars orbit in nearly circular paths within the disk, while bulge and halo stars exhibit random, elliptical orbits.

Hubble’s Discovery

Edwin Hubble's measurement of the distance to Andromeda that proved it is a separate galaxy, solving the spiral nebulae debate.

Hubble–Lemaître Law

The relationship where galaxies move away from us at a velocity proportional to their distance, indicating the expansion of the universe.

Cosmological Redshift

The stretching of light waves as the universe expands, correlating to greater distance and earlier time in the universe's history.

Big Bang Theory

A cosmological model explaining the early universe as extremely hot and dense, leading to the expansion and cooling over time.

Cosmic Microwave Background (CMB)

Leftover radiation from approximately 380,000 years after the Big Bang, revealing the universe's thermal spectrum and fluctuations.

Olbers' Paradox

The contradiction that if the universe were infinite and eternal, the night sky should be bright, explained by the universe's finite age.

Supermassive Black Holes (SMBHs)

Massive black holes located at the centers of galaxies, with their mass correlating with the mass of the galaxy bulge.

Active Galactic Nuclei (AGN)

Bright central regions of galaxies powered by supermassive black holes, producing high-energy emissions.

Star Formation Process

The process in which cold, dense clouds collapse under gravity to form stars, often occurring in molecular clouds.

Galactic Recycling

The cycle in which evolved stars return materials to the interstellar medium, allowing for the formation of new stars.