Lecture on Stellar Evolution

These flashcards cover key vocabulary and concepts associated with the evolution of stars, their characteristics, and their lifecycle based on the lecture notes.

Ant Nebula

A nebula where a star is losing mass, located about 3000 light-years from the Sun; shown in an image by the Hubble Space Telescope.

Evolution of Stars

The changes that stars undergo throughout their lifetimes, including transitions from main sequence to red giants.

H-R Diagram

A graph that plots stars' properties, such as temperature and luminosity, and shows their evolution stages.

Main Sequence Star

A stable star that derives energy primarily from nuclear fusion of hydrogen into helium.

Zero-Age Main Sequence

The point in the H-R diagram when a star begins hydrogen fusion and is no longer contracting.

Luminosity

The total amount of energy emitted by a star per unit time, which changes as the star evolves.

Helium Flash

A rapid ignition of helium fusion in the core of a red giant due to increased temperature and pressure.

Planetary Nebula

A shell of gas ejected by a dying star, illuminated by the star's ultraviolet radiation, with no relation to actual planets.

Nucleosynthesis

The process of forming new atomic nuclei from lighter ones, typically occurring in stars during fusion.

Red Giant

A late phase of a star's evolution characterized by a large size, high luminosity, and a cooler surface temperature.

Globular Cluster

A dense, spherical collection of hundreds of thousands of stars, typically very old and found in the Galaxy's halo.

Open Cluster

A loose grouping of several dozen to thousands of stars, usually younger and located in the Galaxy's plane.

Stellar Association

A collection of young stars with similar spectral types and motions, usually scattered across a region of space.

Mass Loss in Stars

The phenomenon where a star loses a significant portion of its mass during the late stages of its evolution.

Cosmic Recycling

The process by which dying stars return gas and newly formed elements to the interstellar medium, contributing to new star formation.

Fusion Rate

The speed at which nuclear reactions occur in a star's core, influenced by temperature and the elements involved.

Triple-Alpha Process

The fusion process in which three helium nuclei combine to form a carbon nucleus, occurring in the cores of stars.

Supernova

The explosive death of a massive star, often leading to the creation of heavier elements and a remnant core.

Main-Sequence Turnoff

The position in the H-R diagram where the most massive stars in a cluster evolve off the main sequence.

Helium Accumulation

The buildup of helium in a star's core due to hydrogen fusion, leading to changes in the star's structure.

Earth's Future due to Solar Evolution

The potential impacts on Earth as the Sun evolves into a red giant, including temperature increases and atmospheric changes.

Star Evolutionary Tracks

Paths on the H-R diagram that indicate how stars of different masses evolve through various stages of their life cycle.