PHYS 118 Intro Astronomy - Stars II

This set of flashcards covers key vocabulary and concepts from the lecture on stellar classification, properties, and the Herzsprung-Russel Diagram.

Herzsprung-Russel Diagram

A graphical representation that plots the luminosity of stars against their spectral class, demonstrating the relationship between temperature and luminosity.

Main Sequence

A continuous and distinctive band of stars that appear on plots of stellar color versus brightness; most stars, including the sun, lie in this band.

Spectral Classification

A classification system for stars based on their spectral characteristics, determining intrinsic properties such as temperature and composition.

Luminosity Classes

Roman numeral classes that denote the luminosity of stars based on the width of their spectral lines.

Giants and Supergiants

Types of stars located above the main sequence on the H–R diagram, characterized by low temperature and high luminosity due to their large surface area.

White Dwarfs

Stars located at the lower-left corner of the H–R diagram that are hot but have low luminosity due to their small size.

Dwarf Stars

Any star of average or lower luminosity, mass, and size, including important subclasses like white dwarfs and red dwarfs.

Turnoff Mass

The mass of stars in a globular cluster that are just beginning to leave the main sequence, indicating the age of the cluster.

Hydrogen Fusion

The process by which stars convert hydrogen into helium in their cores, a phase during which they maintain hydrostatic equilibrium.

Stellar Evolution

The process by which a star changes over time, transitioning through various stages such as main sequence, giant, and supergiant.