At every layer within a stable star, there is a balance between the inward pull of gravitation and the gas pressure. This is a stable equilibrium, for if gravity were greater than the gas pressure, the star would contract. On the other hand, if the gas pressure were greater, then the star would expand. In a stable configuration, the two must balance. Gas pressure in any layer thus is just equal to the weight (gravitational force) on all the matter above that given layer, in the same manner that the pressure at any depth in a pool of water equals the weight of the water above that depth, hence the term hydrostatic equilibrium. An immediate consequence is that gas pressure must increase inward toward the center of a star.
Astronomy
- A Brief History of Astronomy
- The Science of Astronomy
- Observing the Sky
- The Solar System
- Earth and its Moon
- Other Planets of the Solar System
- The Sun a Representative Star
- Observational Properties of Stars
- The Hertzsprung-Russell Diagram
- The Structure of Stars
- Formation and Evolution of Stars
- Final End States of Stars
- The Milky Way Galaxy
- Galaxies
- The Universe
- Life in the Universe
- Archaeoastronomy
- Greek Astronomy
- Foundations of Modern Astronomy
- Astronomy Defined
- Measurement Methods
- Basic Physics
- Electromagnetic Radiation (Light)
- The Scientific Method
- Naked-Eye Astronomy
- Telescopes and Observatories
- Introduction to the Solar System
- Origin and Evolution of the Solar System
- Terrestrial Planets, Gas‐Giant Planets
- Comparative Planetology: Terrestrials
- Comparative Planetology: Gas Giants
- Minor Objects: Asteroids, Comets, and More
- Other Planetary Systems
- Earth's Atmosphere
- Earth's Chemical Composition
- Interior Structure: Core, Mantle, Crust
- The Age of Earth
- Origin of the Earth‐Moon System
- Properties of Earth and the Moon
- Tidal Forces
- Evolution of the Earth‐Moon System
- Mars
- Jupiter
- Saturn
- Uranus
- Neptune
- Mercury
- Pluto
- Venus
- The Chromosphere
- The Corona
- The Sunspot Cycle
- Internal Structure; Standard Solar Model
- Energy Generation: Proton‐Proton Cycle
- Properties of the Sun
- Solar Neutrino Problem
- The Photosphere
- Helioseismology
- Stellar Parallax and Distances
- Apparent Magnitudes
- Absolute Magnitudes
- Luminosities
- Masses
- Radii
- Three Types of Astronomical Study
- Colors
- Spectral Types
- Surface Temperature
- Chemical Composition
- Luminosity Classes
- Proper Motions and Radial Velocities
- Properties of Secondary Importance
- Spectroscopic Parallax
- Hertzsprung Russell Diagram The Basics
- Main Sequence Stars
- Mass Luminosity Relationship
- Red Giants and Supergiants
- White Dwarf Stars
- Energy Generation The CNO Cycle
- Opacity
- Energy Transport
- High‐Mass Stars versus Low‐Mass Stars
- Other Types of Stars
- Equation of State
- Hydrostatic Equilibrium
- Thermal Equilibrium
- Evolution of Stars
- Formation of Stars
- Novae
- Type I Supernovae
- Type II Supernovae
- Neutron Stars (Pulsars)
- Black Holes and Binary X Ray Sources
- White Dwarf Stars
- Origin and Evolution of the Galaxy
- Interstellar Matter
- Interstellar Nebulae
- Star Clusters
- Structure of the Galaxy
- Clusters of Galaxies
- The Origin and Evolution of Galaxies
- Galaxies Types and Classifications
- Peculiar Galaxies
- Beyond the Big Bang Theory
- Observational Cosmology
- The Big Bang Theory
- Philosophical Considerations
- SETI—The Search for Extraterrestrial Intelligence
- Historical Background
- Scientific Considerations
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