Physics of the Sun: A First Course
Purchasing Options
Features
- Presents step-by-step explanations for calculating the numerical models of the photosphere, convection zone, and radiative interior
- Describes the structure of polytropic spheres
- Covers the empirical properties and oscillation equations of helioseismology
- Explores the acoustic power in the Sun and the process of thermal conduction in different physical conditions
- Includes exercises and detailed simulation problems
Summary
With an emphasis on numerical modeling, Physics of the Sun: A First Course presents a quantitative examination of the physical structure of the Sun and the conditions of its extended atmosphere. It gives step-by-step instructions for calculating the numerical values of various physical quantities.
The text covers a wide range of topics on the Sun and stellar astrophysics, including the structure of the Sun, solar radiation, the solar atmosphere, and Sun-space interactions. It explores how the physical conditions in the visible surface of the Sun are determined by the opacity of the material in the atmosphere. It also presents the empirical properties of convection in the Sun and discusses how the physical parameters increase with depth through the convection zone. The author shows how certain types of "real stars" are actually polytropes and offers a simplified version of oscillation equations to highlight the properties of p- and g-modes in the Sun. He also focuses on the initial temperature rise into the chromosphere, why the temperature in the quiet corona has the value it does, and how the physics of magnetic fields help us to understand various striking phenomena that are observed on the Sun.
This text enables a practical appreciation of the physical models of solar processes. Through the included numerical modeling problems, it encourages a firm grasp of the numerical values of actual physical parameters as a function of radial location in the Sun.
Table of Contents
The Global Parameters of the Sun
Orbital Motion of the Earth
Astronomical Unit (AU)
GM and the Mass of the Sun
Power Output of the Sun: The Solar Luminosity
Radius of the Sun: R
Surface Gravity of the Sun
Escape Speed from the Solar Surface
Effective Temperature of the Sun
Shape of the Sun
Critical Frequency for Solar Oscillations
Mean Density of the Sun
Radiation Flow through the Solar Atmosphere
Radiation Field in the Solar Atmosphere
Empirical Properties of the Radiant Energy from the Sun
RTE
Optical Depth and the Concept of "the Photosphere"
Special Solutions of the RTE
Eddington–Barbier Relationship
Is Limb Brightening Possible?
Is S(tau) = a + b tau Realistic? The Gray Atmosphere
How Does Temperature Vary as a Function of tau?
Properties of the Eddington Relation
Toward a Model of the Sun: Opacity
Relationship between Optical Depth and Linear Absorption Coefficient
Two Approaches to Opacity: Atomic and Astrophysical
Atomic Physics: (i) Opacity due to Hydrogen Atoms
Atomic Physics: (ii) Opacity due to Negative Hydrogen Ions
Atomic Physics: (iii) Opacity due to Helium Atoms and Ions
Astrophysics: The Rosseland Mean Opacity
Power-Law Approximations to the Rosseland Mean Opacity
Narrow Band Opacity: Absorption Lines in the Spectrum
Toward a Model of the Sun: Ionization
Statistical Weights of Free Electrons
Saha Equation
Application of the Saha Equation to Hydrogen in the Sun
Application of the Saha Equation to Helium in the Sun
Contours of Constant Ionization: The Two Limits
Application of the Saha Equation to the Negative Hydrogen Ion
Computing a Model of the Sun: The Photosphere
Hydrostatic Equilibrium: The Scale Height
Sharp Edge of the Sun’s Disk
Preparing to Compute a Model of the Solar Photosphere
Computing a Model of the Photosphere: Step by Step
The Outcome of the Calculation
Overview of the Model of the Solar Photosphere
Convection in the Sun: Empirical Properties
Nonuniform Brightness
Granule Shapes
Upflow and Downflow Velocities
Linear Sizes of Granules
Circulation Time around a Granule
Temperature Differences between Bright and Dark Gas
Energy Flux Carried by Convection
Onset of Convection in the Sun: The Critical Gradient gad
Numerical Value of gad
Alternative Expression for gad
Computing a Model of the Sun: The Convection Zone
Quantifying the Physics of Convection: Vertical Acceleration
Velocities and Vertical Length Scales
Mixing Length Theory (MLT) of Convection
Temperature Excesses Associated with MLT Convection
MLT Convective Flux in the Photosphere
MLT Convective Flux below the Photosphere
Adiabatic and Nonadiabatic Processes
Computing a Model of the Convection Zone: Step by Step
Overview of Our Model of the Convection Zone
Radiative Transfer in the Deep Interior of the Sun
Thermal Conductivity for Photons
Flux of Radiant Energy at Radius r
Base of the Convection Zone
Temperature Gradient in Terms of Luminosity
Temperature Gradient in Terms of Pressure
Integrating the Temperature Equation
Computing a Mechanical Model of the Sun: The Radiative Interior
Computational Procedure: Step by Step
Overview of Our Model of the Sun’s Radiative Interior
Photons in the Sun: How Long before They Escape?
Global Property of the Solar Model
Does the Material in the Sun Obey the Perfect Gas Law?
Summary of Our Solar Model
Polytropes
Power-Law Behavior
Polytropic Gas Spheres
Lane–Emden Equation: Dimensional Form
Lane–Emden Equation: Dimensionless Form
Boundary Conditions for the Lane–Emden Equation
Analytic Solutions of the Lane–Emden Equation
Are Polytropes Relevant for "Real Stars"?
Calculating a Polytropic Model: Step by Step
Central Condensation of a Polytrope
Energy Generation in the Sun
pp-I Cycle of Nuclear Reactions
Reaction Rates in the Sun
Proton Collision Rates in the Sun
Conditions Required for Nuclear Reactions in the Sun
Rates of Thermonuclear Reactions: Two Contributing Factors
Temperature Dependence of Thermonuclear Reaction Rates
Rate of Reaction (c) in the pp-cycle
Neutrinos from the Sun
Generation and Propagation of Solar Neutrinos
Fluxes of Solar Neutrinos at the Earth’s Orbit
Neutrinos from Reactions other than pp-I
Detecting Solar Neutrinos on Earth
Solution of the Solar Neutrino Problem
Oscillations in the Sun: The Observations
Variability in Time Only
Variability in Space and Time
Radial Order of a Mode
Which p-Modes have the Largest Amplitudes?
Trapped and Untrapped Modes
Long-Period Oscillations in the Sun
Oscillations in the Sun: Theory
Small Oscillations: Deriving the Equations
Conversion to Dimensionless Variables
Overview of the Equations
The Simplest Exercise: Solutions for the Polytrope n = 1
What about g-Modes?
Asymptotic Behavior of the Oscillation Equations
Depth of Penetration of p-Modes beneath the Surface of the Sun
Why are Certain Modes Excited More than Others in the Sun?
Using Helioseismology to Test a Solar Model
The Chromosphere
Definition of the Chromosphere
Linear Thickness of the Chromosphere
Observing the Chromosphere on the Solar Disk
Appearance of the Chromosphere on the Disk
Properties of Supergranules in the CaK Line
Supergranules Observed in the Ha Line
The Two Principal Components of the Chromosphere
Temperature Increase into the Chromosphere: Empirical Results
Temperature Increase into the Chromosphere: Mechanical Work
Modeling the Chromosphere: The Input Energy Flux
Modeling the Chromosphere: Depositing the Energy
Modeling the Equilibrium Chromosphere: Radiating the Energy Away
Magnetic Fields in the Sun
Sunspots
Chromospheric Emission
Magnetic Fields: The Source of Solar Activity
Measurements of Solar Magnetic Fields
Empirical Properties of Solar Magnetic Fields
Interactions between Magnetic Fields and Ionized Gas
Understanding Magnetic Structures in the Sun
Amplification of Strong Solar Magnetic Fields
Why Does the Sun Have a Magnetic Cycle with P ˜ 10 Years?
Releases of Magnetic Energy
The Corona
Electron Densities
Spatial Structure in the White Light Corona
Electron Temperatures
Temperature of Line Formation
Pressure Scale Heights in the Corona
Ion Temperatures
X-Ray Line Strengths: The Emission Measure
Densities and Temperatures: Quiet Sun versus Active Regions
Gas Pressures in the Corona
Spatial Structure in the X-Ray Corona
Magnetic Structures: Loops in Active Regions
Magnetic Structures: Coronal Holes
Magnetic Structures: The Quiet Sun
Why Are Quiet Coronal Temperatures of Order 1–2MK?
Abrupt Transition from Chromosphere to Corona
Rate of Mechanical Energy Deposition in the Corona
What Heats the Corona?
Solar Flares
The Solar Wind
Global Breakdown of Hydrostatic Equilibrium in the Corona
Localized Applicability of HSE
Solar Wind Expansion: Steady State Flow
Observational Evidence for Solar Wind Acceleration
Energy Equation
Asymptotic Speed of the Solar Wind
Rate of Mass Outflow from the Sun
Coronal Mass Ejections
How Far Does the Sun’s Influence Extend in Space?
Appendix
Index
Exercises and References appear at the end of most chapters.
Author Bio(s)
Editorial Reviews
Physics of the Sun indeed starts as a ‘first course’ with a discussion of the sun’s global properties which can be easily observed and quantified. Very skillfully this information is used for a phenomenological description of the sun as observed from the earth. … very clear and easy to read. It is full of interesting bits of information … The quality of the paper, the print, and the book as a whole is very good. As far as the scope is concerned, it is clearly written for undergraduate students, but also accessible for non-students with some understanding of physics and mathematics. Style-wise, however, the book is a nice read also for experts and can thus be recommended without constraint.
—Contemporary Physics, Volume 52, Issue 3, 2011
… the scope of core physics that can be taught with the Sun as an illuminating vehicle is impressive … . For colleagues interested enough to think a bit more about this possibility or immediately keen to try, Mullan’s book is an excellent starting place. … this is a very useful book with lots of nice details supported by accessible calculations. … The idea of teaching general physics through the Sun, in both senses of the word, is surely a promising one.
—James L. Collett, Reviews, Volume 11, Issue 1, 2010
