An Introduction to Comets: Post-Rosetta Perspectives

Preface (Motivation and Scope)
Acknowledgements
Formal Acknowledgements
Acronyms
Symbols Used
Contents
Chapter 1: Light Curves, Orbits, and Reservoirs
	1.1 Light Curves
	1.2 Orbits and Origins
	1.3 Non-gravitational Forces
Chapter 2: The Nucleus
	2.1 Sizes and Shapes of Unresolved Nuclei
	2.2 Sizes and Shapes of Resolved Objects
	2.3 Mass and Density
	2.4 Rotational Properties
	2.5 Centripetal Accelerations
	2.6 Surface Reflectance
	2.7 Visible Colour
	2.8 Interior Structure
		2.8.1 Large-Scale Structure
		2.8.2 The Surface Layer and the Strength of Cometary Material
	2.9 Surface Processes
		2.9.1 Introduction
		2.9.2 Sublimation of Ices
		2.9.3 Energy Balance
			2.9.3.1 Simple Surface Energy Balance with Sublimation and Conduction
			2.9.3.2 Volume Absorption, Solid-State Greenhouse Effect, and Porosity
			2.9.3.3 Multi-volatile Models and Ice Fractionation
			2.9.3.4 The Amorphous-Crystalline Transition of Water Ice
			2.9.3.5 Thermal Emission from Resolved Surfaces
			2.9.3.6 Surface Roughness, Infrared Beaming, Self-Shadowing and Self-Heating
	2.10 Surface Appearance and Cometary ``Geology´´
		2.10.1 Regional Classification
		2.10.2 Textural Differences
		2.10.3 Impact Cratering
		2.10.4 Depressions, Pits, and Other Quasi-Circular Structures
		2.10.5 Fracturing
			2.10.5.1 Torque-Induced and Other Possible Tectonic Fractures
			2.10.5.2 Thermal Fractures
			2.10.5.3 Polygonal Networks
		2.10.6 Heat Trapping
		2.10.7 Activity Induced Mass Wasting
		2.10.8 Sedimentary Processes
		2.10.9 Activity in Dust-Covered Areas
		2.10.10 Dust Ponding
			2.10.10.1 The Surface Fluidization Mechanism
		2.10.11 Surface Changes in Smooth Terrains
		2.10.12 Other Circular Structures
		2.10.13 Surface Dust Transport
		2.10.14 Dune Pits
		2.10.15 Ice Exposures
		2.10.16 Other Surface Changes
		2.10.17 Evidence for Large-Scale Mass Loss
Chapter 3: Gas Emissions Near the Nucleus
	3.1 Fundamentals
	3.2 Major Species and Their Emissions
	3.3 Minor Species
	3.4 Gas Expansion
		3.4.1 The Initial Conditions
		3.4.2 The Knudsen Number
		3.4.3 Fluid Expansion
			3.4.3.1 Fluid Equations for Equilibrium Flow
			3.4.3.2 The Initial Evolution of the Velocity Distribution Function
			3.4.3.3 Analytical Solutions for the Fluid Equations
		3.4.4 The Knudsen Layer and Low Density Flow
			3.4.4.1 The Boltzmann Equation and the Direct Simulation Monte Carlo Method
			3.4.4.2 The Knudsen Penetration Number
			3.4.4.3 The Influence of Composition
		3.4.5 Examples of Near-Nucleus Gas Flow
			3.4.5.1 Cases with Spherical Sources
			3.4.5.2 Cases with Realistic Shapes
			3.4.5.3 Deviations from Insolation-Driven Activity
			3.4.5.4 Degeneracy in Surface Activity Distributions
		3.4.6 Re-Condensation and Surface Reflection of Gas Molecules
		3.4.7 The Initial Gas Temperature
		3.4.8 Effects of Porosity on Small Scales
		3.4.9 Nightside Outgassing
	3.5 Reaction Chemistry and the Extended Coma
		3.5.1 Daughter Products and the Haser Model
		3.5.2 Detailed Reaction Kinetics
		3.5.3 The Swings and Greenstein Effects
		3.5.4 Prompt Emission
		3.5.5 Other Notable UV Line Emissions
		3.5.6 Spatial and Temporal Variations of Parent and Daughter Species
	3.6 Compositional Variation with Heliocentric Distance
	3.7 Radiation Pressure on Gas Molecules and Radicals: The Neutral Tail(s)
	3.8 Isotopic Ratios
	3.9 Ortho to Para Ratios
Chapter 4: Dust Emission from the Surface
	4.1 The Point Source Approximation
	4.2 Scattering of Light by Dust
		4.2.1 Introduction and Rayleigh Scattering
		4.2.2 Scattering by Particles Close to the Wavelength
			4.2.2.1 Preliminaries
		4.2.3 Mie Theory
		4.2.4 The T-Matrix Method
		4.2.5 Computer Simulated Particles
		4.2.6 Observed Particle Structures
		4.2.7 The Discrete Dipole Approximation
		4.2.8 The Observed Phase Function at 67P
		4.2.9 The Observed Radiance
			4.2.9.1 The Optical Thin Case
			4.2.9.2 Optical Thickness Effects
		4.2.10 Inhomogeneous Particles and Maxwell Garnett Theory
	4.3 Afρ (``Afrho´´)
	4.4 Radiation Pressure
		4.4.1 Radiation Pressure Efficiency
		4.4.2 The Fountain Model
		4.4.3 The Dynamics of Fluffy Particles
	4.5 Dust Size Distributions
	4.6 The Lifting Dust Ejection Process
		4.6.1 Drag Force at the Nucleus Surface
		4.6.2 Cohesive Forces
		4.6.3 Advanced Dust Ejection Concepts
	4.7 The Influence of Drag on the Equations of Motion for the Dust
		4.7.1 Analytical Solutions
		4.7.2 Numerical Solutions
		4.7.3 Gas-Dust Energy Exchange within the Coma
	4.8 Converting Afρ to a Dust Loss Rate
	4.9 Observation of Non-uniform Dust Emission
		4.9.1 Large-Scale Structures
		4.9.2 Small-Scale Structures
		4.9.3 Transient Jet/Filament Structures
	4.10 Processes in the Innermost Coma
		4.10.1 Comparisons of Models of 67P with Data
		4.10.2 Deviations from Force-Free Radial Outflow
		4.10.3 Dust Above the Nightside Hemisphere
	4.11 Slow (Large) Moving Particles in the Coma
		4.11.1 Observations and Significance of Slow-Moving Particles
		4.11.2 Individual Particle Dynamics
		4.11.3 Neck-Lines and Dust Trails
	4.12 Radiometric Properties of Dust
		4.12.1 The Colour of Dust
		4.12.2 The Thermal Properties of Dust and Sublimation
		4.12.3 The Polarization of the Scattered Light
	4.13 Equation of Motion of Charged Dust
	4.14 The Non-volatile Composition of Dust and the Nucleus
	4.15 Refractory to Volatile Ratios
Chapter 5: The Plasma Environment
	5.1 Initial Considerations and the Solar Wind
	5.2 The Production of Cometary Ions
		5.2.1 Photoionization
		5.2.2 Charge-Exchange
		5.2.3 Electron Impact Ionization
	5.3 Dynamics of the Interaction
	5.4 Processes within the Diamagnetic Cavity
	5.5 Spectroscopy and Imaging of Plasma Tails
		5.5.1 Main Ion Species
		5.5.2 Ion Velocities
		5.5.3 Disconnection Events
Chapter 6: Comet-Like Activity in Related Objects
	6.1 Active Asteroids
	6.2 Activity of Centaurs
	6.3 Interstellar Visitors
	6.4 Comets in Close Proximity to the Sun
Chapter 7: The Loss of Comets
Chapter 8: Future Investigations of Comets
Chapter 9: Final Remarks
References
Index