Planetary Systems Now

Contents
Preface
About the Editors
Acknowledgments
Chapter 1 The Compositional Dimension of Planet Formation
	1. Introduction
		1.1. Planet formation: Basic concepts
		1.2. Chemistry in planet formation: Basic concepts
	2. The Initial Chemical Budget of Planet Formation
		2.1. Protoplanetary disks
		2.2. The host stars and their composition
		2.3. Meteorites, comets and extrasolar materials
	3. Compositional Structure of Protoplanetary Disks
		3.1. Metallicities of refractory materials, organics and ices
		3.2. Modeling the compositional structure of gas and solids
		3.3. Effects of dust evolution and planetesimal formation
	4. Compositional Signatures of Planet Formation
		4.1. The limits of the C/O ratio
		4.2. Expanding the inventory of elemental ratios
	5. Future Outlooks and Concluding Remarks
	6. Q&A
	References
Chapter 2 The Mercurial Sun at the Heart of Our Solar System
	1. Introduction
	2. A Nonmagnetic Sun
	3. Magnetic Sun
	4. The Sun, Stars and Life on Earth
	5. A Closer Look
		5.1. Stars like the Sun
		5.2. Stars of solar mass through time
		5.3. Flares and CMEs
	6. Conclusions
	7. Q&A
	References
	Appendix: The Sun’s Magnetic Engine
Chapter 3 Twenty-Five Years of Exoplanet Discoveries: The Exoplanet Hosts
	1. The Relevance of the Properties of the Planet Hosts
	2. Characteristics of the Confirmed Stellar Hosts up to October 2021
		2.1. Radial velocity hosts
		2.2. Transit hosts
		2.3. Direct imaging hosts
		2.4. Microlensing hosts
		2.5. The sky distribution of the planet hosts
	3. Links between the Properties of the Host Stars and Their Planets
		3.1. Occurrence rates per star type
			3.1.1. Examples from RV surveys
			3.1.2. Examples from transit surveys
			3.1.3. Examples from direct imaging surveys
			3.1.4. Examples from microlensing surveys
		3.2. Correlations with metallicity
			3.2.1. Giant planet — metallicity correlation
			3.2.2. Planet distance/period — metallicity trend
		3.3. Correlations with stellar mass
		3.4. Chemical signatures of planet formation
	4. Conclusions
	5. Q&A
	References
Chapter 4 Exploration of the Atmospheres of the Terrestrial Planets
	1. Introduction: Comparative Planetology
	2. Generalities on Planetary Atmospheres
		2.1. Equilibrium temperature and greenhouse effect
		2.2. Thermal escape to space
	3. Observation Techniques
	4. Terrestrial Planets
		4.1. Mercury
		4.2. Venus
		4.3. Earth
		4.4. Mars
	5. Q&A
	References
Chapter 5 Atmospheres and Climates of Telluric Planets of the Solar System (and a Bit of Giant Planets and Exoplanets)
	1. A Diversity of Planetary Atmospheres
		1.1. Earth
		1.2. Mars
		1.3. Venus
		1.4. Titan
	2. The Vertical Structure of Planetary Atmospheres
		2.1. Basic energy balance
		2.2. Two-beam model
		2.3. Two-beam equations
		2.4. Radiative temperature profile
		2.5. Greenhouse effect
		2.6. Discontinuity surface-atmosphere
		2.7. Atmospheric vertical structure
		2.8. Word of caution
	3. Atmospheric Circulations
		3.1. Impact of temperature gradients
			3.1.1. Scale heights
			3.1.2. Thermally direct circulations
			3.1.3. Hadley cells and other thermally direct circulations
			3.1.4. Hadley cells’ impact on heat transport and clouds
			3.1.5. Hadley cells on Mars and the Earth
		3.2. Impact of planetary rotation
			3.2.1. Atmospheric dynamics in rotating planets
			3.2.2. Hadley cells in rotating planets
			3.2.3. Super-rotation and non-axisymmetric circulations
	4. Concluding Remarks
	5. Q&A
	References
Chapter 6 Habitability and Atmospheric Biosignatures in an Exoplanetary Context
	1. Introduction
	2. Habitability
		2.1. Definition
		2.2. Historical context
		2.3. Factors affecting habitability
		2.4. Evolution of habitability: Venus-Earth-Mars compared
		2.5. Evolution of habitability: Case study Earth
		2.6. Habitability classes
		2.7. Habitable zones
		2.8. Exoplanets in the habitable zone
		2.9. Examples of potentially habitable worlds
			2.9.1. Proxima Centauri-b
			2.9.2. K2-18b
			2.9.3. LHS-1140b
		2.10. Observing planetary habitability
	3. Biosignatures and Life
		3.1. Defining life
		3.2. Biosignature methods
		3.3. Atmospheric biosignatures: Photochemical effects
		3.4. Atmospheric biosignatures: Transmission spectroscopy
		3.5. False positives and negatives
		3.6. The ideal atmospheric biosignature and reporting protocols
	4. Summary
	5. Q&A
	References
Chapter 7 The Nature of Gas Giant Planets
	1. Introduction
	2. Modeling Planetary Interiors
		2.1. Mass and radius
		2.2. Polytropic models
	3. Interior Models
		3.1. The EoS of hydrogen, helium and heavies
			3.1.1. Hydrogen
			3.1.2. Hydrogen–Helium
			3.1.3. Heavy elements
			3.1.4. Empirical EoS
	4. Jupiter
	5. Saturn
	6. Composition-Agnostic Models
	7. Winds on Jupiter and Saturn
	8. Love Numbers
	9. Summary and Outlook
	10. Q&A
	References
Chapter 8 The Ice Giants Uranus and Neptune: Current Data and Future Exploration
	1. Uranus and Neptune Planetary Systems
		1.1. Formation and interior
		1.2. Satellites and rings
		1.3. Magnetospheres
	2. Atmospheres
		2.1. Thermal structure
		2.2. The visible clouds
		2.3. Winds
	3. The Deep Weather Layer
	4. The Future: New Observatories and Future Missions to the Icy Giants
		4.1. James Webb Space Telescope
		4.2. Ground-based large telescopes in the optical
		4.3. Ground-based observatories in the mm and radio
		4.4. Missions to Uranus and/or Neptune
	5. Q&A
	Acknowledgments
	References
Chapter 9 Cloud Formation in Exoplanetary Atmospheres
	1. Introduction
	2. A Basic Concept for Cloud Formation
	3. A Timescale Analysis
	4. Cloud Formation Modeling
		4.1. Modeling the formation of condensation seeds
		4.2. Modeling the bulk growth of cloud particles
	5. The Resulting Cloud Structure, the Prerequisites for Extrasolar Weather Forecast
	6. Moving Forward
	7. Final Thoughts
	8. Q&A
	Acknowledgments
	References
Chapter 10 Planetary Astrophysics of Small Bodies
	1. Introduction
	2. The Comets
		2.1. Destruction of the comets
	3. Asteroids
		3.1. Spectral and compositional gradients
		3.2. Active asteroids
			3.2.1. Impact
			3.2.2. Rotational instability
			3.2.3. Thermal destruction
			3.2.4. Sublimation
	4. Kuiper Belt
		4.1. Planetary migration and late-heavy bombardment
		4.2. Unseen planet
		4.3. Giant planet Trojans
	5. Q&A
	References
Chapter 11 Physical Properties of Solar System Minor Bodies: Remote Observations vs. Modeling
	1. Introduction
	2. Observables and Physical Properties
		2.1. Variations with time
		2.2. Variations over long-time periods
		2.3. Variations with solar phase angle
		2.4. Variations with wavelength
			2.4.1. Non-independent variables
	3. Concluding Remarks
	4. Q&A
	Acknowledgments
	References
Chapter 12 Surface Composition of the Trans-Neptunian Objects: Where are the Ices in the Solar System?
	1. Small Bodies, a Treasure Trove for the Understanding of Solar Systems
	2. Trans-Neptunian Bodies, Frozen Time Capsules
	3. Surface Composition of TNOs
		3.1. Icy dwarf planets
		3.2. Surface composition of mid-size and small TNOs
	4. The Future is Here: The James Webb Space Telescope
		4.1. How will JWST study the ingredients of TNOs?
			4.1.1. Water ice
			4.1.2. Complex organics
			4.1.3. Amorphous silicates
			4.1.4. Methanol ice
			4.1.5. Methane and light-hydrocarbons
			4.1.6. Minor components
	5. Extending the Study of the Surface Composition by Means of Spitzer/NIRCAM Observations
	6. Summary
	7. Q&A
	Acknowledgments
	References
Chapter 13 Interstellar Planetesimals
	1. An Astounding Yet Expected Discovery
	2. Interstellar Planetesimals are a Byproduct of Planet Formation and Evolution
		2.1. Debris disks provide observational evidence that planetesimal formation is common and that the planetesimal belts are depleted with time
		2.2. The unbinding of exo-Oort cloud objects enrich the interstellar medium with planetesimals
	3. Size Distribution of Interstellar Planetesimals
	4. Number Density of Interstellar Planetesimals
		4.1. Number density inferred from 1I/’Oumumua’s detection
		4.2. Expected contribution from the ejection of planetesimals from protoplanetary disks
		4.3. Expected contribution from the release of planetesimals from exo-Oort clouds
		4.4. Proposed solutions for the discrepancy between the inferred and expected number density of interstellar planetesimals
			4.4.1. 1I/’Oumuamua could have originated in a young nearby system
			4.4.2. 1I/’Oumuamua could be the result of a formation/fragmentation process with a narrow size distribution
	5. An Unexpected Trajectory Leading to Unconventional Ideas About Origin
		5.1. Cosmic dust bunnies and primordial planet building blocks
	6. 2I/Borisov: A Planetesimal Ejected from the Cold Outer Edge of a Distant Planetary System
	7. Interstellar Planetesimals are Potential Seeds for Planet Formation and Life
		7.1. Planetesimal can be transferred between young planetary systems
		7.2. Interstellar planetesimals can act as condensation nuclei for planet formation
	8. Future Prospects
	9. Q&A
	References
Chapter 14 Planetesimal/Debris Disks
	1. What are Debris Disks?
	2. Basic Properties and Observables
		2.1. Debris disk formation
	3. Collisional Evolution
		3.1. The outliers
	4. Resolved Observations
		4.1. Scattered light observations
		4.2. Thermal emission at mm wavelengths
			4.2.1. Radius distribution
			4.2.2. Widths
			4.2.3. Radial structures
			4.2.4. Vertical structures
	5. Circumstellar Gas
		5.1. Absorption lines
		5.2. Emission lines
		5.3. Evolution of exocometary gas
		5.4. Implications
	6. Acknowledgments
	7. Q&A
	References
Index