DOCSLIB.ORG

1 Formation and Evolution of Planetary Systems

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
1 Formation and Evolution of Planetary Systems Specialist Topics in Astrophysics: Lecture 3 Formation and Evolution of Planetary Systems Ken Rice ([email protected]) Alternative Giant Planet Formation Gravitational instability model • Formed as miniature solar systems, condensing from instabilities in the initial solar nebula • Unstable ring of gas/spiral density waves developed in the Solar Nebula • A Jupiter mass collapsed under its own weight to form a giant planet Protoplanet Disk of the solar Rings form in nebula Rings collapse nebula is shrinking But they are unstable into protoplanets Disk Instabilities Numerical simulations Forming Jupiter 1 Gravitational Instabilities • Consider energies per unit mass GM GπΣR2 – Gravity E ≈ = = GπΣR g R R 1 2 – Rotation E = ()ΩR r 2 3 2 – Thermal E ≈ T ≈ c th 2 s • Rotation dominates at large R • Thermal energy dominates at small R Conditions for instability • A disc will be gravitationally unstable if gravitational energy dominates over thermal and rotational en energies – Toomre’s stability criteria E E c2 1 Ω2 R 2 c Ω th r <1⇒ s 2 < 1⇒ s <1 2π 2Σ2 2 π Σ Eg Eg G R G c Ω π – General Toomre criteria Q = s < πGΣ 2 • To achieve low Q – Increase mass - Σ – Decrease temperature – cs – Combination of the two • Disc instability believed to be possible due to – Cooling – Mass infall onto disc Fragmentation • Problems – Requires very massive and cold disc – Requires rapid cooling to maintain low temperatures. 2 Quasi -steady transport • More likely that disc will undergo a self-gravitating phase when young and massive but not fragment – Angular momentum transport Planet -Disc interactions • Planets form inside gas discs • Planets must interact with the gas disc 1 m 3 – Exert torques on gas as it flows by – Hill radius = p RH a 3M * • Induces transport of angular momentum – Planet migration • May lead to the opening of a gap in the disc – Planet can affect region of size ~ Hill radius Planet -Disc interactions • Gas inside planet • Gas outside planet – Flows quicker – Flows slower than – Loses angular planet momentum to planet – Planet loses angular – Falls inwards and momentum to gas speeds up its – Gas moves outwards rotation and slows down Forms spiral arms that transfer angular momentum from inner disc to outer disc. 3 Gap Formation • Higher-mass planets clear gaps in the disc • Gap formation requires that Hill radius > scaleheight (H) of disc – Low-mass planet – gas flows around Hill radius – High-mass planets – Hill radius > scaleheight (H) – gap • Gap size is balance between gravity and viscosity – Viscosity wants to close the gap – Gravity from planet wants to open gap – Exact size depends on resonances with planet (i.e., 2:1 resonance where gas in disc orbits twice for each planet orbit). Gaps and Planetary Migration • As planets grow they drive density waves into the remaining disk • These waves carry angular momentum and so can push gas away from the planet opening a gap Simulations by F. Masset Gap formation simulation 4 Low -mass planets • Disc material extends up to the planet – no gap • Planet excites spiral arms – Leading inside and trailing outside – Transport angular momentum through planet • Net transport removes angular from planet • Migrates inwards – Type I migration (no gap) • Migration rate proportional to the amount of material the feels the planet – Amount of gas inside Hill sphere • Lower mass planets migrate more slowly 0.1M = 5 Jup tmigrate 10 years M planet High -mass planets • Planets more massive than ~ 0.1 MJupiter open gaps • Planet depends on disc evolution for migration – Requires viscosity to replenish areas near disc resonances • Planet can only migrate on viscous timescales R 2 t = ≈ few × 10 5 years v ν • Mechanism can bring in Jupiters from 5 AU in < 1 Myr – Forms hot Jupiters – What stops them??? Separation distribution • Planets form at 5 AU • Migrate inwards on ~ 0.5 Myr timescales • If disc removed, planet stalls • In not, planet plunges into star – Possible existence of magnetospheric cavity • Probability of finding planet at radius R is ∝ ∝ 2 PR tmigrate R • Planets spend more time at large radii – More likely to find them there 5 ALMA • 50 12m radio telescope working as an interferometer – Baseline 150 m – 14 km • Resolution of 0.01 arcsec at 300 microns – 1 AU resolution at 100 pc Directly detecting protoplanets 50 pc 100 pc Inferring the presence of planets • A migrating planet could clear the inner disc of material – Gas drag may preferentially remove solid bodies • Spectral Energy Distribution can be used to infer the distribution of dust in the disc – Hot dust close to the star – Cooler dust further out • A deficit of near infrared flux suggests the presence of an inner gap – May only be a gap in the dust 6 Orbital eccentricities • Many extrasolar planets have high eccentricities – Disc migration should keep eccentricities low • Could be due to scattering – Multiple planet systems – Once gas is removed planets can interact • Chaotic orbits – Orbit crossing – Close encounters and ejections – Survivors left with high eccentricities • Instability if 1 1 ∆ ≈ 4.2 q3 + q3 long term < + ∆ 1 2 a2 a1 1( ) ∆ ≈ 3.0 short term Timescales for Planet Formation • Giant planets must have formed in about 10 million yrs – Studies of young stars show that by 10 million yrs they have blown away their gas disks – Since Jovian planets are largely gaseous, growth will have ceased when the gas was expelled from the Solar System • Terrestrial planets probably took longer to form because their growth does not require large amounts of gas • The Sun reached the main sequence (began fusing hydrogen in its core) after about 30 million yrs • The entire process of planetary formation took about ~100 million yrs (about 2% of the present age of the Solar System) What happened to all the gas? • The inner planets were not massive enough to accrete the lightest gases of the Solar Nebula • Just prior to nuclear ignition, a star will enter the “T Tauri” phase, when the stellar wind is very strong • This pressure pushed the gas out into space leaving the inner protoplanets and the already formed outer giants 7 Origin of Planetary Satellites • Remnants of an accretion disk (e.g. Galilean satellites) – Different composition with radius – Circular, low inclination orbits – Even spacing of orbits • Asteroid captures (e.g. Phobos and Deimos) – Composition similar to asteroids or comets – Eccentric and high inclination orbits • Large captures (e.g. one suggested hypothesis for the origin of the Moon) Last Stages of Planet Formation The last stages were undoubtedly dominated by violent collisions between planets and planetesimals in various phases of growth (left) resulting in a molten Earth and the formation of the Moon (right) Solar System Anomalies • Venus rotates “backwards” with respect to the Sun and its orbit around the Sun – It is postulated that a large planetesimal crashing off-centre could have disrupted Venus and altered its rotation direction • Uranus rotates on its side – Probably hit by a large planetesimal and knocked on its side • Pluto has a highly inclined orbit (18 degrees) – May have originated in a collision or near collision with a massive planetesimal – Pluto is actually not a “planet” but a “Kuiper Belt object, so the inclined orbit is not that unusual 8 Star and Planet Formation Summary Planestimal hypothesis • Minimum mass solar nebula (MMSN) − r 5.1 Σ = 42000 kg m 2- MMSN 1 AU • Disc evolves viscosly R 2 ν = αc H t = s v ν • Collisional growth 2 dm V p = ρ π 2 + esc = ρ π 2 sw Vo Rs 1 sw Vo Rs Fg dt Vo • Isolation mass (applies to both the core and final mass – envelope + core) 1 3 m 3 ()4πa2σ 2 = π σ = π 2σ isolation ⇒ = misolation 2 a 2RH 4 a misolation 1 3M () 2 * 3M * This is all consist with the fact that solar system planets all orbit in the same plane and in the same direction, and with the fact that exoplanets are found preferentially around metal-rich stars. Migration • Type I – low-mass planets – very rapid???? – May be influenced by turbulence and may be more of a random walk. 0.1M = 5 Jup tmigrate 10 years M planet • Type II – gap opening – high-mass planets – Evolves with the disc - viscously R 2 t = ≈ few × 10 5 years v ν • Type II migration explains ‘hot Jupiters’ and the radial distribution of planets 9 Eccentricity • Surprising – solar system planets have very low eccentricities. • Exoplanet eccentricities possibly due to planet-planet scattering – Interactions eject planets – Remaining planets have increased eccentricities – Free-floating planets??? • Solar system may be unusual!!! – The properties of the exoplanet systems may be due to selection effects. Conclusions • The “planetesimal hypothesis” provides a viable theory for the growth of terrestrial planets, the cores of giant planets and other smaller bodies • Growth of giant planets probably happens fast otherwise gas is lost from the nebula – Still some support for an instability mechanism for the formation of gas giants. • The formation of planetesimals is one of the weakest parts of the theory – Interaction with disc gas can produce a drag force that removes planetesimals – not clear how this is solved. • Most of the observed structure in the Solar System and exoplanets has been explained (with the exception of a few anomalies that are not too well understood…) 10.
Load more

Recommended publications
  • Setting the Stage: Planet Formation and Volatile Delivery
    Noname manuscript No. (will be inserted by the editor) Setting the Stage: Planet formation and Volatile Delivery Julia Venturini1 · Maria Paula Ronco2;3 · Octavio Miguel Guilera4;2;3 Received: date / Accepted: date Abstract The diversity in mass and composition of planetary atmospheres stems from the different building blocks present in protoplanetary discs and from the different physical and chemical processes that these experience during the planetary assembly and evolution. This review aims to summarise, in a nutshell, the key concepts and processes operating during planet formation, with a focus on the delivery of volatiles to the inner regions of the planetary system. 1 Protoplanetary discs: the birthplaces of planets Planets are formed as a byproduct of star formation. In star forming regions like the Orion Nebula or the Taurus Molecular Cloud, many discs are observed around young stars (Isella et al, 2009; Andrews et al, 2010, 2018a; Cieza et al, 2019). Discs form around new born stars as a natural consequence of the collapse of the molecular cloud, to conserve angular momentum. As in the interstellar medium, it is generally assumed that they contain typically 1% of their mass in the form of rocky or icy grains, known as dust; and 99% in the form of gas, which is basically H2 and He (see, e.g., Armitage, 2010). However, the dust-to-gas ratios are usually higher in discs (Ansdell et al, 2016). There is strong observational evidence supporting the fact that planets form within those discs (Bae et al, 2017; Dong et al, 2018; Teague et al, 2018; Pérez et al, 2019), which are accordingly called protoplanetary discs.
    [Show full text]
  • Arxiv:2012.11628V3 [Astro-Ph.EP] 26 Jan 2021
    manuscript submitted to JGR: Planets The Fundamental Connections Between the Solar System and Exoplanetary Science Stephen R. Kane1, Giada N. Arney2, Paul K. Byrne3, Paul A. Dalba1∗, Steven J. Desch4, Jonti Horner5, Noam R. Izenberg6, Kathleen E. Mandt6, Victoria S. Meadows7, Lynnae C. Quick8 1Department of Earth and Planetary Sciences, University of California, Riverside, CA 92521, USA 2Planetary Systems Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA 3Planetary Research Group, Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, NC 27695, USA 4School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA 5Centre for Astrophysics, University of Southern Queensland, Toowoomba, QLD 4350, Australia 6Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA 7Department of Astronomy, University of Washington, Seattle, WA 98195, USA 8Planetary Geology, Geophysics and Geochemistry Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA Key Points: • Exoplanetary science is rapidly expanding towards characterization of atmospheres and interiors. • Planetary science has similarly undergone rapid expansion of understanding plan- etary processes and evolution. • Effective studies of exoplanets require models and in-situ data derived from plan- etary science observations and exploration. arXiv:2012.11628v4 [astro-ph.EP] 8 Aug 2021 ∗NSF Astronomy and Astrophysics Postdoctoral Fellow Corresponding author: Stephen R. Kane, [email protected] {1{ manuscript submitted to JGR: Planets Abstract Over the past several decades, thousands of planets have been discovered outside of our Solar System. These planets exhibit enormous diversity, and their large numbers provide a statistical opportunity to place our Solar System within the broader context of planetary structure, atmospheres, architectures, formation, and evolution.
    [Show full text]
  • Dynamical Evolution of Planetary Systems
    Dynamical Evolution of Planetary Systems Alessandro Morbidelli Abstract Planetary systems can evolve dynamically even after the full growth of the planets themselves. There is actually circumstantial evidence that most plane- tary systems become unstable after the disappearance of gas from the protoplanetary disk. These instabilities can be due to the original system being too crowded and too closely packed or to external perturbations such as tides, planetesimal scattering, or torques from distant stellar companions. The Solar System was not exceptional in this sense. In its inner part, a crowded system of planetary embryos became un- stable, leading to a series of mutual impacts that built the terrestrial planets on a timescale of ∼ 100My. In its outer part, the giant planets became temporarily unsta- ble and their orbital configuration expanded under the effect of mutual encounters. A planet might have been ejected in this phase. Thus, the orbital distributions of planetary systems that we observe today, both solar and extrasolar ones, can be dif- ferent from the those emerging from the formation process and it is important to consider possible long-term evolutionary effects to connect the two. Introduction This chapter concerns the dynamical evolution of planetary systems after the re- moval of gas from the proto-planetary disk. Most massive planets are expected to form within the lifetime of the gas component of protoplanetary disks (see chapters by D’Angelo and Lissauer for the giant planets and by Schlichting for Super-Earths) and, while they form, they are expected to evolve dynamically due to gravitational interactions with the gas (see chapter by Nelson on planet migration).
    [Show full text]
  • Abstracts of Extreme Solar Systems 4 (Reykjavik, Iceland)
    Abstracts of Extreme Solar Systems 4 (Reykjavik, Iceland) American Astronomical Society August, 2019 100 — New Discoveries scope (JWST), as well as other large ground-based and space-based telescopes coming online in the next 100.01 — Review of TESS’s First Year Survey and two decades. Future Plans The status of the TESS mission as it completes its first year of survey operations in July 2019 will bere- George Ricker1 viewed. The opportunities enabled by TESS’s unique 1 Kavli Institute, MIT (Cambridge, Massachusetts, United States) lunar-resonant orbit for an extended mission lasting more than a decade will also be presented. Successfully launched in April 2018, NASA’s Tran- siting Exoplanet Survey Satellite (TESS) is well on its way to discovering thousands of exoplanets in orbit 100.02 — The Gemini Planet Imager Exoplanet Sur- around the brightest stars in the sky. During its ini- vey: Giant Planet and Brown Dwarf Demographics tial two-year survey mission, TESS will monitor more from 10-100 AU than 200,000 bright stars in the solar neighborhood at Eric Nielsen1; Robert De Rosa1; Bruce Macintosh1; a two minute cadence for drops in brightness caused Jason Wang2; Jean-Baptiste Ruffio1; Eugene Chiang3; by planetary transits. This first-ever spaceborne all- Mark Marley4; Didier Saumon5; Dmitry Savransky6; sky transit survey is identifying planets ranging in Daniel Fabrycky7; Quinn Konopacky8; Jennifer size from Earth-sized to gas giants, orbiting a wide Patience9; Vanessa Bailey10 variety of host stars, from cool M dwarfs to hot O/B 1 KIPAC, Stanford University (Stanford, California, United States) giants. 2 Jet Propulsion Laboratory, California Institute of Technology TESS stars are typically 30–100 times brighter than (Pasadena, California, United States) those surveyed by the Kepler satellite; thus, TESS 3 Astronomy, California Institute of Technology (Pasadena, Califor- planets are proving far easier to characterize with nia, United States) follow-up observations than those from prior mis- 4 Astronomy, U.C.
    [Show full text]
  • Planetary Migration: What Does It Mean for Planet Formation?
    ANRV374-EA37-14 ARI 23 March 2009 12:18 Planetary Migration: What Does It Mean for Planet Formation? John E. Chambers Carnegie Institution for Science, Washington, DC 20015; email: [email protected] Annu. Rev. Earth Planet. Sci. 2009. 37:321–44 Key Words First published online as a Review in Advance on extrasolar planet, protoplanetary disk, accretion, hot Jupiter, resonance January 22, 2009 The Annual Review of Earth and Planetary Sciences is Abstract online at earth.annualreviews.org by University of British Columbia Library on 12/29/09. For personal use only. Gravitational interactions between a planet and its protoplanetary disk This article’s doi: change the planet’s orbit, causing the planet to migrate toward or away 10.1146/annurev.earth.031208.100122 from its star. Migration rates are poorly constrained for low-mass bodies Annu. Rev. Earth Planet. Sci. 2009.37:321-344. Downloaded from arjournals.annualreviews.org Copyright c 2009 by Annual Reviews. ! but reasonably well understood for giant planets. In both cases, significant All rights reserved migration will affect the details and efficiency of planet formation. If the disk 0084-6597/09/0530-0321$20.00 is turbulent, density fluctuations will excite orbital eccentricities and cause orbits to undergo a random walk. Both processes are probably detrimental to planet formation. Planets that form early in the lifetime of a disk are likely to be lost, whereas late-forming planets will survive and may undergo little migration. Migration can explain the observed orbits and masses of extra- solar planets if giants form at different times and over a range of distances.
    [Show full text]
  • Scientific Goals for Exploration of the Outer Solar System
    Scientific Goals for Exploration of the Outer Solar System Explore Outer Planet Systems and Ocean Worlds OPAG Report v. 28 August 2019 This is a living document and new revisions will be posted with the appropriate date stamp. Outline August 2019 Letter of Response to Dr. Glaze Request for Pre Decadal Big Questions............i, ii EXECUTIVE SUMMARY ......................................................................................................... 3 1.0 INTRODUCTION ................................................................................................................ 4 1.1 The Outer Solar System in Vision and Voyages ................................................................ 5 1.2 New Emphasis since the Decadal Survey: Exploring Ocean Worlds .................................. 8 2.0 GIANT PLANETS ............................................................................................................... 9 2.1 Jupiter and Saturn ........................................................................................................... 11 2.2 Uranus and Neptune ……………………………………………………………………… 15 3.0 GIANT PLANET MAGNETOSPHERES ........................................................................... 18 4.0 GIANT PLANET RING SYSTEMS ................................................................................... 22 5.0 GIANT PLANETS’ MOONS ............................................................................................. 25 5.1 Pristine/Primitive (Less Evolved?) Satellites’ Objectives ...............................................
    [Show full text]
  • Pebble-Driven Planet Formation for TRAPPIST-1 and Other Compact Systems
    UvA-DARE (Digital Academic Repository) Pebble-driven planet formation for TRAPPIST-1 and other compact systems Schoonenberg, D.; Liu, B.; Ormel, C.W.; Dorn, C. DOI 10.1051/0004-6361/201935607 Publication date 2019 Document Version Final published version Published in Astronomy & Astrophysics Link to publication Citation for published version (APA): Schoonenberg, D., Liu, B., Ormel, C. W., & Dorn, C. (2019). Pebble-driven planet formation for TRAPPIST-1 and other compact systems. Astronomy & Astrophysics, 627, [A149]. https://doi.org/10.1051/0004-6361/201935607 General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl) Download date:28 Sep 2021 A&A 627, A149 (2019) Astronomy https://doi.org/10.1051/0004-6361/201935607 & © ESO 2019 Astrophysics Pebble-driven planet formation for TRAPPIST-1 and other compact systems Djoeke Schoonenberg1, Beibei Liu2, Chris W.
    [Show full text]
  • Characterizing Exoplanet Habitability
    Characterizing Exoplanet Habitability Ravi kumar Kopparapu NASA Goddard Space Flight Center Eric T. Wolf University of Colorado, Boulder Victoria S. Meadows University of Washington Habitability is a measure of an environment’s potential to support life, and a habitable exoplanet supports liquid water on its surface. However, a planet’s success in maintaining liquid water on its surface is the end result of a complex set of interactions between planetary, stellar, planetary system and even Galactic characteristics and processes, operating over the planet’s lifetime. In this chapter, we describe how we can now determine which exoplanets are most likely to be terrestrial, and the research needed to help define the habitable zone under different assumptions and planetary conditions. We then move beyond the habitable zone concept to explore a new framework that looks at far more characteristics and processes, and provide a comprehensive survey of their impacts on a planet’s ability to acquire and maintain habitability over time. We are now entering an exciting era of terrestiral exoplanet atmospheric characterization, where initial observations to characterize planetary composition and constrain atmospheres is already underway, with more powerful observing capabilities planned for the near and far future. Understanding the processes that affect the habitability of a planet will guide us in discovering habitable, and potentially inhabited, planets. There are countless suns and countless earths all rotat- have the capability to characterize the most promising plan- ing around their suns in exactly the same way as the seven ets for signs of habitability and life. We are at an exhilarat- planets of our system.
    [Show full text]
  • Book of Abstracts Download
    Exoplanets and Planet Formation Monday 11 December 2017 - Friday 15 December 2017 Shanghai Book of Abstracts Contents Abrupt climate transition of icy worlds from snowball to moist or runaway greenhouse 0 1 Formation of Super-Earths by Tidally-Forced Turbulence 2 . 1 Clearing Residual Planetesimals By Sweeping Secular Resonances In Transitional Disks: A Lone-Planet Scenario For The Wide Gaps In Debris Disks Around Vega And Fomalhaut 3............................................... 1 Dust-free modeling of dusty protoplanetary disks 4 . 2 Vertical shear instability in dusty protoplanetary disks 5 . 2 New Frontier of Exoplanetary Science: High Dispersion Coronagraphy 6 . 3 Searching for Exoplanet from Dome A Antarctica 7 . 3 Migration of low-mass planets in laminar discs 8 . 3 Magnetospheric rebound: a mechanism to re-arrange the orbital configurations of close-in super-Earths during disk dispersal 9 . 4 Measuring the mass of Proxima Cen from a microlensing event 10 . 4 Why is there no Hilda planet in our Solar System? 11 . 4 What JWST will bring to exoplanet origin and characterization 12 . 5 Formation of massive planetary companions and free-floating Jupiters through circumstel- lar disk fragmentation 13 . 5 Exo-Nephology: 3D simulations of cloudy hot-Jupiter atmospheres with the UK Met Office climate model. 14 . 5 Dynamical evolution of inner planet systems with outer giant planet scatterings 15 . .6 Multiplanet Systems as Laboratories for Planet Formation 16 . 6 Microphysical Modeling of Convective Dust Clouds in Warm Super-Earths 18 . 6 Vortex survival in 3D self-gravitating discs 19 . 7 Pebble Accretion in Turbulent Protoplanetary Disks 20 . 7 Discovering the Interior of Jupiter with Juno 21 .
    [Show full text]
  • Planet Migration in Planetesimal Disks
    PLANET MIGRATION IN PLANETESIMAL DISKS Harold F. Levison Southwest Research Institute, Boulder Alessandro Morbidelli Observatoire de la Coteˆ d'Azur Rodney Gomes Observatorio´ Nacional, Rio de Janeiro Dana Backman USRA & SETI Institute, Moffett Field Planets embedded in a planetesimal disk will migrate as a result of angular momentum and energy conservation as the planets scatter the planetesimals that they encounter. A surprising variety of interesting and complex dynamics can arise from this apparently simple process. In this Chapter, we review the basic characteristics of planetesimal-driven migration. We discuss how the structure of a planetary system controls migration. We describe how this type of migration can cause planetary systems to become dynamically unstable and how a massive planetesimal disk can save planets from being ejected from the planetary system during this instability. We examine how the Solar System's small body reservoirs, particularly the Kuiper belt and Jupiter's Trojan asteroids, constrain what happened here. We also review a new model for the early dynamical evolution of the outer Solar System that quantitatively reproduces much of what we see. And finally, we briefly discuss how planetesimal driven migration could have affected some of the extra-solar systems that have recently been discovered. 1. INTRODUCTION planet, tend to lie on one side of the planet in question or another, there will be a net flux of material inward or out- Our understanding of the origin and evolution of planets ward. The planet must move in the opposite direction in has drastically transformed in the last decade. Perhaps the order to conserve energy and angular momentum.
    [Show full text]
  • Mordasini Review of Planetary Population Synthesis
    Planetary Population Synthesis Christoph Mordasini Contents Confronting Theory and Observation.............................................. 2 Statistical Observational Constraints.............................................. 4 Frequencies of Planet Types................................................... 4 Distributions of Planetary Properties ............................................ 5 Correlations with Stellar Properties............................................. 6 Population Synthesis Method.................................................... 7 Workflow of the Population Synthesis Method.................................... 7 Overview of Population Synthesis Models in the Literature.......................... 8 Global Models: Simplified but Linked........................................... 10 Low-Dimensional Approximation.............................................. 11 Probability Distribution of Disk Initial Conditions................................. 22 Results...................................................................... 23 Initial Conditions and Parameters............................................... 24 Formation Tracks............................................................ 25 Diversity of Planetary System Architectures...................................... 26 The a M Distribution...................................................... 28 The a R Distribution....................................................... 31 The Planetary Mass Function and the Distributions of a, R and L .................... 33 Comparison
    [Show full text]
  • Other Planetary Systems the New Science of Distant Worlds
    BENN6189_05_C13_PR5_V3_TT.QXD 10/31/07 8:03 AM Page 394 13 Other Planetary Systems The New Science of Distant Worlds LEARNING GOALS 13.1 Detecting Extrasolar Planets 13.3 The Formation of Other Solar Systems ◗ Why is it so difficult to detect planets around other stars? ◗ Can we explain the surprising orbits of many extrasolar ◗ How do we detect planets around other stars? planets? ◗ Do we need to modify our theory of solar system 13.2 The Nature of Extrasolar Planets formation? ◗ What have we learned about extrasolar planets? ◗ How do extrasolar planets compare with planets in our 13.4 Finding More New Worlds solar system? ◗ How will we search for Earth-like planets? 394 BENN6189_05_C13_PR5_V3_TT.QXD 10/31/07 8:03 AM Page 395 How vast those Orbs must be, and how inconsiderable Before we begin, it’s worth noting that these discoveries this Earth, the Theatre upon which all our mighty have further complicated the question of precisely how we Designs, all our Navigations, and all our Wars are define a planet. Recall that the 2005 discovery of the Pluto- transacted, is when compared to them. A very fit like world Eris [Section 12.3] forced astronomers to recon- consideration, and matter of Reflection, for those sider the minimum size of a planet, and the International Kings and Princes who sacrifice the Lives of so many Astronomical Union (IAU) now defines Pluto and Eris as People, only to flatter their Ambition in being Masters dwarf planets. In much the same way that Pluto and Eris of some pitiful corner of this small Spot.
    [Show full text]