PLANET FORMATION BY GRAVITATIONAL INSTABILITY? Kaitlin Kratter University of Arizona. Sagan Summer Workshop, July 2015
|
|
- Shavonne Davidson
- 5 years ago
- Views:
Transcription
1 PLANET FORMATION BY GRAVITATIONAL INSTABILITY? Kaitlin Kratter University of Arizona Sagan Summer Workshop, July 2015
2 PLANET FORMATION BY in GAS! GRAVITATIONAL INSTABILITY? Kaitlin Kratter University of Arizona Sagan Summer Workshop, July 2015
3 THE BOTTOM LINE Few disks appear to be massive enough to fragment (except perhaps at very early times) Those that do are more likely to produce more massive objects like brown dwarfs or m-stars Inward migration followed by tidal disruption most often leads to complete disruption, rather than mass reduction. But might assist in solid core formation
4 THE BOTTOM LINE Few disks appear to be massive enough to fragment (except perhaps at very early times) accretion disk studies were born in galactic / x-ray binary contexts, some of the standard assumptions Those that do are more likely to produce more made in these contexts are not well massive objects like brown dwarfs or m-stars suited to protostellar / protoplanetary disks. Inward migration followed by tidal disruption most 1. Thermodynamics are dominated often leads to complete disruption, rather than mass by stellar irradiation reduction. But might assist in solid core formation 2. H/R is not <<1
5 GLOSSARY Self-Gravity: the gravitational attraction of gas to itself is competitive with the central body Gravitational Instability: (GI) a linear, hydrodynamic instability that can arise in self-gravitating disks of gas, particles or both Fragment: a marginally bound gas clump that forms as the nonlinear outcome of GI Planet: depends on whom you ask
6 WHAT IS GRAVITATIONAL INSTABILITY? A hydrodynamic instability that arises in rotational;y supported disks when selfgravity wins out over pressure support on small scales, and stabilization due to shear on large scales Q = c s G = f M H M D r P Fg Ω Toomre s Q, rewritten this way can point us toward important, order of magnitude arguments
7 WHAT IS GRAVITATIONAL INSTABILITY? ^WHEN H<<R A hydrodynamic instability that arises in rotational;y supported disks when selfgravity wins out over pressure support on small scales, and stabilization due to shear on large scales P Fg Ω (! m (R)) 2 = c 2 s k 2 2 G k + apple 2, Q = c s G = f M H M D r Growth begins at Q=1 in the local approximation, for axisymmetric modes. since H<<R, Md<<M*
8 WHAT IS GRAVITATIONAL from Lau & Bertin 1978 INSTABILITY? ^WHEN H<R Fg P Ω Growth begins at Q>1 in the global approximation
9 Paardekooper 2012, Rice+2014 Kratter+2010 LOCAL VS GLOBAL GI H /R =0.01 These two scales are governed by a different dispersion relations, thus different modes H /R =0.4 H /R =0.10 grow at different values of Q H /R =0.2
10 LOCAL VS GLOBAL GI 1978ApJ L Stochastic disc fragmentation 3295 H /R =0.4 These two H /R = Q <. (94) scales are 3 In other words, keeping the temperature fixed, we only need an ingoverned aof a factor of 3 over the background Q crease in surfaceby density 1 state to form a clump that can resist the shear. Once formed, these p different clumps in general contract on a cooling time-scale (Kratter Mwill disk & Murray-Clay,2011). Their survival depends mainly on if they J = 6m can resist dispersion Mthe? weak shocks that sweep around in gravitoturbulence. Since shock heating is very localized, this makes fragmentation a stochastic process: there will be a large spread in clump survival relations, thus times, until the first lucky clump survives long enough for collapse to proceed. It should be noted that the condition given by equadifferent modes and P.J. Armitage tion (93) is not necessary if the cooling time-scale is comparable to dynamical time-scale. If cooling acts on a dynamical time-scale, growthe at there is nodifferent time for the clump to shear apart before it collapses. H /R =0.10 H /R =0.2 We have observed fragmentation up to β = 7, more than twice values Qtime-scale found by Gammie (2001). The corthe critical of cooling where R0 is the radial distance to the central star and M is its mass. This condition can be recast in terms of the local value of Q: Higher resolution Figure 1. Final state of a full 10 million particle simulation using smoothed cooling with βcool = 8. At this stage (after 6.5 outer rotation periods) the6.disc has settled into in a quasi-steady andsurface there isdensity, no evidence of igure Surface density, terms of thestate initial on a loga- We find that increasing the resolution by a factor of 2 (N x = N y = 2048) leads to easier fragmentation at higher values of β. As an example, we show in Fig. 7 four simulations at β = 9, differing only in the phase (not magnitude) of the initial noise. Two of the discs fragment, one at "t 500 and other at "t 750. The other two discs maintain a steady gravitoturbulent state for the full length of the simulation. This nicely illustrates the stochastic nature of disc fragmentation at high values of β: only in two out of four simulations does a clump survive for long enough for collapse to proceed. It is expected that if the simulations would be continued, Paardekooper 2012, Rice+2014 Downloaded from by g responding maximum value of the stress is α max For larger values of β, the disc remained in a steady, gravitoturbulent state for "t < 1000, with values of α that agree well with equation (3). Kratter+2010
11 From GI to Fragmentation Fragmentation occurs when the instability does not saturate in the linear phase. Saturation typically occurs in one of two ways: mode-mode coupling thermal feedback
12 MODE-MODE COUPLING Interaction of multiple growing modes saturates the amplitude of density perturbations surface density may never get high enough *locally* for collapse, because global modes are triggered at higher Q. global modes provide very efficient angular momentum transport may be important where MRI / disk winds fail FIG. 6.ÈGlobal Fourier amplitudes, C ÈC, plotted as a function of time 1 4 Laughlin, Korchagin, Adams 1996
13 THERMAL FEEDBACK: THE COOLING TIME CRITERION waves/spiral arms generate subsonic shocks, which heat the gas. too much heating, Q>1, self-regulated GI is possible too little heating, Q<1, fragmentation c = 1 c2 s T 4 f( ) since the instability grows on a dynamical time, cooling on a similar timescale is too fast to stave off fragmentation.
14 HOW FAST? WHAT IS Physically: set by optical depth due to dust. It depends on the (effective) EOS ( ) Probably between 8-15 for protoplanetary disks with =7/5 Numerical modelling required
15 Gammie, 2001 Saturation vs fragmentation Kratter+2010a Fragments also occur on scales ~H Most power in gravito-turbulence occurs on scales 1<H<10
16 WHAT ARE THE RIGHT PARAMETERS FOR PROTOSTELLAR AND PROTOPLANETARY DISKS?
17 Kratter & Lodato, in prep H<R accretional heating only including irradiation Conditions in a massive, protostellar disk around a sun-like star T 4 mid = 3 8 f( R)F acc + T 4 h, + T 4 ex F acc = 3 8 Ṁ 2
18 Kratter & Lodato, in prep H<R Conditions in a massive disk around a sun-like star corresponding values of Q and cooling time, between AU it is close enough to give rise to GI
19 H<<R Kratter & Lodato, in prep Conditions for measured Class I disks around sun-like stars Disks that are low enough in mass to operate in the local regime are typically too hot to suffer from GI.
20 HOW DID WE GET HERE? Disk with Q>1 Q = c s G = f M H M D r The outer regions of protostellar disks are dominated by stellar irradiation, which fixes the temperature.
21 HOW DID WE GET HERE? Disk with Q>1 Q = c s G = f M H M D r add mass, raise surface density The outer regions of protostellar disks are dominated by stellar irradiation, which fixes the temperature.
22 HOW DID WE GET HERE? Disk with Q>1 Q = c s G = f M H M D r cool the disk down add mass, raise surface density The outer regions of protostellar disks are dominated by stellar irradiation, which fixes the temperature.
23 HOW DID WE GET HERE? Disk with Q>1 Q = c s G = f M H M D r cool the disk down add mass, raise surface density The outer regions of protostellar disks are dominated by stellar irradiation, which fixes the temperature.
24 HOW DID WE GET HERE? Disk with Q>1 Q = c s G = f M H M D r cool the disk down add mass, raise surface density The outer regions of protostellar disks are dominated by stellar irradiation, which fixes the temperature. only under very special circumstances can the disk reach instability by getting colder, rather than by adding mass
25 normalized accretion radius = Ṁin M d 0.1 Low Mass Stars High Mass Stars 0.01 Singles multiples / fragments binary twins? Kratter et al 2010 normalized accretion rate = ṀG c 3 s
26 Fragment mass, zeroth order M frag = 2 H 2 M iso /M isanumericalconstant M iso 4πf H ΣR H r. numericalconstantrep R H = r(m iso /3M ) 1/3, If disks are driven unstable by infall, it can be challenging to avoid isolation mass H/R Kratter et al 2010b Q
27 WHY DO FRAGMENTS GROW IN DISKS WITH INFALL?
28 WHY DO FRAGMENTS GROW IN DISKS WITH INFALL? Ṁ in
29 WHY DO FRAGMENTS GROW IN DISKS WITH INFALL? Ṁ in
30 WHY DO FRAGMENTS GROW IN DISKS WITH INFALL? Ṁ in R hill
31 WHY DO FRAGMENTS GROW IN DISKS WITH INFALL? Ṁ in R hill
32 WHY DO FRAGMENTS GROW IN DISKS WITH INFALL? Ṁ in R hill
33 WHY DO FRAGMENTS GROW IN DISKS WITH INFALL? Ṁ in R hill
34 First order: how massive are fragments? Initial mass estimates all scale with H 2 Fragments that are not disrupted can also easily grow from the parent disk Kratter & Lodato, in prep, with data from Kratter+2010,Boley +2010,Forgan & Rice 2013, Young & Clarke 2015
35 First order: how massive are fragments? Initial mass estimates all scale with H 2 Fragments that are not disrupted can also easily grow from the parent disk Kratter & Lodato, in prep, with data from Kratter+2010,Boley +2010,Forgan & Rice 2013, Young & Clarke 2015
36 Choose your own GI adventure! local local (cold, low mass) or global (hotter, higher mass)? global slow or fast slow or fast cooling? cooling? fast slow fast slow
37 Choose your own GI adventure! local local (cold, low mass) or global (hotter, higher mass)? global slow or fast slow or fast cooling? cooling? fast slow fast slow probably a young, compact Class 0
38 Choose your own GI adventure! local local (cold, low mass) or global (hotter, higher mass)? global slow slow or fast cooling? fast slow probably a young, compact Class 0 slow or fast cooling? fast fragment! but destruction/ binary formation likely
39 Choose your own GI adventure! local local (cold, low mass) or global (hotter, higher mass)? global slow slow or fast cooling? fast fragment with extreme mass ratio! you might be a shadowed PPD or an AGN slow probably a young, compact Class 0 slow or fast cooling? fast fragment! but destruction/ binary formation likely
40 Choose your own GI adventure! local local (cold, low mass) or global (hotter, higher mass)? global slow slow or fast cooling? self-regulated GI you might be an AGN! fast fragment with extreme mass ratio! you might be a shadowed PPD or an AGN slow probably a young, compact Class 0 slow or fast cooling? fast fragment! but destruction/ binary formation likely
41 Choose your own GI adventure! local local (cold, low mass) or global (hotter, higher mass)? global slow slow or fast cooling? self-regulated GI you might be an AGN! fast infall fragment with extreme mass ratio! you might be a shadowed PPD or an AGN slow probably a young, compact Class 0 slow or fast cooling? fast fragment! but destruction/ binary formation likely
42 ON THE NEXT INSTALLMENT.FATE OF FRAGMENTS Disruption on few dynamical times Partial or complete disruption due to inward migration Direct collapse / continued growth GI population synthesis, and other ways to make wide orbit planets
Non-ideal hydrodynamics in protoplanetary discs
Non-ideal hydrodynamics in protoplanetary discs Min-Kai Lin Steward Theory Fellow University of Arizona March 15 2016 Example: disc asymmetries Vortices at planetary gap edges (HD142527, Casassus et al.,
More informationIntroduction. Convergence of the fragmentation boundary in self-gravitating discs
Convergence of the fragmentation boundary in self-gravitating discs Collaborators : Phil Armitage - University of Colorado Duncan Forgan- University of St Andrews Sijme-Jan Paardekooper Queen Mary, University
More informationForming Gas-Giants Through Gravitational Instability: 3D Radiation Hydrodynamics Simulations and the Hill Criterion
Forming Gas-Giants Through Gravitational Instability: 3D Radiation Hydrodynamics Simulations and the Hill Criterion Patrick D Rogers & James Wadsley June 15, 2012 Forming Gas-Giants Through Gravitational
More informationGravitational fragmentation of discs can form stars with masses
Gravitational fragmentation of discs can form stars with masses from ~3 M J to ~200 M J (0.2M ) Defining stars, brown dwarfs Stars and planets Objects formed by gravitational instability on a dynamical
More informationLecture 20: Planet formation II. Clues from Exoplanets
Lecture 20: Planet formation II. Clues from Exoplanets 1 Outline Definition of a planet Properties of exoplanets Formation models for exoplanets gravitational instability model core accretion scenario
More informationOrigins of Gas Giant Planets
Origins of Gas Giant Planets Ruth Murray-Clay Harvard-Smithsonian Center for Astrophysics Image Credit: NASA Graduate Students Piso Tripathi Dawson Undergraduates Wolff Lau Alpert Mukherjee Wolansky Jackson
More informationStellar Birth. Stellar Formation. A. Interstellar Clouds. 1b. What is the stuff. Astrophysics: Stellar Evolution. A. Interstellar Clouds (Nebulae)
Astrophysics: Stellar Evolution 1 Stellar Birth Stellar Formation A. Interstellar Clouds (Nebulae) B. Protostellar Clouds 2 C. Protostars Dr. Bill Pezzaglia Updated: 10/02/2006 A. Interstellar Clouds 1.
More informationLecture 6: Protostellar Accretion
Lecture 6: Protostellar Accretion Richard Alexander, 23rd March 2009 The angular momentum problem When we try to understand how young stars form, the obvious question to ask is how do young stars accrete
More informationDiscs or Disks? A review of circumstellar discs. Ken Rice Institute for Astronomy University of Edinburgh. 6/18/12 Labyrinth of Star Formation
Discs or Disks? A review of circumstellar discs Ken Rice Institute for Astronomy University of Edinburgh Circumstellar accretion discs Formed during the gravitational collapse of a gaseous molecular cloud
More informationDr G. I. Ogilvie Lent Term 2005 INTRODUCTION
Accretion Discs Mathematical Tripos, Part III Dr G. I. Ogilvie Lent Term 2005 INTRODUCTION 0.1. Accretion If a particle of mass m falls from infinity and comes to rest on the surface of a star of mass
More informationCircumbinary Planets and Assembly of Protoplanetary Disks
Circumbinary Planets and Assembly of Protoplanetary Disks Dong Lai Cornell University with Francois Foucart (CITA) Aspen Exoplanets in the Kepler Era, 2/14/2013 Transiting Circumbinary Planets from Kepler
More informationarxiv: v1 [astro-ph.sr] 29 Nov 2011
Draft version November 2, 2018 Preprint typeset using L A TEX style emulateapj v. 08/22/09 CHALLENGES IN FORMING PLANETS BY GRAVITATIONAL INSTABILITY: DISK IRRADIATION AND CLUMP MIGRATION, ACCRETION &
More informationUnstable Disks: Gas and Stars via an analytic model
Unstable Disks: Gas and Stars via an analytic model Marcello Cacciato in collaboration with Avishai Dekel Minerva Fellow @ HUJI Theoretical studies and hydrodynamical cosmological simulations have shown
More informationBROWN DWARF FORMATION BY DISC FRAGMENTATION
BROWN DWARF FORMATION BY DISC FRAGMENTATION Ant Whitworth, Cardiff Dimitri Stamatellos, Cardiff plus Steffi Walch, Cardiff Murat Kaplan, Cardiff Simon Goodwin, Sheffield David Hubber, Sheffield Richard
More informationStar formation. Protostellar accretion disks
Star formation Protostellar accretion disks Summary of previous lectures and goal for today Collapse Protostars - main accretion phase - not visible in optical (dust envelope) Pre-main-sequence phase -
More informationEXOPLANET LECTURE PLANET FORMATION. Dr. Judit Szulagyi - ETH Fellow
EXOPLANET LECTURE PLANET FORMATION Dr. Judit Szulagyi - ETH Fellow (judits@ethz.ch) I. YOUNG STELLAR OBJECTS AND THEIR DISKS (YSOs) Star Formation Young stars born in 10 4 10 6 M Sun Giant Molecular Clouds.
More informationLast time: looked at proton-proton chain to convert Hydrogen into Helium, releases energy.
Last time: looked at proton-proton chain to convert Hydrogen into Helium, releases energy. Last time: looked at proton-proton chain to convert Hydrogen into Helium, releases energy. Fusion rate ~ Temperature
More informationChapter 16 Lecture. The Cosmic Perspective Seventh Edition. Star Birth Pearson Education, Inc.
Chapter 16 Lecture The Cosmic Perspective Seventh Edition Star Birth 2014 Pearson Education, Inc. Star Birth The dust and gas between the star in our galaxy is referred to as the Interstellar medium (ISM).
More informationLecture 21 Formation of Stars November 15, 2017
Lecture 21 Formation of Stars November 15, 2017 1 2 Birth of Stars Stars originally condense out of a COLD, interstellar cloud composed of H and He + trace elements. cloud breaks into clumps (gravity)
More informationMigration. Phil Armitage (University of Colorado) 4Migration regimes 4Time scale for massive planet formation 4Observational signatures
Phil Armitage (University of Colorado) Migration 4Migration regimes 4Time scale for massive planet formation 4Observational signatures Ken Rice (UC Riverside) Dimitri Veras (Colorado) + Mario Livio, Steve
More informationFrom Massive Cores to Massive Stars
From Massive Cores to Massive Stars Mark Krumholz Princeton University / UC Santa Cruz Collaborators: Richard Klein, Christopher McKee (UC Berkeley) Kaitlin Kratter, Christopher Matzner (U. Toronto) Jonathan
More informationBrown Dwarf Formation from Disk Fragmentation and Ejection
Brown Dwarf Formation from Disk Fragmentation and Ejection Shantanu Basu Western University, London, Ontario, Canada Collaborator: Eduard Vorobyov (University of Vienna) 50 years of Brown Dwarfs Ringberg
More informationViolent Disk Instability at z=1-4 Outflows; Clump Evolution; Compact Spheroids
Violent Disk Instability at z=1-4 Outflows; Clump Evolution; Compact Spheroids Avishai Dekel The Hebrew University of Jerusalem Santa Cruz, August 2013 stars 5 kpc Outline 1. Inflows and Outflows 2. Evolution
More informationImplications of protostellar disk fragmentation
Implications of protostellar disk fragmentation Eduard Vorobyov: The Institute of Astronomy, The University of Vienna, Vienna, Austria Collaborators: Shantanu Basu, The University of Western Ontario, Canada
More informationarxiv:astro-ph/ v1 8 Mar 2006
Gravitational Instabilities in Gaseous Protoplanetary Disks and Implications for Giant Planet Formation Richard H. Durisen Indiana University Alan P. Boss Carnegie Institution of Washington arxiv:astro-ph/0603179v1
More informationPlanet Formation. XIII Ciclo de Cursos Especiais
Planet Formation Outline 1. Observations of planetary systems 2. Protoplanetary disks 3. Formation of planetesimals (km-scale bodies) 4. Formation of terrestrial and giant planets 5. Evolution and stability
More informationThe Magnetorotational Instability
The Magnetorotational Instability Nick Murphy Harvard-Smithsonian Center for Astrophysics Astronomy 253: Plasma Astrophysics March 10, 2014 These slides are based off of Balbus & Hawley (1991), Hawley
More informationChapter 19 The Origin of the Solar System
Chapter 19 The Origin of the Solar System Early Hypotheses catastrophic hypotheses, e.g., passing star hypothesis: Star passing closely to the the sun tore material out of the sun, from which planets could
More informationTheoretical ideas About Galaxy Wide Star Formation! Star Formation Efficiency!
Theoretical ideas About Galaxy Wide Star Formation Theoretical predictions are that galaxy formation is most efficient near a mass of 10 12 M based on analyses of supernova feedback and gas cooling times
More informationLecture 14: Viscous Accretion Disks. HST: μm image of the A0e star AB Aurigae
Lecture 14: Viscous Accretion Disks HST: 0.2-1 μm image of the A0e star AB Aurigae OB1a (10 Myr) Subgroups in the Orion OB1 Associations OB1b (5 Myr) OB1c (2.5 Myr) OB1d (1 Myr) The Orion OB1 association
More informationGravitational collapse of gas
Gravitational collapse of gas Assume a gas cloud of mass M and diameter D Sound speed for ideal gas is c s = γ P ρ = γ nkt ρ = γ kt m Time for sound wave to cross the cloud t sound = D == D m c s γ kt
More informationCore Accretion at Wide Separations: The Critical Role of Gas
Core Accretion at Wide Separations: The Critical Role of Gas Marois et al. 2008 Ruth Murray-Clay Harvard-Smithsonian Center for Astrophysics Kaitlin Kratter, Hagai Perets, Andrew Youdin Wide separation
More informationThe large-scale magnetic field in protoplanetary disks
The large-scale magnetic field in protoplanetary disks Jérôme Guilet MPA, Garching Max-Planck-Princeton center for plasma physics In collaboration with Gordon Ogilvie (Cambridge) 1/24 Talk outline 1) Impacts
More informationPAPER 57 DYNAMICS OF ASTROPHYSICAL DISCS
MATHEMATICAL TRIPOS Part III Monday, 9 June, 2014 1:30 pm to 3:30 pm PAPER 57 DYNAMICS OF ASTROPHYSICAL DISCS Attempt no more than TWO questions. There are THREE questions in total. The questions carry
More informationAST101 Lecture 13. The Lives of the Stars
AST101 Lecture 13 The Lives of the Stars A Tale of Two Forces: Pressure vs Gravity I. The Formation of Stars Stars form in molecular clouds (part of the interstellar medium) Molecular clouds Cold: temperatures
More informationAST 101 Introduction to Astronomy: Stars & Galaxies
AST 101 Introduction to Astronomy: Stars & Galaxies The H-R Diagram review So far: Stars on Main Sequence (MS) Next: - Pre MS (Star Birth) - Post MS: Giants, Super Giants, White dwarfs Star Birth We start
More informationFrom pebbles to planetesimals and beyond
From pebbles to planetesimals... and beyond (Lund University) Origins of stars and their planetary systems Hamilton, June 2012 1 / 16 Overview of topics Size and time Dust µ m Pebbles cm Planetesimals
More informationRuth Murray-Clay University of California, Santa Barbara
A Diversity of Worlds: Toward a Theoretical Framework for the Structures of Planetary Systems Ruth Murray-Clay University of California, Santa Barbara Strange New Worlds. Slide credit: Scott Gaudi ~1500
More informationEvolution of High Mass stars
Evolution of High Mass stars Neutron Stars A supernova explosion of a M > 8 M Sun star blows away its outer layers. The central core will collapse into a compact object of ~ a few M Sun. Pressure becomes
More informationEvolution of protoplanetary discs
Evolution of protoplanetary discs and why it is important for planet formation Bertram Bitsch Lund Observatory April 2015 Bertram Bitsch (Lund) Evolution of protoplanetary discs April 2015 1 / 41 Observations
More informationDisc-Planet Interactions during Planet Formation
Disc-Planet Interactions during Planet Formation Richard Nelson Queen Mary, University of London Collaborators: Paul Cresswell (QMUL), Martin Ilgner (QMUL), Sebastien Fromang (DAMTP), John Papaloizou (DAMTP),
More informationarxiv: v1 [astro-ph.ep] 13 Jan 2019
MNRAS, 1 21 (217) Preprint 1 January 219 Compiled using MNRAS LATEX style file v3. Nonlinear outcome of gravitational instability in an irradiated protoplanetary disc Shigenobu Hirose, 1 and Ji-Ming Shi
More informationComponents of Galaxies Stars What Properties of Stars are Important for Understanding Galaxies?
Components of Galaxies Stars What Properties of Stars are Important for Understanding Galaxies? Temperature Determines the λ range over which the radiation is emitted Chemical Composition metallicities
More informationStar Cluster Formation
Star Cluster Formation HST Colin Hill Princeton Astrophysics 4 December 2012 Trapezium VLT Outline Star Clusters: Background + Observations The Life of a Cluster - Fragmentation - Feedback Effects - Mass
More informationChapter 11 The Formation and Structure of Stars
Chapter 11 The Formation and Structure of Stars Guidepost The last chapter introduced you to the gas and dust between the stars that are raw material for new stars. Here you will begin putting together
More informationThe Jeans mass as a fundamental measure of self-gravitating disc fragmentation and initial fragment mass
Mon. Not. R. Astron. Soc. 417, 1928 1937 2011) doi:10.1111/j.1365-2966.2011.19380.x The Jeans mass as a fundamental measure of self-gravitating disc fragmentation and initial fragment mass Duncan Forgan
More informationF. Marzari, Dept. Physics, Padova Univ. Planetary migration
F. Marzari, Dept. Physics, Padova Univ. Planetary migration Standard model of planet formation based on Solar system exploration Small semimajor axes Large eccentricities The standard model Protostar +Disk
More informationAccretion Disks. Review: Stellar Remnats. Lecture 12: Black Holes & the Milky Way A2020 Prof. Tom Megeath 2/25/10. Review: Creating Stellar Remnants
Lecture 12: Black Holes & the Milky Way A2020 Prof. Tom Megeath Review: Creating Stellar Remnants Binaries may be destroyed in white dwarf supernova Binaries be converted into black holes Review: Stellar
More informationThe Evolution of Close Binaries
The Evolution of Close Binaries Philipp Podsiadlowski (Oxford) The case of RS Ophiuchi as a test of binary stellar evolution as a potential Type Ia supernova (SN Ia) progenitor I. Testing Binary Evolution:
More informationGlobal gravitational instabilities in discs with infall
Mon. Not. R. Astron. Soc. 413, 423 433 (2011) doi:10.1111/j.1365-2966.2010.18146.x Global gravitational instabilities in discs with infall D. Harsono, 1 R. D. Alexander 1,2 and Y. Levin 1,3,4 1 Leiden
More informationG. Bertin Dipartimento di Fisica Universita degli Studi di Milano Bertinoro, May 7-12, 2006
DYNAMICS OF SPIRAL GALAXIES G. Bertin Dipartimento di Fisica Universita degli Studi di Milano Bertinoro, May 7-12, 2006 OUTLINE PART I Some interesting topics in the dynamics of spiral galaxies ; morphology
More informationThe Competitive Accretion Debate
The Competitive Accretion Debate 1,2 Paul C. Clark 2 Ralf S. Klessen 3 Ian A. Bonnell 3 Rowan J. Smith 1 KITP 2 University of Heidelberg 3 University of St Andrews What is CA and how does it work? Theory
More informationPlanetary System Stability and Evolution. N. Jeremy Kasdin Princeton University
Planetary System Stability and Evolution N. Jeremy Kasdin Princeton University (Lots of help from Eric Ford, Florida and Robert Vanderbei, Princeton) KISS Exoplanet Workshop 10 November 2009 Motivation
More informationOther stellar types. Open and globular clusters: chemical compositions
Other stellar types Some clusters have hotter stars than we find in the solar neighbourhood -- O, B, A stars -- as well as F stars, and cooler stars (G, K, M) Hence we can establish intrinsic values (M
More informationSelected Topics in Plasma Astrophysics
Selected Topics in Plasma Astrophysics Range of Astrophysical Plasmas and Relevant Techniques Stellar Winds (Lecture I) Thermal, Radiation, and Magneto-Rotational Driven Winds Connections to Other Areas
More informationThe Life Cycles of Stars. Dr. Jim Lochner, NASA/GSFC
The Life Cycles of Stars Dr. Jim Lochner, NASA/GSFC Twinkle, Twinkle, Little Star... A constellation is an apparent group of stars originally named for mythical characters. The sky contains 88 constellations.
More informationThe Birth Of Stars. How do stars form from the interstellar medium Where does star formation take place How do we induce star formation
Goals: The Birth Of Stars How do stars form from the interstellar medium Where does star formation take place How do we induce star formation Interstellar Medium Gas and dust between stars is the interstellar
More informationIV From cores to stars
IV From cores to stars 4.0 The Jeans condition When the supporting pressure in a region is not able to hold that region up against gravitational collapse it is said to be Jeans unstable. The Jeans length
More informationProtoplanetary Disks: Gas Dynamics
Spring School on Planet Formation, IASTU, Beijing, 05/2014 Protoplanetary Disks: Gas Dynamics Xuening Bai Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics Topics to be
More informationPlanet disk interaction
Planet disk interaction Wilhelm Kley Institut für Astronomie & Astrophysik & Kepler Center for Astro and Particle Physics Tübingen March 2015 4. Planet-Disk: Organisation Lecture overview: 4.1 Introduction
More informationReview: HR Diagram. Label A, B, C respectively
Stellar Evolution Review: HR Diagram Label A, B, C respectively A C B a) A: White dwarfs, B: Giants, C: Main sequence b) A: Main sequence, B: Giants, C: White dwarfs c) A: Main sequence, B: White Dwarfs,
More informationFormation Mechanisms of Brown Dwarfs: Observations & Theories. Dan Li April 2009
Formation Mechanisms of Brown Dwarfs: Observations & Theories Dan Li April 2009 What is brown dwarf (BD)? BD Mass : upper-limit ~ 0.075 M lower-limit ~ 0.013 M (?) Differences between BD and giant planet:
More informationFormation of the Solar System Chapter 8
Formation of the Solar System Chapter 8 To understand the formation of the solar system one has to apply concepts such as: Conservation of angular momentum Conservation of energy The theory of the formation
More informationNumerical Cosmology & Galaxy Formation
Numerical Cosmology & Galaxy Formation Lecture 13: Example simulations Isolated galaxies, mergers & zooms Benjamin Moster 1 Outline of the lecture course Lecture 1: Motivation & Historical Overview Lecture
More informationWhere do Stars Form?
Where do Stars Form? Coldest spots in the galaxy: T ~ 10 K Composition: Mainly molecular hydrogen 1% dust EGGs = Evaporating Gaseous Globules ftp://ftp.hq.nasa.gov/pub/pao/pressrel/1995/95-190.txt Slide
More informationPlanet Formation. lecture by Roy van Boekel (MPIA) suggested reading: LECTURE NOTES ON THE FORMATION AND EARLY EVOLUTION OF PLANETARY SYSTEMS
Planet Formation lecture by Roy van Boekel (MPIA) suggested reading: LECTURE NOTES ON THE FORMATION AND EARLY EVOLUTION OF PLANETARY SYSTEMS by Philip J. Armitage http://arxiv.org/abs/astro-ph/0701485
More informationPlanet formation in protoplanetary disks. Dmitry Semenov Max Planck Institute for Astronomy Heidelberg, Germany
Planet formation in protoplanetary disks Dmitry Semenov Max Planck Institute for Astronomy Heidelberg, Germany Suggested literature "Protoplanetary Dust" (2010), eds. D. Apai & D. Lauretta, CUP "Protostars
More informationDead zones in protoplanetary discs
Dead zones in protoplanetary discs Mark Wardle Macquarie University Raquel Salmeron (ANU) BP Pandey (Macquarie) Protoplanetary discs Magnetic fields Dead zones MRI and diffusion Modification to dead zones
More informationRADIATION FROM ACCRETION ONTO BLACK HOLES
RADIATION FROM ACCRETION ONTO BLACK HOLES Accretion via MHD Turbulence: Themes Replacing dimensional analysis with physics MRI stirs turbulence; correlated by orbital shear; dissipation heats gas; gas
More informationN-body Dynamics in Stellar Clusters Embedded in Gas
N-body Dynamics in Stellar Clusters Embedded in Gas Matthew Bate, University of Exeter Kurosawa, Harries, Bate & Symington (2004) Collaborators: Ian Bonnell, St Andrews Volker Bromm, Texas Star Formation
More informationExoplanets: a dynamic field
Exoplanets: a dynamic field Alexander James Mustill Amy Bonsor, Melvyn B. Davies, Boris Gänsicke, Anders Johansen, Dimitri Veras, Eva Villaver The (transiting) exoplanet population Solar System Hot Jupiters:
More informationMotivation Q: WHY IS STAR FORMATION SO INEFFICIENT? Ṁ M gas / dyn. Log SFR. Kennicutt Log. gas / dyn
Motivation Q: WHY IS STAR FORMATION SO INEFFICIENT? Ṁ 0.017 M gas / dyn Log SFR Kennicutt 1998 Log gas / dyn Motivation Q: WHY IS STAR FORMATION SO INEFFICIENT? Moster 2009 No Feedback 10% of baryons Log(
More informationwhile the Planck mean opacity is defined by
PtII Astrophysics Lent, 2016 Physics of Astrophysics Example sheet 4 Radiation physics and feedback 1. Show that the recombination timescale for an ionised plasma of number density n is t rec 1/αn where
More informationStar Formation. Stellar Birth
Star Formation Lecture 12 Stellar Birth Since stars don t live forever, then they must be born somewhere and at some time in the past. How does this happen? And when stars are born, so are planets! 1 Molecular
More informationDefinitions. Stars: M>0.07M s Burn H. Brown dwarfs: M<0.07M s No Burning. Planets No Burning. Dwarf planets. cosmic composition (H+He)
Definitions Stars: M>0.07M s Burn H cosmic composition (H+He) Brown dwarfs: M
More informationVortices in accretion discs: formation process and dynamical evolution
Vortices in accretion discs: formation process and dynamical evolution Geoffroy Lesur DAMTP (Cambridge UK) LAOG (Grenoble) John Papaloizou Sijme-Jan Paardekooper Giant vortex in Naruto straight (Japan)
More informationAstronomy Notes Chapter 13.notebook. April 11, 2014
All stars begin life in a similar way the only difference is in the rate at which they move through the various stages (depends on the star's mass). A star's fate also depends on its mass: 1) Low Mass
More informationGuiding Questions. The Birth of Stars
Guiding Questions The Birth of Stars 1 1. Why do astronomers think that stars evolve (bad use of term this is about the birth, life and death of stars and that is NOT evolution)? 2. What kind of matter
More informationStellar Evolution: Outline
Stellar Evolution: Outline Interstellar Medium (dust) Hydrogen and Helium Small amounts of Carbon Dioxide (makes it easier to detect) Massive amounts of material between 100,000 and 10,000,000 solar masses
More informationStellar evolution Part I of III Star formation
Stellar evolution Part I of III Star formation The interstellar medium (ISM) The space between the stars is not completely empty, but filled with very dilute gas and dust, producing some of the most beautiful
More informationGalaxy Formation: Overview
Galaxy Formation: Overview Houjun Mo March 30, 2004 The basic picture Formation of dark matter halos. Gas cooling in dark matter halos Star formation in cold gas Evolution of the stellar populaion Metal
More informationRemember from Stefan-Boltzmann that 4 2 4
Lecture 17 Review Most stars lie on the Main sequence of an H&R diagram including the Sun, Sirius, Procyon, Spica, and Proxima Centauri. This figure is a plot of logl versus logt. The main sequence is
More informationThe Life Cycles of Stars. Modified from Information provided by: Dr. Jim Lochner, NASA/GSFC
The Life Cycles of Stars Modified from Information provided by: Dr. Jim Lochner, NASA/GSFC Twinkle, Twinkle, Little Star... What do you see? How I Wonder What You Are... Stars have: Different Colors -
More informationStars and their properties: (Chapters 11 and 12)
Stars and their properties: (Chapters 11 and 12) To classify stars we determine the following properties for stars: 1. Distance : Needed to determine how much energy stars produce and radiate away by using
More informationStar formation near Sgr A*
Star formation near Sgr A* Sergei Nayakshin University of Leicester Plan Stay away from the S-stars (Schoedel et al. 02, Ghez et al 03) of the inner arcsecond (see T. Alexander talk) Sgr A* young stars
More informationKozai-Lidov oscillations
Kozai-Lidov oscillations Kozai (1962 - asteroids); Lidov (1962 - artificial satellites) arise most simply in restricted three-body problem (two massive bodies on a Kepler orbit + a test particle) e.g.,
More informationThe Migration of Giant Planets in Massive Protoplanetary Discs
The Migration of Giant Planets in Massive Protoplanetary Discs Kate E. M. Robinson A thesis submitted in partial fulfilment for the requirements for the degree of Master of Science at the University of
More informationDynamics of Astrophysical Discs
Dynamics of Astrophysical Discs 16 lectures, 3 example classes http://www.damtp.cam.ac.uk/user/hl278/dad.html Henrik Latter e-mail: hl278@cam.ac.uk 16 lectures Tu. Th. 10 Course Outline Office: F1.19 hl278@cam.
More informationTheory of star formation
Theory of star formation Monday 8th 17.15 18.00 Molecular clouds and star formation: Introduction Tuesday 9th 13.15 14.00 Molecular clouds: structure, physics, and chemistry 16.00 16.45 Cloud cores: statistics
More informationLecture Outlines. Chapter 15. Astronomy Today 7th Edition Chaisson/McMillan Pearson Education, Inc.
Lecture Outlines Chapter 15 Astronomy Today 7th Edition Chaisson/McMillan Chapter 15 The Formation of Planetary Systems Units of Chapter 15 15.1 Modeling Planet Formation 15.2 Terrestrial and Jovian Planets
More information3/1/18 LETTER. Instructors: Jim Cordes & Shami Chatterjee. Reading: as indicated in Syllabus on web
Astro 2299 The Search for Life in the Universe Lecture 9 Last time: Star formation Formation of protostars and planetary systems This time A few things about the epoch of reionization and free fall times
More information18. Stellar Birth. Initiation of Star Formation. The Orion Nebula: A Close-Up View. Interstellar Gas & Dust in Our Galaxy
18. Stellar Birth Star observations & theories aid understanding Interstellar gas & dust in our galaxy Protostars form in cold, dark nebulae Protostars evolve into main-sequence stars Protostars both gain
More informationPLANETARY MIGRATION A. CRIDA
PLANETARY MIGRATION A. CRIDA (the migration of Jupiter carrying its satellites. Alegory.) 1 INTRODUCTION A planet orbiting in a protoplanetary disk launches a one-armed, spiral wake. p star planet Orange
More informationGuiding Questions. Stellar Evolution. Stars Evolve. Interstellar Medium and Nebulae
Guiding Questions Stellar Evolution 1. Why do astronomers think that stars evolve? 2. What kind of matter exists in the spaces between the stars? 3. What steps are involved in forming a star like the Sun?
More informationHow inner planetary systems relate to inner and outer debris belts. Mark Wyatt Institute of Astronomy, University of Cambridge
How inner planetary systems relate to inner and outer debris belts Mark Wyatt Institute of Astronomy, University of Cambridge The Solar System s outer and inner debris belts Outer debris: Kuiper belt Inner
More informationThe Solar Nebula Theory
Reading: Chap. 21, Sect.21.1, 21.3 Final Exam: Tuesday, December 12; 4:30-6:30PM Homework 10: Due in recitation Dec. 1,4 Astro 120 Fall 2017: Lecture 25 page 1 Astro 120 Fall 2017: Lecture 25 page 2 The
More informationFormation Process of the Circumstellar Disk: Long-term Simulations in the Main Accretion Phase of Star Formation
Formation Process of the Circumstellar Disk: Long-term Simulations in the Main Accretion Phase of Star Formation Masahiro N. Machida 1, Shu-ichiro Inutsuka 2, and Tomoaki Matsumoto 3 ABSTRACT The formation
More informationACTIVE GALACTIC NUCLEI: FROM THE CENTRAL BLACK HOLE TO THE GALACTIC ENVIRONMENT
Julian H. Krolik ACTIVE GALACTIC NUCLEI: FROM THE CENTRAL BLACK HOLE TO THE GALACTIC ENVIRONMENT PRINCETON UNIVERSITY PRESS Princeton, New Jersey Preface Guide for Readers xv xix 1. What Are Active Galactic
More informationAccretion Mechanisms
Massive Protostars Accretion Mechanism Debate Protostellar Evolution: - Radiative stability - Deuterium shell burning - Contraction and Hydrogen Ignition Stahler & Palla (2004): Section 11.4 Accretion
More informationAccretion disks. AGN-7:HR-2007 p. 1. AGN-7:HR-2007 p. 2
Accretion disks AGN-7:HR-2007 p. 1 AGN-7:HR-2007 p. 2 1 Quantitative overview Gas orbits in nearly circular fashion Each gas element has a small inward motion due to viscous torques, resulting in an outward
More information