The Origins of Solar Systems. Colin M c Nally

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1 The Origins of Solar Systems Colin M c Nally

2 Introduction 1 In the Beginning Galaxy ISM Composition Molecular Clouds Star Formation Angular Momentum Electromagnetism 2 Protoplanetary Disks History Observations Disk Processes Outflows 3 The First Solids Composition

3 Motivation Solar Systems are ubiquitous 787 extrasolar planetary systems 1039 extrasolar planets uniquely identified

4 Motivation Video at:

5 In the Beginning Galaxy A Galaxy (Andromeda)

6 In the Beginning Galaxy NGC 2403 Left: Neutral Hydrogen Gas Right: Visible Light

7 In the Beginning ISM The Context of Star Formation: Interstellar Medium (ISM)

8 In the Beginning Composition What it is made of? The Sun is roughly representative of the universe today: Element By Atom By Mass Hydrogen 91.2 % 71.0 % Helium 8.7 % 27.1 % Oxygen % 0.97 % Carbon % 0.40 % Nitrogen % % Silicon % % Magnesium % % Neon % % Iron % 0.14 % Sulfur % %

9 In the Beginning Composition Major Phases of the ISM The important parts of the Interstellar Medium: Volume Temperature atoms/cm 3 Warm Ionized Medium 20 50% 8000 K Warn Neutral Medium 10 20% K Cold Neutral Medium 1 5% K Molecular Clouds < 1% K Ionized - Hydrogen ionized (a gas of electrons and protons) Neutral - Hydrogen atoms with an electron note the split between warm and cold Molecular - Hydrogen formed into H 2

10 In the Beginning Molecular Clouds Molecular Clouds - Barnard 68

11 In the Beginning Molecular Clouds Narayanan et al., 2008,ApJS, 177, 341

12 In the Beginning Star Formation Overview See:

13 In the Beginning Star Formation Collapse What makes a cloud collapse? Gravity How fast does this happen? the free fall time What holds a cloud up? gas pressure How does gas pressure react? Through sound waves How fast can pressure react to hold a could up? sound wave crossing time Collapse when: sound crossing time > free fall time This is dominated by the temperature of the gas.

14 In the Beginning Star Formation How is this this tenuous gas a fluid? What is Pressure? Gas Air in this room Interstellar Medium Average Distance Between Collisions cm (70 nm) 100 AU (100 times earth-sun distance)

size rotation speed Two important consequences: Collapse

15 In the Beginning Angular Momentum Conservation of Angular Momentum Angular momentum must be conserved during collapse size rotation speed Two important consequences: Collapse halts when centrifugal force balances gravity Collapsing gas forms a disk

16 In the Beginning Angular Momentum Angular Momentum Transport If gas forms into a disk and keeps the same angular momentum, it would just stay there. only the gas with very low angular momentum would end up as part of the star. Need to exchange angular momentum between parcels of gas. Two directions: Out Up

17 In the Beginning Electromagnetism What Electromagnetism Has to Do With It Ionized gas has separate positive and negative electrical charges Electricity and Magnetism moving an electrical charge induces a magnetic field moving a magnetic field line generates an electric current The induced field or current acts to resist the change. Ionized gas is only free to move along the direction of the magnetic field lines. Caveat: This only applies if the electrical charges (electrons mainly) are totally free to move, if they have any trouble moving (If they collide with other particles) then magnetic field lines just drag on the gas.

18 Protoplanetary Disks History Historical Conceptions Kant-Laplace Nebular Hypothesis Problem with angular momentum von Weizsacker Vortices collect solids

19 Protoplanetary Disks Observations How we Know Stars have Disks Nearby : Seeing the disk block the star Further away, and obscured: Light reflected off the disk

20 Protoplanetary Disks Observations Light Reflected off the Disk

21 Protoplanetary Disks Observations Structure of a Protoplanetary Disk

22 Protoplanetary Disks Disk Processes How we Know Disks are Working See:

23 Protoplanetary Disks Disk Processes Gravity Makes Disks Work Video:

24 Protoplanetary Disks Disk Processes Magnetic Fields Make Disks Work Video: Movie (Case II-low)

X-rays collisional ionization at T > 10 3 K (r < 1 AU), MRI turbulent resistive quenching of MRI,

25 Protoplanetary Disks Disk Processes Turbulence Regimes Cool, dense protoplanetary disks are not obviously ionized dead zone non-thermal ionization of full disk column cosmic rays? X-rays collisional ionization at T > 10 3 K (r < 1 AU), MRI turbulent resistive quenching of MRI, suppressed angular momentum transport MRI-active surface layer ambipolar diffusion dominates Armitage 2011 Hirose & Turner 2011

26 Protoplanetary Disks Outflows Jets and Winds HH30

27 Machida & Hosakawa arxiv: The Origins of Solar Systems Protoplanetary Disks Outflows

28 The First Solids Composition Condensing Dust

29 The First Solids Composition What elements go where? Goldschmidt Classification

30 The First Solids Composition Kinds of Dust What we know, we know from Meteorites: Dust from the ISM - Presolar grains Highest temperature condensates - Calcium Aluminum Rich Inclusions CAIs First things resembling common rocks - silicate gains and chondrules Organic matter (things with Carbon) Ices (what makes these different from the above?)

31 The First Solids Composition Presolar Grains Dust which condensed around some other star and ejected back to the molecular cloud, most likely near the end of the life of a massive star. Difficulty: Picking them out from locally produced dust

32 The First Solids Composition CAIs: Calcium-Aluminum-rich Inclusions Made of the Calcium-Aluminum rich minerals which condense and survive at highest temperatures.

33 Red: Magnesium, Green: Calcium, Blue: Aluminum The Origins of Solar Systems The First Solids Composition Silicate Grains and Chondrules

34 The First Solids Composition Organics - Things with Carbon Orgieul, Wet and soft when found

35 The First Solids Composition Ices Water H 2 O Carbon Monoxide CO Ammonia NH 4

of Solar Systems tially, the sharp change in the partial pressure of water vapor tothe Origins The First Solids across the snow line results in a net flux of water molecules ent Ice Lines outward in

36 of Solar Systems tially, the sharp change in the partial pressure of water vapor tothe Origins The First Solids across the snow line results in a net flux of water molecules ent Ice Lines outward in the disk. However, this radial cold finger effect of likely balanced by the inward migration of icy bodies, as uesices is and Snow Lines discussed in Salyk et al. (2008) and Ciesla (2009). io, ept 10 gas ed m. ns, re, gth at, ey ce, tiels ers be ue

37 The First Solids Ice Lines Ices and Snow Lines Carbon Monoxide (CO) snow line in TW Hydrae disk Continuum: overall millimeter radio image of disk CO: image of CO gas N 2 H + : image of N 2 H + gas, which is rapidly destroyed if any CO gas is present

38 The First Solids Extrasolar Do we know if other solar systems are similar? Some evidence - Polluted White Dwarfs In the end of the life of a solar system, we see a disk of rocky material and extra elements in the remnant of the star Elementally, this material is reasonably similar to asteroids and meteorites

39 The First Solids Chronology Chronology Ages for some meteorite samples Our solar system is about years old. The main events in forming it took about years Components on meteorites with highest condensation temperatures appear to be oldest

40 Building Up Solids Dust Balls In a cloud of dust and gas, one way to make something is to stick a bunch of dust together. How sticky are rocks?

41 Building Up Solids Mechanical Issues in Assembling Solids

42 Building Up Solids Mechanical Issues in Assembling Solids Video: ormel/movies/zsometal2010-mass-vs-phi-mmsn.mpg

43 Building Up Gas Gas Balls Video:

44 Building Up Gas Gas and Solids Growing Together - Core Accreting Gas Video: olives/index.php?id=res

45 Building Up Gas and Solids Gas and Solids Growing Together - Streaming Instability

46 Building Up Gas and Solids Gas and Solids Growing Together - Streaming Instability Video: ajohan/download/mov/streaming3d t1.0 e0.2.mpg

47 Building Up Gas and Solids Gas and Solids Growing Together - Streaming Instability Video: ajohan/download/mov/hires256.mpg

48 The Variety of Systems Migration and Scattering Migration Video:

49 The Variety of Systems Migration and Scattering Scattering Video: r-ktgm

50 Conclusion And all that, put together, must make: Video at:

51 Conclusion The Important Things Gas + Gravity + Magnetic fields Angular Momentum Conservation Angular Momentum Transport Solar Composition - what elements are more abundant What Elements Condense When - Calcium-aluminum rich, rocky, others, ice Kinds of Dust - Rocky or Icey Rocks are not very sticky. Gas and dust work together. Once they form, planets can move about quite a bit.

Chapter 8 Lecture. The Cosmic Perspective Seventh Edition. Formation of the Solar System

Chapter 8 Lecture. The Cosmic Perspective Seventh Edition. Formation of the Solar System Chapter 8 Lecture The Cosmic Perspective Seventh Edition Formation of the Solar System Formation of the Solar System 8.1 The Search for Origins Our goals for learning: Develop a theory of solar system