1. Upcoming Classes Phys 1830 Lecture 21 Our Solar System
Solar System Formation
Second Term Test Friday Mar 6.
Covers material after previous test (pseudo-cummulative).
Topics from “how images are made” (lecture 11) through “computer simulations” (today).
Check material online for test information.
ALL NOTES COPYRIGHT JAYANNE ENGLISH
No iclickers today – time given to animations and simulations. Instead please ask questions as we go along.

2. on tests, quizzes, exams, or midterms
Cheating ...
on tests, quizzes, exams, or midterms
Cheating can be spontaneous or premeditated.
You are also cheating if you allow others to look at your exam.
The Faculty of Science values academic Integrity. Cheating will not be tolerated by the Faculty of Science.
Penalties may include a minimum of:
zero in the assignment,
F-DISC in the course,
a notation written on your transcript, and/or
suspension from courses in the department or the Faculty of Science for one year.

3. Common examples of academic dishonesty that occur every term:
A student brings a calculator to the final exam. The calculator is allowed by the instructor, but the calculator cover is forbidden.
An invigilator discovers the notes and the incident is forwarded to the department Head or the Associate Dean. An act of academic dishonesty has occurred regardless of whether the notes are used by you during the exam.
Also when handing in materials you write on your exam materials near other students answer sheets this provides an opportunity for academic dishonesty.
What are the consequences of the penalties?
They may slow down the progression of your degree, costing you time and money.
They may be visible to potential employers, professional school applications, or graduate schools.
They may affect your student visa eligibility for a year or more.
Protect yourself:
Do not bring unauthorized material into the exam (e. g. notes, cell phone, calculator cover).
Resist opportunities to collaborate inappropriately or look at someone else’s paper.
If you suspect someone looking over your shoulder … Cover your paper; ask to be moved to another seat; alert the invigilator.
Review the online tutorials available through Student Advocacy:
umanitoba.ca/student/resource/student_advocacy/AI-and-Student-Conduct-Tutorials.html

4. How DO You Create a Universe?
Assumptions
Cosmological Model + Parameters
Simulation Method
Astronomical Society of Victoria: Computational Cosmology 2006

5. From this…
observations!
This is the WMAP observations of temperature fluctuations in the cosmic microwave background radiation (CMB). Note that the emission from our Milky Way makes fluctuations along the “equator” of this map uncertain.
As universe expands and cools, small primordial density fluctuations are amplified by gravity

6. … to this Treat dark matter & atoms as collection of points.
observations!
Abell Cluster (HST)

7. Cosmological Simulation
Parameters: Dark matter, etc.; number of particles, time steps, etc.
Model: Apply Newton’s law of Gravity
3) Simulation Method: the N-Body Simulation

8. N*(N-1) = 13*12 = 156 CALCULATIONS
N-Body Solution i
(N-1) = 12 FORCE PAIRS j
N =13 particles
N*(N-1) = 13*12 = 156 CALCULATIONS

9. N-Body Simulations N-bodies interacting under mutual gravitation
Generate initial distribution of positions and velocities
Calculate the forces between particles
Update the position and velocity of each particle
Repeat steps 2 and 3

10. Resolution is the Name of the Game
Ideal:
N = 100 billion stars in a galaxy
At least one simulation particle per star
Current:
Millennium Simulation (MS)
N = 10 billion particles in a box
MS-II focuses on smaller volume

11. 0.21 Gyr after Big Bang

12. 1 Gyr after Big Bang

13. ~5 Gyr after Big Bang

14. 13.6 Gyr after Big Bang  now

15. Visualization: Computer Simulations
Simulations are part of the theoretical component of the method of science.
Generate models that can be compared to observations.
Input information from observations into the simulation.
Evolve the simulation through time.
See if the simulation and observations match.

16. Visualization Input information from observations into the simulation.
Computer Simulations
Visualization
CMBR
Early times MS
Now
Clustering of Galaxies
Large Scale
Structure of the
Universe
CMBR – cosmic microwave background radiation
MS – Millenium Simulation
3. In this case the luminous part of the matter in the universe traces the densest regions of the Dark Matter distribution.
Input information from observations into the simulation.
Evolve the simulation through time.
See if the simulation and observations match.

17. Observations of the Cosmic Web!
Visualization: Example of observations and simulations that are consistent with each other.
Thomas Jarrett (IPAC/Caltech)
The distribution of galaxies is called the Large Scale Structure (LSS) – in the galaxies and cosmology sections of course.
Notice the Milky Way data has been inserted along the equator.
Observations of the Cosmic Web!
Panoramic view of the entire 2MASS near-infrared sky reveals the distribution of galaxies beyond the Milky Way.
Colour coded on velocity (redshift; described later in the course).

18. Assumptions: gas flows like a fluid in a disk Model: gravity
Visualization: Planetary Systems Simulations  Formation of gas giant planets in a protoplanetary disks
Note the spiral structure.
At the other end of the scale spectrum we have models of how systems of planets form.
"Forming Giant Planets via Fragmentation of Protoplanetary Disks"
Lucio Mayer, Tom Quinn, James Wadsley and Joachim Stadel 
Published in SCIENCE, appeared on Nov 29th, 2002.
Assumptions: gas flows like a fluid in a disk
Model:
gravity
this uses equations from hydrodynamics (== the study of forces acting on or exerted by fluids)

19. A numerical simulation
Review
A numerical simulation
is a computer program that evolves a situation through time
uses observations as input
employs physical equations such as Newton’s law of gravity
attempts to match observations
all of the above

20. several hundreds of galaxies in associations
Review
To match observations the end result of a cosmological simulation should have
several hundreds of galaxies in associations
large scale structure throughout the volume modeled
a random distribution of galaxies
a & b
none of the above

21. Test up to here.

22. Animation of the evolution of a planet-forming disk.
Planetary Systems
Numerical models inform animations made for public outreach.
(Stars are in the background.)
This animation shows the evolution of a planet-forming disk around a star. Initially, the young disk is bright and thick with dust, providing raw materials for building planets. In the first 10 million years or so, gaps appear within the disk as newborn planets coalesce out of the dust, clearing out a path. In time, this planetary "debris disk" thins out as gravitational interactions with numerous planets slowly sweep away the dust. Steady pressure from the starlight and solar winds also blows out the dust. After a few billion years, only a thin ring remains in the outermost reaches of the system, a faint echo of the once-brilliant disk.
Animation of the evolution of a planet-forming disk.
Note the dust ring that remains in the outer parts of the system.

23. Is the assumption of a disk a good one?
Planetary Systems:
Orion Nebula is forming several hundred stars. This is an HII region and the pink is H_alpha.
Is the assumption of a disk a good one?
Look where stars are forming to see if there are disks

24. HST image in centre of Orion Nebula.
Planetary Systems:
Note the small suspended “blips”.
HST image in centre of Orion Nebula.

25. Protoplanetary disks are called “proplyds” for short.
Planetary Systems:
Protoplanetary disk is a disk that planets can form within.
(“proto” meaning the earliest stage in a time sequence.)
Protoplanetary disks are called “proplyds” for short.
Dusty disk edge-on to our view.
See radiation from a star forming.

26. The evolving Proplyd is backlit by this emission.
Planetary Systems:
At a later stage young stellar objects in the centre of the disk will emit radiation along their poles.
The evolving Proplyd is backlit by this emission.

27. artist’s illustration
Subaru Telescope
Data
Yes, we see spiral protoplanetary
disks. Indeed some with spiral structure.
left: 2011 and right: 2013
artist’s illustration

28. Do observations also show rings in the outer regions of planetary systems?
(Think of our solar system.)

29. Evidence that a young planet formed in a “disk”!
Planetary Systems:
The box shows where the positions of a bright point source is at 2 different times.
Another planet may be tugging on the dusty belt, since the belt isn’t centred on the star.
Let’s look at other features of this image.
Evidence that a young planet formed in a “disk”!
This is first visible-light image of a dust ring around the nearby, bright young star.
The part of the ring is outside the telescope's view. The ring is tilted obliquely to our line of sight.

30. Planetary Systems:
Image from SOHO satellite.
Coronagraph used to block out the light from the bright star so they could see the faint ring.
A coronagraph uses a disk usually to block our Sun's bright surface producing an artificial eclipse.

31. Some light from the star is still visible in this image.
Planetary Systems
Some light from the star is still visible in this image.
The ring is 133 AU from the star.
The ring’s width is 25 AU.
“The ring is tinted red for image analysis.”
Despite the coronagraph, some light from the star is still visible in this image, as can be seen in the wagon wheel-like spokes that form an inner ring around Fomalhaut.
the ring is 133 astronomical units from the star – comparable to Kuiper Belt which goes from 30 to ~300AU.
the ring's relatively narrow width, 25 astronomical units, indicates that a planet is keeping the ring from spreading out.

32. Planetary Systems: Beta Pictoris
Example of an edge-on disk (warped).
Possibly a giant planet in the inner regions.
Composite image from 2 different IR datasets acquired at the European Southern Observatory.
Hubble Space Telescope’s
Imaging Spectrograph
Beta Pic b is potentially a giant planet at about 8 * Mass of Jupiter at 5 to 10 AU.
This composite image represents the close environment of Beta Pictoris as seen in near infrared light. This very faint environment is revealed after a very careful subtraction of the much brighter stellar halo. The outer part of the image shows the reflected light on the dust disc, as observed in 1996 with the ADONIS instrument on ESO's 3.6 m telescope; the inner part is the innermost part of the system, as seen at 3.6 microns with NACO on the Very Large Telescope. The newly detected source is more than 1000 times fainter than Beta Pictoris, aligned with the disc, at a projected distance of 8 times the Earth-Sun distance. Both parts of the image were obtained on ESO telescopes equipped with adaptive optics. 
Credit: ESO/A.-M. Lagrange et al.

33. Planetary Systems
Simulations start with disks filled with gas and dust.
Observations motivate this initial configuration.

34. Planetary Systems & Disks -- Solar System:
Looking towards the Sun
Looking towards Jupiter
The orbits of the 8 classical planets also indicate that our solar system evolved out of a disk.
The planets’ orbits lay in a narrow plane. Mercury deviates the largest (with only a 7 degree tilt).
They all orbit in the same direction.
Looking from the earth in 2 different directions in the solar system. The planets are distributed in a disk.
As seen from above the earth’s north pole they all orbit counterclockwise.
This is from a nifty simulator from NASA.

35. Assumption that planets form in disks was motivated by observations.
Planetary Systems
Eagle Nebula (M16)
The length of the pillar on the left is about the same distance between our sun and the nearest stars.
Assumption that planets form in disks was motivated by observations.
Is the assumption that the disk is initially very gaseous a good one?

36. Molecular Cloud with “fingers” protruding.
Planetary Systems
Molecular clouds have molecules of hydrogen (2 H atoms share their electrons), carbon monoxide (CO), for example.
Molecular Cloud with “fingers” protruding.
Evaporating Gaseous Globules = EGGs at finger tips.
Each about the size of our solar system.

37. Planetary Systems: Bok Globules in Carina Nebula
Surrounding molecular gas cloud photoevaporates leaving denser globules of rotating gas.
Material in a globule falls towards the centre via gravity.
Simultaneously, due to conservation of angular momentum, a disk consisting mainly of gas and dust forms
--> proplyds.
Photoevaporation: the process in which a cloud is dispersed by the radiation from a nearby hot star. E.g. the bonds of molecules are broken as the photons are absorbed. The resultant atoms of gas also become ionized.
Motion of globule can be due to turbulence in the gas cloud and other factors.
Think of a skater turning, her skirt goes up like a tutu around her waist.
Recall for angular momentum, as the radius decreases the disk is going to spin faster!

38. The central condensation will become a star.
Planetary Systems
This is on our supplemental resource page.
Animation from Swinburne University, Centre for Astronomy and Supercomputing.
Assumption that gas dominates the initial conditions is also founded on observations.
The central condensation will become a star.

39. Planetary System Formation - Observations:
Orion is an example of a dusty, gas cloud forming planetary systems.
Distance is 1,500 ly (460 parsecs).
Proplyds and Bok Globules inform the simulations of star and planet formation.

40. Visualizations: Simulations of Planetary Systems
Observations
Animation based on Simulation
Observations of a planetary system with a ring and planets can be explained by a simulation.
Planetary disk simulations use:
gravity between particles,
gravity between particles and the protostar,
hydrodynamical forces
Note that the planets have cleared their orbits in the simulations.

41. Visualizations: Simulations
Two assumptions for modelling the formation of planets are:
A cloud composed of rocks collapses. This forms a disk. (The biggest rocks are the planets.)
A cloud composed mainly of gas collapses. This forms a disk. (Planets form within this disk.)
Chunks of gas tear off from molecular clouds. Photo-evaporation exposes the planets buried inside these Bok Globules.

42. Extra-solar planets == Exoplanets
More on this after we study our own Solar System

43. The models also have to match features of our own Solar System.
The assumptions in the models of the formation of planetary systems are reasonable since supported by observations of other “solar systems”:
Gas dominates
Disks form
The models also have to match features of our own Solar System.
Why do all the planets orbit in a plane?
Why do they orbit in the same direction?
Why are some planets gaseous and others not?

44. Solar System Overview: Planet Definitions
Classical Planet
Orbits the sun.
Massive enough that is own gravity has caused its shape to be nearly spherical.
It has “cleared the neighbourhood” around its orbit of other bodies.
i.e. either by colliding with (sweeping up) the debris in the disk or by gravitationally kicking the debris out of its path (slingshot effect).
This leaves us with 8 planets.

45. Solar System Overview: Planet Definitions
Dwarf Planet
Orbits the sun.
Massive enough that is own gravity has caused its shape to be spherical.
Is not a satellite of another body.
(Has not cleared its neighbourhood.)
Exact wording is at . See International Astronomical Union Resolution 5A.
Examples:
Pluto
Eris (1.3 * Pluto’s mass)
Ceres (in the asteroid belt)
Objects at Neptune and beyond are called Trans-Neptune Objects (TNO) and those TNO that are similar to Pluto are called plutoids.

46. Solar System Overview:
What do you already know about the classical planets?

47. revolve & rotate in the same direction as other planets?
Solar System Overview: What does the class already know about the classical planets?
For each planet:
revolve & rotate in the same direction as other planets?
primarily composed of rock or of gas? # Earth Masses, # Earth radii
small or large? (i.e. closer to Earth size or Jupiter size?)
in outer region or inner region of solar system?
hot or cold? surface T in Kelvin
Lots of moons?
Any other details are welcome  (eg. Does it have rings? B field?)
If a planet spins in the same direction as its orbit, its spin is called “prograde”. If a planet spins in the opposite direction to its orbital motion, that spin is called “retrograde”.
Do your own research to supplement these powerpoint presentations.
Note about T:
-273 C = 0 K