ASTC25 Astrophysics of Planetary Systems (2025, in-person)
The page you are reading (http://planets.utsc.utoronto.ca/%7Epawel/ASTC25) together with the syllabus and other subpages are the only official source of information on this course. It provides lecture notes, home assignments, prelim. results and other material. Check it regularly.
In addition to this page, Quercus s Media Gallery and a place to submit assignments. It will be used to broadcast messages via email.

Syllabus

This file is an authoritative listing of topics, dates, and locations of lectures, assignments, and exams. Re-download every week!
In case some dates are in disagreement with other files/pages, please notify the lecturer & treat syllabus as the most authoritative. Quercus does not provide updates. Only this page and syllabus explain the rules & details of this course.
Announcements will be sent via Quercus. Please do not send messages from Quercus to us, use your utoronto email.

General information

Welcome to an upper-undergraduate overview of planetary astrophysics at a level appropriate for science students. Topics cover a broad range from orbital mechanics to the dynamics of origin of planets to the discovery of planets outside our solar system (see syllabus).

LEFT: The trajectory shows the known visitor from interstellar called 1I/2017 U1 (Oumuamua). 1I stands for 1st Interstellar. Discovered in 2017 by a military Pan-STARRS 1 telescope in Hawaii at a distance of 0.22 AU from Earth, the small object came from the direction of the constellation Lyra, cruising through interstellar space at 26.33 km/s. Its classification as a small comet vs. asteroid ejected from another planetary system has changed over time: c,a,c,neither. The second, much larger interstellar object, shown by yellow line, is 2I/Borisov comet. It's speed in faraway space (32.2 km/s) and the perihelion distance (2AU) are larger, therefore the deflection angle after flyby is much smaller than 1I's. Notice that 2I came a short time after 1I. Click image to enlarge.
CENTER: A visitor from Oort Cloud has been spotted in March 2022 by Californian astronomers. The Green Comet or C/2022 E3 (ZTF) flew closest to us on 1 Feb 2023, at a safe distance of 0.28 AU. Green light was due to a complex interaction of UV sunlight with C2 molecules it ejected (among others). This comet was initially classified as an asteroid, and may or may not become interstellar after this passage through the inner Solar System.
RIGHT: A large (up to 9 km radius) Oort cloud comet C/2017 K2 PanSTARRS, passing by stellar cluster M10 in 2022 near its 1.797 AU perihelion. On nearly-parabolic inbound orbit (aphelion ~50000 AU), it started outgassing & creating coma early on (beyond the distance of Saturn), probably due to the CO ice sublimation.

We empahasize theory, but confront the theories with observational facts, including some of the newest discoveries. Part of our course deals with small bodies and dust, an important component of circumstellar dust disks, which represent young planetary systems. At the end, we consider the basic astrobiology.

Course and textbook

Planetary system science is developing quickly. Appropriate, all-encompassing, textbooks at the upper undergraduate level are few and far between. Therefore I mostly teach from own notes. Behind the scenes I use my textbook published in 1995, which has no English language edition or an electronic form. Almost everything I want you to know, I put into the lectures+recordings and lecture notes (in PDF form). What you learn in the lectures should partially prepare you for the written problems found in the homeworks (assignment sets 1-4) and the exams. I very strongly encourage your attendance at lectures, taking your own notes, and asking questions during lectures - please feel free to interrupt me, or after lectures. If you don't engage in this way, you may find it difficult to undestand the provided lecture notes.
I also mix in some material from a widely-accessible textbook.

"Fundamental Planetary Science: Physics, Chemistry and Habitability" by Jack J. Lissauer and Imke de Pater (2013, 2019). I will mention where to find the book in the tutorial.
Be careful not to confuse it with the book "Planetary Sciences" (by the same authors), which is a different, graduate-level, version of the book I mention in the section on other books.
You don't have to read the whole book. Several chapters might give you another angle on or another wording of issues than Lectures, but they are not required reading. Only Chapter 15 is obligatory, please read it.

Other books

There are some other books worth reading listed on a subpage. They are not obligatory but some you may find them interesting, and can be good choices for extracurricular reading. See about activity points below.

Marking Scheme:

4 sets of home assignments: 32% (8% each set)
midterm: 21% (10% problems + 11% quiz)
final exam: 44% (22% problems + 22% test)
class/tutorial partic. & activity*: 3%
Max score: 100%

Grading is standard: minimum percentage marks for letter grades (for orientation only, since grades are reported as percentages)
A+ 90%, A 85%, A- 80%, B+ 77%, B 73%, B- 70%, C+ 67%, C 63%, C- 60%, D+ 57%, D 53%, D- 50%, F 49% or less.

*)- the activity points are awarded for participation in lectures and tutorials, and asking questions. Full points will be awarded for coming to office hour and sharing the knowledge gained from reading an optional book, if the level of the book is appropriate, subject concerns planetary systems, and I find that you understood the book. Examples of appropriate books are linked in the previous section. Email me the author and title of a book that is not on the list of recommended books, or show it in person. It will need to be approved (scope, level).

Contact information including emergencies & office hours

Please mention ASTC25 in subject line, or your mail may get lost.
Lecturer: Pawel Artymowicz, email: pawel AT utsc.utoronto.ca, or pawel.artymowicz AT utoronto.ca, 416-3584275 (please text).
TA (marking & email answering): Ritik Kothari (ritik.kothari AT mail.utoronto.ca)

Preferably use mail.utoronto.ca service, avoid sending mail from gmail. UTSC mailer has problems with responding to gmail. Please mention your student number when discussing your personal questions or marks (the temporary results file only lists the last digits of your student number, not your name.) Do not send email or comments to me via Quercus (I rarely check things there, and it's impossible for me to reply.)

Office hours: between lecture and tutorial & immediately after tutorial.

Homework problems

General info

The format and the way of submission of solutions is electronic: take readable snapshots or scans of *neatly* hand-written, numbered pages, indicating your student number. Convert to one .pdf document. (If you hate handwriting, you can typeset your solutions and upload them as .pdf or .doc but then you will have to spend extra time doing the sketches/diagrams which you'd otherwise quickly do by hand.) You submit your term work to Quercus/Assignments before the deadline posted in the syllabus. Your TA will be an authority on this process. Your solutions may be checked for possible plagiarism (i.e., overlap with fellow student's work or with internet pages; if you quote online resources, clearly reference the source).

Please remember to number the pages and sign all of them with your name and last 3 digits of student number, say, "...123". Write legibly; very messy homeworks cannot be graded. Please give enough details IN WORDS of the solution procedure. It's as important as the correct final answer. And don't forget to follow the guidelines on what a decent solution must contain (below) such as checking physical units.

Everything you submit and the comments by the marking TA will be visible on Quercus. It will allow multiple submission of the files before deadline, so if you have corrections to your solution please post an updated file before the deadline (so it's not marked as late). You will be able to see and check a computational/calculational solution against a published one. This will make long explanations by the marker (TA) unnecessary, so don't expect very detailed comments on Quercus. Individual problems will have a nominal point value displayed, and the TA will report your marks relative to these max scores. But the eventual "out of" or maximum score for a given task will be decided by the lecturer, and sometimes slightly re-adjusted toward the end of the course in your favor. Check the preliminary results file further down on this web page. The "out of" line gives the number of points yielding 100% mark for a given task.

What steps are required for full solution?

A fully solved problem may require all of the following steps:
  1. A sketch of the situation
  2. Analytical part - manipulation of symbols to find the required relationships between quantities
  3. Units checks
  4. If units are ok (then & only then) substitute the constants and values, calculate the results
  5. Decide whether results make sense (e.g., is the order of magnitude ok?)
  6. Write up final version legibly and clearly, put student # on the 1st page. Explain in words what you're doing, don't just write equations.
The same applies to written problems in exams. Of course, some problems may not require pts. 1, 3, and/or 4.

Deadlines. Time: the beginning of first lecture (13:00).

The intention is to give you 8-9 days to solve problems really meant to be done in 7 days. But don't put the work away until the last days. This often creates big problems. Plan ahead for a timely submission of solutions. Quercus flags any late submission and tells us exactly when you submitted it. Late by 10 minutes? We will accept it, assuming technical problems. (Start submitting sufficiently early, if your network has problems.)

There are no extensions for assignments. It is both because of the fairness to all those who respect deadlines, and the pedagogic needs (right after the deadline we post and/or discuss solutions in the tutorial.) AccessAbility students will receive an accommodation consisting of 12-13 days to solve assignment.
Either late submission or point transfer will be done at the discretion of the professor only in proven medical or personal or family emergency/bereavement, which you will need to prove in the University-prescribed way [either Absence (Self-)Declaration via ACORN, only 1 week allowed per term, or University Verification of Student Illness/Injury (VOI), which is a doctor's note. Send me the document.]

Likewise, a special treatment will be extended to justified & documented absence at midterm. There are no deferred midterms in ASTC25. Points will be transferred to final exam; you must submit a self-declaration on Acorn and send me a copy, see this page).

Please do not ask for individual extensions because of assignments/exams in other courses - such circumstances are not emergencies, not a sufficient ground for exceptions, and granting them would be unfair to others. Work in other courses should be known and taken by you into account ahead of time. Use the extra 2 days you have to solve any scheduling problems.

🤔   Four problem sets

If there are misprints or anything else unclear about the problem set and/or access to it, please ask immediately and allow up to a day for an answer. It is too late to ask one day before the due date.
Set A1. Due Thu 30 Jan. Formulation Prob. set 1, PDF . Solutions : cf. this PDF .
Set A2. Due Thu 13 Feb. Formulation: In this PDF . Use summary of facts on orbital motion from A1. Solutions: cf. this PDF.
Set A3. Due Thu 13 March. Problem formulation: In this PDF. Solutions of A3: this PDF
Set A4. Due Thu 4 Apr 10pm. Last set: this PDF. Solutions: this PDF

😞   Note on plagiarism, including the use of "AI"

Plagiarism and cheating do happen, sometimes by ignorance. When we notice strange non-sequiturs in your written problem solution, or close similarity of your solution to your fellow student's, or to some web page (wiki, google, "AI" such as chatGPT), it will be up to you to orally convince us that *you* originally wrote and understand what you have submitted. (Plagiarism is to misrepresent as your work something that isn't your own work). Failing that, harsh procedures and/or penalties that UofT mandates will apply. Read more in offical docs. If we find someone cheating with a button camera, transmitting phone in the bag/pocket & earphone during an exam (detectors start from $25 on Amazon), they will not finish & formal incident report will be filed. Not worth it in this or any other course!

Lectures (pdf + animations)

Lecture numbers correspond to the lecture number in syllabus.
L01_02-ASTC25-2025.pdf ,   L03_04-ASTC25-2025.pdf ,   L05_06-ASTC25-2025.pdf ,
     Phobos 1. (mpeg) ,
     Phobos 2. (mpeg),
     Phases & Libration of the Moon in 2012 (youtube),
L07_08-ASTC25-2025.pdf ,   L09_10-ASTC25-2025.pdf ,
     Disk formation. (mpg) ,
     Cluster formation. (avi),
     Hydrodynamic instability in a disk near the black hole. (mpg) ,
     MHD (magnetohydrodynamical) calculation of MRI (magnetorotational instability). (mpg) ,
L11_12-ASTC25-2025.pdf ,   L13_14-ASTC25-2025.pdf ,   L15-ASTC25-2025.pdf ,   L16_18-ASTC25-2025.pdf ,
     Brown dwarf opens a gap in a gas+dust disk, (mp4)
     Dust avalanche simulation. (mp4)
     Irradiation instability, gas disk. (mpg)
     Irradiation instability in gas disk. Modal growth. (mpg)
     Irradiation instability, particle disk, tau=4. (mp4)
     Irradiation instability, particle disk, tau=12. (mp4)
L19_23-ASTC25-2025.pdf ,
     Beta Pictoris planet orbiting (2013-2018). (gif)
     51 Eridani planet orbiting (2014-2018). (gif)
     HR 8799 planets orbiting (2009-2016). (gif)
     Jupiter opens a gap. (r,phi) coordinates, (mp4)
     Jupiter-mass protoplanet migrates. (mp4)
     Migration, type III - outward migration.
     Migration, type III - inward migration.
     Saturn's mass protoplanet - migration type III.
     One of 4 vortices generated by a 5-Earth mass planet.
L24-ASTC25-2025.pdf .

Tutorials

See this page. Tutorials are important for preparation to written parts of exams.

Brief FAQ

Q: What do I need to write an exam?
A: Calculator, pens, knowledge. (Exam booklets and exam's text will be supplied.)

Q: What is the format of the final exam?
A: Exactly the same as midterm, just longer. The level of difficulty is also the same. 2/3 of final are from the post-midterm material, 1/3 from the pre-midterm material.

Q: Are exams open-book?
A: No they are not. Electronic devices except calculator are also prohibited.

Q: Are own notes allowed at exams?
A: YES, own handwritten (not photocopied) notes are allowed: 4 pages at midterm, 8 pages at the final. That's pages, not sheets. You decide if the notes are single-sided or double-sided, and what to write in them. (There is no need to copy tables of planetary data, since all the constants needed for the solution will be provided in the exam.) You retain the midterm notes, you can re-use them during the final.

Q: Until when can I drop the course without academic penalty?
A: Until about 25 March or so, google the UTSC sessional dates listing.

Q: Is my presence at *all* lectures and tutorials required?
A: It isn't enforced or mandatory, but it expected & VERY helpful for you to attend both the lectures and the tutorials. The lectures DO NOT follow literally a single book or 2 books, except for sometimes quoting the assorted fragments of our textbook 1 (book no.1 above). Advantages of participating in meetings are many: (i) the points for participation (see Marking section), (ii) you get information beyond what's in the textbook and posted materials, some of which may be *very* valuable at test/exam. I strongly encourage and expect you to engage and take own notes (I do write some things on the blackboard or whiteboard). Not everything will be recorded. Most of the (exo)planetary system theory is not yet found in any undergraduate textbooks, so hearing it presented in our meetings will be helpful. We will be discussing solutions to home assignments and solving new problems during the tutorials. Tutorials are your ability to use the theory, in the written part of exams, and beyond.

Q: Will there be recordings of lectures made available and can't I just use them instead of coming to in-person meetings?
A: We provide lots of material online but it does not replaced lectures or tutorials. Recordings from earlier years or from AURA (semi-automatic system) will be posted in Media Gallery on Quercus. There are occasional glitches in both, including downtime of microphone because batteries fail, bad visibility of blackboard, and so on. The course is in-person, so you should not primarily rely on recordings but attend all the lectures & ask any questions you have in class or during the break. You will also have the current PDF lecture notes and some tutorials writeups, below. Re-download them every week, since a small part of each file is normally updated or expanded shortly before and sometimes after the lecture.

Q: I have a schedule conflict with another course. Can I skip all the lectures (or all tutorials)?
A: If you have a scheduling conflict, a fair advice would be: preferably drop the other course or, if need be, this course. If you cannot follow this advice, you'll have to rely on recordings, which are not guaranteed to be full and of high quality, especially of the tutorials, which are impossible to record well.

Q: Is this page going to be always visible or should I download things I need from it to my computer?
A: It did happen once that the 'planets' server became unreachable 2 days before the exam. The networking problem was solved in the last minute, putting a lot of stress on those who did not download the preperatory material ahead of time. Set up a directory on your computer and download or refresh lecture notes and other files you may need (syllabus etc.) need every week, e.g. during the lecture.

Midterm exam - general info & preparation

It started 16:05 and ended 17:04 on 27 Feb (in tutorial).

There will be two written problems. They require calculations. Use the blank pages of exam booklet as scratch paper. We won't mark those. Your final solution should be legibly written on lined pages.

You do the Quiz on the supplied exam sheet (please do not list quiz answers in the exam booklet!)
Mark the correctness of the sentence (Y/N) in front of the sentence. If you answer N, please also circle at least one word or number which is incorrect, otherwise your answer will be treated as a guess (no penalty but no credit, either).
Written part requires calculations. If you need scratch paper for that, use the blank pages of the exam booklet. We won't mark those. Your final solution must be found legibly written on lined pages.

Everything that was in the lectures and tutorials (and assignments) up to the reading week can be the subject of midterm exam, so study the notes up to and including L10 (up to SPH simulation of star cluster formation), all posted recordings, and the tutorial notes.

Midterm Quiz will be testing notions and facts discussed in Lectures. The texbook may provide additional clarifications but is not required for the midterm. (This may not be the case in the final exam, chapt. 15 of Lissauer/de Pater book will need to be read.)

Own handwritten notes and calculators will be allowed at midterm (see FAQs above). Nothing else is allowed, no electronic devices during the exam. Quiz usually takes about 20 min. You decide what to do first, quiz or written part. But remember that they carry approximately the same weight, so probably doing Quiz first makes more sense.

A training set of quiz questions is provided below. This version has about 50% of answers provided. Not sure if the scope exatly covers all lectures up to the SPH simulation of star cluster formation in L10 (the required material are all lectures up to this point). PDF.
Next I provide a set of sample written problems . Just like the Quiz, to prepare well for the exam, please solve the unsolved items with or without the lecture notes and texbook in hand. Problems without solutions . And here is the set of the problems with most answers or hints provided, but you should use it after you find your own solutions: problems-with-solutions .

Remember that a fully solved problem (in exam or assignment) may require all 6 points listed earlier in the section on homeworks.

Study the format of midterm in this actual 2024 midterm file. midterm 2024 w/solutions. There may be some overlap with the preparation files above.
In 2024, the midterm problem was about:

Midterm on 27 Feb 2025 (16:00-17:00)

2025 solutions are posted here in this PDF  

Instructions and preparation for the final exam on 21 April (IA2160, 14:00-17:00)

Format of the final exam is the same as midterm.
For the quiz, review the files of lecture notes, your own notes, and/or recordings of lectures. As for the Lissauer+DePater textbook, please only read chapter 15. Read it thoroughly.
Sample quiz questions, many solved, is before the exam in this PDF file. For credit, remember to circle incorrect word(s) in case you choose N as answer. No attempt to cover all the lectures equally is made in this file.

As to the written problems, please also remember to check the preparatory material for the midterm and all the posted homeworks & their solutions. I'm not including those things in the problems below, although I have covered most of the course material in preparation file for the Quiz.

The problems WITHOUT solutions, PDF file . The problems WITH solutions, PDF file .

Final exam 2025

PDF file .

Sample of Ostlie & Carroll

Annotated copy of chapter 2 of Ostlie and Carroll's book can be downloaded from here (pdf 5MB), to help you improve your knowledge of the Kepler problem, Newtonian physics etc.

Your points

preliminary (text file).

Interesting links


To the local home page of Pawel Artymowicz
Last modified: 2025