ASTR 510 Homework


Thinking is the most important part of this course, and our methodology is ask questions, think about the answers, investigate the topic and answer the questions, then think about what we've learned. So for all reading assignments, write down a few questions that come to mind. If you are not generating questions, you are probably are not thinking enough about what you are reading. Thinking and generating questions, then later going back and answering those questions, are key parts of how we will learn in this course.

Note: For various pedagogical reasons, all homework must be typed. And of course, it should be written using proper English at the advanced college-level (e.g. no colloquial expresssions, always include references if appropriate, and use precise terminology).

ERRATUM: For our Lecture 23 (corresponding to the old 2021 Lecture 24 notes on Canvas), there is a typo in the formula for the equilibrium temperature Teq. The exponent of the day-night correction factor "f" should be 1/4, not 1/2. Here is the correct version:
Corrected typo in lecture notes #23 for Teq

This error no doubt comes from the 1/2 factor that belongs in the (R*/2a) term but was split out incorrectly. I blindly used the expression given by some of the world's experts on exoplanet atmospheres, Burrows & Orton (in the excellent book "Exoplanets" edited by Sara Seager):
Typo in the Burrows & Orton chapter in Exoplanets by S. Seager
Typo in the above formula: f should be to the 1/4 power.
[Note: The Teq formula in the old Lecture 25 pdf file on Canvas is correct; it is old Lecture 24 that has the error.] My apologies for the error. Please correct your notes.


ERRATUM: For our Lecture 21 (corresponding to the old 2021 Lecture 23 notes on Canvas), there were a pair of typos in the exponents. Here is the correction:
Erratum for old Lecture 23 notes with corrections in place

May 3:
- Read Haswell Chapter 7
- "Lightly" Read Perryman Chapter 10.0-10.2; 10.10
- "Lightly" Read Perryman Chapter 11.0-11.2; 11.4-11.41; 11.5, 11.6, 11.7.
* Study for Final Exam on Monday May 10th, 1:00-3:00 pm

April 17: Homework #14
* MLO remote observing from PA-215 on on Thur, or Fri, or Sat nights, from 7pm-midnight
- Review CCD Calibration notes.
- Install AstroImage J (AIJ).
- Read / review the AIJ Flash Guide and User Guide.
- Study for Exam #2 on Monday April 24.
Journal Reading Homework:
- - Read the paper on the discovery of ellipsoidal variations of HAT-P-7 and the associated notes.

Apr 10: Homework #13
- Continue refining your presentation for Wednesday April 12. Send me your title.
- Read Haswell's Chapter 6.
Written Homework #13: (due Monday April 17)
1. Do Exercise 3.4 (page 102) in Haswell's book -and- also plot the three limb darkening laws. In other words, plot the relative intensity I/I0 vs. mu. As always, comment on the results.
2. Show that a planet's surface gravity "g" can be expressed in terms of observables from RV and transit data, and do NOT depend on knowing the mass or radius of the host star (i.e., derive equation 4.49 in Haswell's book).

Apr 3: Homework #12
* Exam #2 postponed until Monday April 24 *
 - Continue working on your class presentation (due April 12).
- Review the class notes on CCD data calibration.
- In Haswell's book, read Chapter 4 and the rest of Chapter 5 (you already read Sec 5.3). (Chapter 5 is the more important of the two chapters; you can "lightly" read Chapter 4).
- "Lightly" read Chapter 7 in Perryman's book. In particular, focus on sections 7.0-7.41 and 7.9-7.10
- [Highly recommended, but not required reading]: The excellent and thorough chapter by Josh Winn called "Transits and Occultations" in the "Exoplanet" book edited by Sara Seager (Univ. Arizona Press).]

Mar 20: Homework 11
- Write up your presentation topic and submit this as written homework assignment #10, due WEDNESDAY March 22.
* Exam #2 postponed until ... *
 - Read Chapter 3 in Haswell's book.
- Continue/finish reading Chapter 6 in Perryman's book (from the start now).
- Continue working on your class presentation (due April 12).
- Review the class notes on CCD data calibration and differential aperture photometry.
- Read the AstroImageJ (AIJ) "Flash Guide" and start the process of getting AIJ installed on a computer that you can use to calibrate and fit data.
Written Homework #11: (due Wed April 5th)
1a. Determine which transiting exoplanets can be observed from MLO on April 20-22 (civil nights Thurs, Fri, Sat). From your list of targets, find those for which (i) transit depth is at least 1 percent; (ii) mid-transit occurs in the early part of the evening, ideally 8:00-10:00 pm, but slightly outside this range is okay.
1b. Choose one target you prefer to observe, and explain why.
To do this assignment, it is necessary to use an ephemeris tool. Two that I can recommend are (i) "skycalc" by John Thorstensen and its more modern image/GUI-driven Java version called "JSkyCalc"; and (ii) the NExSci Exoplanet Archive website. There are probably many other similar tools available.

Mar 5: Homework 10
- Study for Exam #1 on Wed March 15.
- Work on your Presentation topic, due Monday, March 20th. A title and half-page description of the topic is sufficient. Include at least 3 references for now (many more needed later). Explain what the topic is about, why it is important (the motivation), and what you will cover in your 5-min presentation on Wed April 12th. See the "Presentation" section of the syllabus on page 2 for more info.
Journal Reading Homework: The Radial Velocity Method Part 3
- Hubble Space Telescope Time-Series Photometry of the Transiting Planet HD 209458 by Tim Brown, Dave Charbonneau, Ron Gilliland, Bob Noyes, and Adam Burrows (2001 ApJ 552, 699). [This is the famous paper that kick-started the field of high-precision transit science. In my opinion, this is the second most important exoplanet paper ever published, after the 51 Peg paper by Mayor and Queloz.]
- System Parameters of the Transiting Extrasolar planet HD 209458b by Rob Wittenmyer et al. (2005). [Rob was an SDSU grad student and most of this work was in his MS Thesis.]

Mar 1: Homework #9
- In Haswell's book, read Chapter 4 and 5, with emphasis in Ch 5.3 (the Rossiter effect). You can start with Ch 5.3, then go back and read sequentially from the start of Ch 4.
- In Perryman's book, read Chapter 6.18
Journal Reading Homework: The Rossiter Effect:
- "The Rossiter-McLaughlin effect for exoplanets" by Josh Winn
- "Planets in Spin-Orbit Misalignments and the Search for Stellar Companions" by Brett Addison, et al.
Note: I suggest reading Ch 5.3 in Haswell's book (and possibly Ch 6.18 in Perryman) before reading the above papers.
- Begin studying for Exam 1. The focus will be on the material covered in class, Haswell's Ch 1, 2, 4, 5.3, Perryman's Ch 1, 2, 6.18, the papers assigned for homework, and the homework exercises.

Feb 22: Homework #8
Written Homework #8, due Wed March 1.
Use the Systemic Console tool to make RV fits to 51 Peg and also HD 17156 (use the data on the Systemic Console pull-down menu). Turn in the Systemic Console figures and/or screencaptures. Comment on your results.


Feb 20: Homework #7
- In Perryman's book, review Chapters 1 and 2.
Journal Reading Homework: The Radial Velocity Method Part 2
- "Doppler spectroscopy as a path to the detection of Earth-like planets" by Mayor, Lovis & Santos (2014 Nature Review article)
- "On the Determination of Transiting Planet Properties from Light and Radial Velocity Curves" by John Southworth (2017 PASP)
Use Gregg Laughlin's Systemic Console tool to play with and fit radial velocity data. It used to be hosted on Laughlin's fascinating oklo blog but that link is gone (and the blog is less and less about planets in the past few years - but the archive is magnificent). So you can get to Systemic from Stephano M. who maintains (or used to maintain) a version of Systemic 2 and Systemic Live.

Feb 13: Homework #6
Reading homework:
- In Perryman's book, continue reading about the RV method (Chapter 2).
Journal Reading: The Radial Velocity Method Part 1
- Read the famous 51 Peg discovery paper by Mayor & Queloz (1995). This is the paper that kickstarted the modern field of exoplanet astronomy, and helped earned the authors the Nobel Prize.
Written Homework #6, due Wednesday Feb 22:
1. Take the white noise and red noise data sets that your created for Homework #5 Part 3 and cut them into pieces to give you the first quarter, the first half, and the whole thing (no cut). Compute the mean and standard deviation (or rms) for the three parts. What do you notice for the white versus the red noise? Comment on the results.
2. Use the NExScI Exoplanet Archive periodogram tool to make periodograms and phase-folded plot of the four fake data sets that you created for Written Homework #5 part 3. Turn in the NExSci figures and/or screen captures. Comment on the results.
3. Repeat the above, but use xmgrace (called "qtgrace" under Windows) or some other software tool/package to make power spectra (not periodograms). Comment on the results.
4. Explore - play - learn - have fun!. Create new data sets and see what their power spectra look like. Develop some intuition. Part 4 will not be graded, and you do not need to turn anything in. But arguably this is the most important part of the homework. If you do submit an answer I will read and comment on it, but it won't affect your grade.

Feb 6: Homework #5
- Explore the NASA Exoplanet Archive. See what data sets and (especially) what tools are available.
- Journal Reading: Evryscope:
"Evryscope Science: Exploring the Potential of All-Sky Gigapixel-Scale Telescopes" (Law et al. 2015 PASP 127, 234)
See also the Evryscope Poster paper by Nick Law, et al., presented at the Keele Transiting Exoplanets conference (2017 July 17-21).
- Written Homework #5, due Wednesday Feb 15:
1. Haswell Exercise 1.4, page 33, Part (c) only. Show all work.
2. What is the amplitude of the Sun's RV reflex motion due to the Earth?
3. Write some code to generate artificial light curves that (separately) exhibit these three phenomena: (a) sinusoidal (b) white noise (c) red noise. Then create a light curve with (d) all three of these features combined, with roughly the same amount of RMS power. Describe how you generated the time series (but I don't want to see any code) and turn in the figures. Be sure to label all axes and have smart-looking plots like you would see in a journal (e.g. don't have a ton of wasted white space on the figure). Choose sensible units.
Comment on your results.

Feb 1: Homework #4
Reading Homework:
- In Perryman's book, continue reading Chapter 2.
Journal Reading: M-star Planet Searches:
- "Design Considerations for a Ground-Based Transit Search for Habitable Planets Orbiting M Dwarfs", Nutzman & Charbonneau 2008 PASP 120, 317
- "A super-Earth transiting a nearby low-mass star" Charbonneau, et al. Nature, 462, Issue 7275, pp. 891-894 (2009)

Written Homework #4, due Wednesday Feb 8:
1. What are the advantages are of searching for planets around M-stars? What are the disadvantages?
2. What does the term "astrophysical false positive" mean in the context of exoplanet searches?

As always, comment on your answers/results.

* Note: Next week's assignment will require some very simple programming to generate artificial data sets (sine waves, etc., and compute their RMS power). If you are not (yet) comfortable with programming, please see me for some help well before this assignment is due..

Jan 30: Homework #3
* Be sure you are comfortable plotting things. I recommend xmgrace if you don't already know how to quickly make quality figures. (NB: xmgrace is called "qtgrace" under the Windows OS and some Mac OS versions.)
Reading Homework:
- In Perryman's book, start reading Chapter 2.
Journal Homework: Ground-based Planet Searches Part 2:
- "The WASP Project and the SuperWASP Cameras", Pollacco, D. et al. 2006 PASP, 118, 1407
- "The Kilodegree Extremely Little Telescope (KELT): A Small Robotic Telescope for Large-Area Synoptic Surveys", Pepper, J. et al. 2007 PASP 119, 923

Jan 23: Homework #2
Thinking Homework:
(I will not be collecting or grading this assignment.)
Suppose you are working on your mission to find exoplanets, and you have decided to embark upon a wide-field transit survey. You have big pixels on the sky. Why would you want to purposely degrade the image quality of the seeing? Despite worse crowding, and more sky noise, how/why would a bigger PSF actually help? Try answering this question without looking up any papers - just think about what's going on. It is very important that you attempt to answer this before reading the article by Gaspar Bakos about the HATnet. Then, after you have read the paper, go back and update your answer. If you want to change your thoughts, do so by appending a correction. It is important that you do not delete anything in your original answer. Don't delete or cross out your original answer, simply add more to it.

Written Homework #2, due Wed Feb 1:
Make a list of the on-sky pixel size (i.e. arcsec/pix) for the various transit-search programs (HAT, WASP/SuperWASP, KELT, MEarth, Kepler, TESS, etc.). Also, find (or calculate) the pixel scale for the MLO 40-inch telescope. In addition, it would be good to pick other telescopes, not designed for transit searches and see what the pixel scale is for those (e.g. MLO's Evryscope, HST, JWST, etc.). Then, comment on what you find.

Reading Homework:
- In Haswell's book read Chapter 2.
- In Perryman's book read Chapter 6.1-6.5 (pages 153-171)
Journal Reading: Ground-based Planet Searches Part 1
- "Wide Field Millimagnitude Photometry with the HAT: A Tool for Extrasolar Planet Detection", Bakos et al., 2004 PASP 116, 266

Jan 18: Homework #1
Reading Homework:
- Read the syllabus carefully, read the class policies on the class website.
- Explore some of the links on the class website.
- In Haswell's book, start reading Chapter 1
- In Perryman's book, begin reading Chapter 1
Written Homework #1, due Wed Jan 25:
Although I wont collect this homework, please do write down your thoughts.
1. Generate a few questions from your reading of Chapter 1 in each book. We will discuss/answer some of these questions in class.
2. Suppose you are in charge of an observatory and want to find planets via the transit method. What things do you need to consider?




Homework Philosophy & Grading Policy:
 The homework assignments (15% of the course grade) are designed to be relatively easy and broad in scope. They are really a warm-up to get you thinking. Consequently,

  • 1) The goal is not to get the answer. The goal is for you to understand at a fundamental level what is going on. Think: What does the answer mean or imply? What are the consequences? Even if you are not asked to do so, you should always comment on the significance & implications of your answer.

  • 2) Always check your work to make sure it makes sense.
    There are different levels of being incorrect, from slight typos to "not even wrong". There will not be much leniency for errors that make no sense, like if you estimated the orbital period of a planet to be 3 Gyrs, or the mass of a planet to be a million solar masses, etc.

  • 3) Try to do the homework on your own. You can check your answers with your classmates when you're done, but resist working in teams unless you are really stuck. A homework assignment that is nearly identical to another student's may receive no credit.

  • 4) A research astronomer doesn't have someone checking their results, so they have to be confident they have done things 100% correctly. (Well, sometimes a referee of a paper will carefully checks things but they won't check everything.) Just a few errors will erode away the confidence of your colleagues to the point that they can't trust any of your research. Then your career grinds to a halt. Get out of the habit of answering questions as if they were homework questions and into the habit of solving things as if they were research problems. Do your homework such that you are completely confident of your answers/solutions. If you are unsure of anything, then seek help. In theory, I should not have to collect and grade the homework. Rather, we just discuss the topics that folks had difficulty with.

    Each homework is worth 50 points.

    Late Homework Policy:
    Late homework will incur a penalty as follows:
    - 4 points deducted for 1 day late; 1 point deducted each day thereafter.
    The maximum penalty is 10 points (after 1 week). In other words, there is a floor beyond which no additional loss of points will occur. Even if you are 3 weeks late in doing the assignment, it is much better than not doing it at all. The only exception is if the answer to the homework question is discussed in class, in which case that problem is no longer valid for late credit; late homework earns zero credit for this problem.

    If a student is observing the night before a homework is due, the student can take 1 extra day to hand in the homework without penalty, **with permission in advance.**

    If a student is defending their thesis (dissertation or paper) within +/- 2 days a homework, paper, or presentation is due, the student can get a few extra days of time without penalty, **but only with permission well in advanced.**