Astronomy 16: Modern Astrophysics
Archive of Assignments
Look over the images I showed in class 26 on Thursday [pdf].
Read the assignment for class 26 [pdf] -- there's some great material in there: read my assignment carefully, as it tells you what to focus on.
Look over the images I showed in class 25 on Tuesday night [pdf].
Homework 9 [pdf] will not be graded, but students are responsible for knowing how to solve the problems on it. Solutions will be sent out by Sunday, December 4.
Read the assignment for class 25 [pdf] which includes reading two sections of Ch. 19 (and just skimming the middle four sections). Note that the class will meet at 8pm on Tuesday night in the seminar room.
Please re-read the last two pages of the assignment for class 23 [pdf] (last Tuesday). We'll start class on Tuesday morning talking about the Chandrasekhar limit for white dwarf masses. And then move on (briefly) to neutron stars and black holes, and begin our (again, brief) study of the Milky Way Galaxy. To prepare for that, read the assignment for class 24 [pdf] (which includes neutron star/black hole material as well as Milky Way material).
Please read this assignment for class 23 [pdf] on Tuesday. We'll be finishing up stellar evolution and moving on to white dwarfs and degeneracy pressure.
You should have a look at these guidelines for the second midterm [pdf].
Homework 8 [pdf] is due by 5pm on Monday the 21st.
Look at these three images related to star formation [pdf] before coming to class on Thursday.
Here is the assignment for class 22 [pdf] on Thursday.
Please read this assignment for class 21 [pdf] on Tuesday. We'll be finishing up the interstellar medium and moving on to star formation. You will want to refer back to the notes/handout I gave you in class on Thursday [pdf].
Also look over the slides I showed in class last Thursday (about the interstellar medium) [pdf].
The assignment for class 20 [pdf] on Thursday is available. Please take a look at it and finish reading Ch. 16 prior to coming to class on Thursday.
Homework 7 [pdf] (note: mildly updated 11/11) is due by 5pm on Monday.
Read the assignment for class 19 [pdf] on Tuesday. It's mostly reviewing the material we haven't yet discussed from Ch. 15, but only a little new stuff from Ch. 16.
Read the assignment for class 18 [pdf] on Thursday. Note that there isn't much more reading from the textbook for Thursday's class, but I've put more detailed than usual information/notes together. Please read it carefully before coming to class.
Read the manual for Lab 2, part 2 [pdf] prior to coming to lab on Tuesday night at 8pm in SC 187. You can get started with the photometry (and even lab write-up) ahead of time if you want. But it's fine to start working on Tuesday night in lab. However, you'll want to read the manual ahead of time. And bring your computer with your reduced data from last week on it.
Read this assignment for class 17 [pdf] on Tuesday. We'll start going down below the surfaces of stars, into their interiors.
Homework 6 [pdf] is due in class on Tuesday.
Read over the images I handed out in class 16 [pdf]. Come to class on Tuesday with any lingering questions about spectral types, luminosity classes, and the HR diagram. And also, read over the handout on Fig. 5.13 and the basis for spectral types [pdf]. Go back and read the text in Ch. 5 that describes what's going on in this figure and see if you can answer the questions on the handout. The idea is that this figure explains the trends of hydrogen Balmer-alpha absorption line strength with temperature, based on the combined application of the Saha and Boltzmann equations. We'll go over the handout in class next Tuesday.
Read this assignment for class 16 [pdf] on Thursday. Note that it consists basically just of reviewing the material you should have already read from Ch. 14.
Read the manual for Lab 2, part 1 [pdf] prior to coming to lab on Tuesday night at 8pm in SC 187. You should download the WASP-11 data before coming, and unpack the zip archive. Beyond that, you can do (and, I'm sure, complete) the data reduction in lab on Tuesday night or you can do it on your own or you can start doing it and then come to lab to get questions answered and just finish up. I suspect that most of you will be able to complete the work in an hour or less, and probably faster if you do it in lab with me so I can help you if you run into problems. If you choose to just do the lab on your own and not come to the lab meeting to get help on Tuesday night, please note that you'll still have to email me a few things by midnight on Tuesday in order to get credit for doing this part of the lab.
Once again, you'll probably want to do this lab and work with these data on your own computer to give yourself work flexibility. But, I'm very happy to have you use the desktop computers in 187 if you prefer. Please let me know ahead of time if the latter is the case.
Read this assignment for class 15 [pdf] on Tuesday.
Read this assignment for class 14 [pdf] on Thursday.
Homework 5 [pdf] is due by 5pm on Friday. Update (10/18): Now due by noon on Monday the 24th.
Read this assignment for class 13 [pdf] on the Tuesday after break. Note that includes a very small problem that you have to hand in by 6pm on Monday.
A lab assignment – working with exoplanet data (that's already been taken) will be posted here shortly.
Please review the handouts I gave you at the end of Thursday's class. Here's an explanation of each (and note: I've added some stuff to the handout with the stellar spectra – I've added a second spectrum): spectrum of a binary star, and a different binary star where you only see the spectrum of one star, several exoplanet transits (same figure from Tuesday (below), but this time, focus on the light curve as a diagnostic of planet size and maybe also, its path across the face of the star), and a paper on an exoplanet discovery made here with our telescope [pdf] – I gave out pages 2 and 3, which show the radial velocity curve of the host star (used to weigh the planet – using eq. 12.21 from the texbook), and transit light curves (including one labelled PvdKO taken at Swarthmore) which are used to measure the size of the planet. The link here is to the whole paper. Please study those two figures (Figs. 1 and 2). You might also read the abstract on page 1, which summarizes the results (though it's full of jargon – some of which you'll learn over the rest of the semester). Also – here is the radio (ALMA) image of the star with the protoplanetary disk.
You can (and should) review the images of the Sun I showed in class on Tuesday:
solar image showing limb darkening
exoplanet transits show effects of limb-darkening
rotationally broadened spectral lines don't look like semi-circles
corona and chromosphere during a solar eclipse
video of plasma in strong magnetic field
a magnetic loop in the far-ultraviolet
full Sun in the far-UV during a flare
real-time movies of the Sun at different wavelengths
Sun's magnetic field – note both small- and large-scale
Read this assignment for class 12 [pdf].
Homework 4 [pdf] is due at the beginning of class on Thursday.
Read this assignment for class 11 [pdf]. Note that most of Tuesday's class will be spent on the material from Ch. 7 on the Sun, as well as looking over your Whirlpool Galaxy images and especially, the steps along the way to reducing your data – something you'll be doing for the next lab, where you will be working with exoplanet transit data. And we can also spend some of Tuesday's class answering questions about the midterm and about the solid angle and other concepts from last Thursday's class.
Read this assignment for class 10 [pdf].
Your Whirlpool Galaxy images with images of each key step along the way, as described in the lab manual, are due on Monday by midnight. See the Archive of old assignments page linked at the bottom of this section for the original announcement and information with useful links. Also, take a look at the discussion forum I just set up on Moodle. I've posted some questions and answers about AIJ and the lab there. Please post any additional questions you have there (as well as emailing me). And I'll post my answers so everyone can see them.
Tuesday's class will start with a wrap-up of loose ends. Some of this might be relevant for your midterm studying! Then we'll begin our next section, on the Sun. Read this assignment for class 9 [pdf]. It's relatively short. The bulk of the material in Ch. 7 will be discussed on Thursday.
You can read guidelines for the first midterm [pdf].
For our lab meeting tonight, we will be learning how to reduce data from the telescope and how to make a color composite image. In lab, we will practice on a set of images of the Dumbbell Nebula – there will be nothing to write up from that. Then, outside of lab, students will solidify their knowledge by making a second image, of the Whirlpool Galaxy, this time putting together a brief write-up that will be primarily a notebook of images made at each step of the data reduction process. That write-up is due by midnight on Monday. Here is the lab manual, the data analysis and reduction guide, the Dumbbell data and the Whirlpool data. And the software we'll be using is AstroImageJ, which students should install on their computers.
Thursday's class will be for wrapping up the radiation and matter material. Read this short assignment for class 8, on Thursday [pdf].
Please look over the reading assignment for class 7, on Tuesday [pdf].
Homework 3 [pdf] is due at the beginning of class on Thursday.
We looked at (and will come back to in more detail) a solar spectrum in class on Tuesday. And we'll look at various spectra in the lab again. We will continue talking about atomic processes on Thursday. After we discuss recombination, I'll ask you to work on this problem [pdf] with your classmates. Have a look at it ahead of time, and start thinking about it and bring it to class with you (nothing to hand in, though). New topics we'll discuss on Thursday include line broadening mechanisms and the Doppler shift. Look at the reading assignment for Thursday's class [pdf] in order to prepare. It includes about six pages of reading, with a few paragraphs of my commentary. For your convenience: the Wikipedia page on the Doppler effect.
Please look over the reading assignment for Tuesday's class [pdf] and do the reading (and thinking!). Come to class on Tuesday with questions.
Following up on Thursday's class, please look over the following: current images of the Sun (you can still see "our" sunspots, but they've rotated further over), my solution to the binary star problem [pdf], a short proof of Kepler's third law for circular orbits, showing where the M+m comes from [pdf], and the current state of my sheet of equations and constants [pdf]. I should probably have more conversion factors on there, but you can compare your sheet to mine. Please also spend some more time exploring the orbit simulator. Explore some of the pre-sets (pull-down menu at the top right). And try to make a circular orbit. Note that you'll need to use the simulator for one of the homework problems. I've just made an elliptical orbit for two objects with similar masses and take a screenshot. Take a look and make sure you know how the semi-major axes of each orbit is defined and how the total semi-major axis, a = a1 + a2, while definable using the image doesn't appear as a single entity when you look at the orbits.
Homework 2 [pdf] is due at the beginning of class on Tuesday.
Our first lab meeting is Wednesday night. You should review the material in the first half of Ch. 6, but otherwise there is no pre-lab assignment and there will be no lab write-up. The goal of this lab is simply to teach you how to use the telescope and camera, and to explore the properties of the images our telescopes produce. We'll see how noise affects our images, evaluate the atmospheric seeing, and explore the effects of changing the exposure time and using different filters.
Please look over the reading assignment for class 4 [pdf]. There is no new reading, just reviewing. And one problem to solve.
Please look over the reading assignment for class 3 [pdf], which really is simply instructions on reviewing the gravity and orbits material (see the Archive of old assignments link below for the class 2 assignment and related resources) and also reading about observational astronomy (telescope, detectors) in preparation for our lab meeting and beginning to work with data from the telescope. You can also review the images I showed on Thursday in class: annular solar eclipse and Venus transiting the Sun. You might also (for comfort with the small angle approximation) look over this information about Taylor series and for another way the Greek's estimated the size the Moon, look at this time lapse of a lunar eclipse, making it clear that the relative sizes of the Earth and Moon can be discerned from the observed curvature of the Earth's shadow as seen during an eclipse.
I will soon post information here about our first lab, though the only preparation you'll have to do is the textbook reading in the class 3 assignment.
Homework 1 [pdf] is due at the beginning of class on Tuesday.
Please look over the reading assignment for class 2 [pdf], on Thursday. There is a small amount of reading in the textbook (on Kepler's laws), plus I ask you to look over these two short derivations of the expression for centripetal acceleration: [approximate but simple and more detailed and almost rigorous] and to make an orbit using the gravity simulator (which is permanently linked on the right side of this page). Also, please bring the in-class question from last time about the Moon's radius to class on Thursday and bring your print out of the finding-angles-with-your-hand guide, too. And come to class with questions.
Today in our first class, students worked together to apply the distance-size-angle relationship to determine the size of the Moon [pdf]. And we did a little (indoor) practice measuring angles with our hands. We also looked at this Hubble Space Telescope image of the Carina Nebula and Star Formation Region and this image of a partial solar eclipse (with the Space Station). Note that these Astronomy Picture of the Day images have informative descriptions.
The reading assignment for the first class [pdf] includes two problems that you must hand in by 6pm on Monday. Note that the reading is available on our class Moodle page (though just for this week; the book is available in the book store and at Cornell library).
Return to the main class page.
This page is maintained by David
cohen -at- astro -dot- swarthmore -dot- edu
Last modified: December 6, 2016