Astronomy 16 – Astrophysics: Stars, ISM, and Galaxies
Archive of Assignments
Homework assignment 6 [pdf] is due on Friday, November 17 at 5pm. (Note: typo in last problem has been corrected.)
Read the assignment for class 19 [pdf] to prepare for Tuesday's class (refer to the notes posted for class 18 [pdf] too). And also look over these slides of ISM images [pdf] (some of which we looked at in Thursday's class and the rest of which we'll look at next Tuesday).
Read the assignment for class 17 [pdf] to prepare for Tuesday's class.
Work on your imaging labs, preparing to finish them up on Monday night.
Homework assignment 5 [pdf] is due on Monday, November 6 at 5pm.
Read the assignment for class 16 [pdf] to prepare for Thursday's class.
Read the assignment for class 15 [pdf] to prepare for Tuesday's class.
Read these guidelines for the midterm [pdf], which will be Monday at 8pm in SC 187.
Read the assignment for class 14 [pdf] to prepare for Thursday's class.
Read the assignment for class 13 [pdf] to prepare for Tuesday's class.
For our lab meeting on Monday night ‐ work on your data, answer your question, or work on posing a question and planning your observations if you haven't done those things already.
For class on Tuesday, review the second half of Ch. 14 – luminosity class and the HR diagram.
The lab information and the HR diagram and spectral type and luminosity class slides from last week are posted below. You'll be using them for your work this coming week.
For Thursday's class, please take a look at these slides [pdf], which contain images demonstrating the spectral type sequence, luminosity class, and the HR diagram. And read the assignment for class 12 [pdf].
Homework assignment 4 [pdf] is due on Friday, October 13 at 9pm.
Read the assignment for class 11 [pdf] to prepare for Tuesday's class.
Reposting from last week: Our next lab will be done in groups, and will involve students choosing an interesting, extended object to observe and produce an image of, with the goal of answering a question that they've posed. Take a look at the information about lab 3 [pdf] and then the list of objects you might observe [pdf]. Students' next move is to email Prof. Cohen to let him know what object you'd like to observe and to arrange to plan and make some observations of that object. This can be done anytime, with observations made on any clear night before fall break. New: You can/should do a little looking and background researching at Astronomy Picture of the Day and on the Messier Monday blog. You can use this tool to see when a given object will be up at night in Swarthmore. And you can monitor the weather models as you think about when you can make your observations. Finally, enter your name on this master-list of objects and student groups.
Look over the slides from class 10 [pdf] showing spectra of binary stars.
Look over the slides from class 10 [pdf] showing spectra of binary stars.
Read the assignment for class 10 [pdf] to prepare for Thursday's class.
Our next lab will be done in groups, and will involve students choosing an interesting, extended object to observe and produce an image of, with the goal of answering a question that they've posed. Take a look at the information about lab 3 [pdf] and then the list of objects you might observe [pdf]. Students' next move is to email Prof. Cohen to let him know what object you'd like to observe and to arrange to plan and make some observations of that object. This can be done anytime, with observations made on any clear night before fall break.
Take a look at my solution for the in-class absorption line problem from Thursday [pdf], but only after you've finished it yourself. Then check your answers against mine.
Read the assignment for class 9 [pdf] to prepare for Tuesday's class.
We'll start class on Thursday morning with a small problem that will help you solidify your understanding of spectral absorption line strength and how it relates to important physical quantities. If you have time, take a look at that problem [pdf] before coming to class.
Homework assignment 3 [pdf] is due on Wednesday, October 4 at 5pm. But there are two small computational problems that have to be submitted via email earlier than that.
You can (should!) take a look at my solutions for the two pre-class problems from Tuesday [pdf].
Read the assignment for class 8 [pdf] to prepare for Thursday's class.
Read the assignment for class 7 [pdf] to prepare for Tuesday's class.
Read the assignment for class 6 [pdf] to prepare for Thursday's class.
Homework assignment 2 [pdf] is due on Friday at 5pm.
Read the assignment for class 5 [pdf] to prepare for Tuesday's class. New: you can look over the slides from class 5 [pdf]. Note that we didn't get to the very last one. It's an extreme ultraviolet image of the Sun, taken through a filter centered at about 170 Angstroms – so about 40 times shorter wavelength than visible light, and the plasma emitting this light is about 40 times hotter than the surface of the Sun (so, about a quarter of a million degrees). The Sun looks so different at this wavelength - we don't see its surface, but rather hot, magnetically confined, and flaring plasma above its surface. Just an example of how different wavelengths of light can give us very different views of astronomical objects. Also: here are the questions handed out in class [pdf]. You did the first one. But bring the worksheet to class on Thursday, when we'll do the other two.
Information about our second lab is available: Read the manual [pdf] and get started installing the AIJ software and downloading the data before coming to lab. Read the manual carefully and note that there is some additional reading assigned within the manual. You will also need these two AIJ tutorials to reduce the data [pdf] and to perform the image analysis [pdf].
Homework assignment 1 [pdf] is now posted. It's due on Wednesday at 5pm.
When you have a chance, read over this Word document containing some follow-up notes about our first lab.
Read the assignment for class 2 [pdf]. Note that you have to solve the last two problems of the four pages I handed out in class on Tuesday. Here are scans of the readings from the textbook: pp. 29-34, pp. 50-53 and 74-75, p. 73, pp. 61-62, and pp. 78-80 [all pdfs]. And here is the handout/problem we did in class [pdf] (drawing a circular orbit superimposed on a highly eccentric orbit) along with my solution [pdf].
We'll discuss on Thursday in class the actual methods and chronology of the human discovery of the scale of the Solar System. As mentioned in Tuesday's class, the ancient Greeks measured the size of the Moon relative to the Earth by looking at the shadow of the Earth on the Moon during lunar eclipses and noting the relative radii of curvature, as shown in the single image of a lunar eclipse and more easily seen in a time-lapse:
You can see from these images that the Earth is between three and four times the size (radius) of the Moon. Also note that as Venus orbits the Sun, it has visible (with a telescope) phases and that it never strays too far from the Sun.
To prepare for our first class, on Tuesday, read assignment 1 [pdf] and think about the points I raise in it. There are three very short things for you to read in that assignment: Bennet pp. 90-92, 98 [pdf], first approximate derivation of the expression for centripetal acceleration, second derivation.
Read the information about lab 1: imaging at the Peter van de Kamp Observatory [pdf]. Reading related to the lab: Ryden and Peterson, first few pages of Ch. 1 [pdf] and A short introduction to astronomical image processing.
There is a short (two problems) homework assignment [pdf] due on Monday by 5 pm. That's the day before our first class meeting. To help you think about the material in this assignment, watch this short (34 second) video.
Look over these images and movies of the recent solar eclipse and think about this: When we say the Moon and Sun appear to be the same size, what is it, exactly, that's the same about their sizes? Certainly not their diameters or radii in kilometers.
credit: Richard Sparkman
An assignment to help you prepare for the first class meeting will be posted here about a week before classes start.
Do what you can to see the solar eclipse on August 21. It will be partial in Philadelphia but the path of totality stretches from Oregon to South Carolina.
Return to the main class page.
This page is maintained by David Cohen
dcohen1 -at- swarthmore.edu
Last modified: November 20, 2017