The Milky Way

Spring Quarter 2015

Instructor: Mel Ulmer

Office: Dearborn Observatory #3 Phone: 491-5633


Office Hours: by appointment, usually open most of (but not all)  9-5 M-F

TA  Pat Stollenwerk

Office: FB 36 Tech


Office Hours:

Tuesday   11:00 a.m.-12:00 noon

Thursday 11:00 a.m.-12:00 noon


Review sessions will be held in Tech (Map of 3rd floor of Tech) M345 (go to the link and type in M345 in the Tech room finder search box)

8:00-9:30 April 17,  May  7 and May 31

Observing at Dearborn

All observing sessions are on Tuesday nights 9:00 p.m.-10:00 p.m. starting the week of April 6.  Last session June 2

Lectures: MWF at 11:00-11:50 A.M.  Annenberg G15

Textbook: Astronomy Today, Stars and Galaxies (8th edition; ISBN-10:0321009720| ISBN-13: 9780321009725 (pbk.: v.2) (Chaisson & McMillan)

3 Exams : Fridays  April 17,  and  May 8,  Plus Monday June 1  (50 min) in Annenberg G15

Optional Paper Due :  Friday May  29 NO E-Mail deliveries allowed, 

No Final Exam:  (3 “Mid terms” and quizzes instead)

The X and Y notations: absence from final examinations and other incomplete work. Students are expected to complete all work in each of their courses by the appropriate deadline. They are not granted permission to make up a final examination or complete other assigned course work after the end of a quarter except in circumstances clearly beyond their control. Instructors may assign an incomplete (Y) or administer a makeup final examination only with prior permission from the Office of Undergraduate Studies and Advising. More information on the policy and process for incompletes is available in the WCAS Adviser Handbook at - 5


We'll have four, 5 minute quizzes on Fridays.  See below for the dates. You can replace one quiz with a paper.  If your paper does not receive a grade higher than you lowest quiz grade, I’ll keep the quiz grade.

The Paper

The paper is no more than one page (12 pt,  1 inch margins,  single spaced) , and  it is to be a critical analysis of an astronomy article from any magazine or newspaper  in the past 1 year.  By critical analysis, I mean did the article convince you the discovery was both interesting and valid.  On the first point, I don’t mean: “Gosh, I  found it so fascinating to learn that there is really and truly a black hole in the center of our galaxy. “  Rather,  I mean is how does the discovery fits into a broader context? e.g., the discovery of a black hole in the center of our galaxy gives proof both that Einstein’s Theory of General relativity is valid and that this gives us insights (OK no direct knowledge of) that perhaps galaxies are all formed about large (a million times the mass of the Sun of more) black holes  On the second point, somebody will say they have proved there is a black hole in the center of our galaxy.  What proof do they offer?  And, why or why not do you find the presented evidence compelling (or not)?  I recommend the NY Times Science Times,  but Astronomy Magazine and  Sky and Telescope will work as well.   Scientific American,  Nature , or Science Magazine are not for the faint at heart.  You must submit a copy of the article along with you paper.


Grading Policy

The course grade will be on 3 "mid-term exam" (25%, 25%, and 30%; 80% total)  and quizzes (20%). The exams will consist of multiple choice, short answer, and essay questions. In the case of missed exams, make-ups will only be considered under the direst of circumstances and will consist of an oral test. Quizzes will consist of a short essay questions.


Nearly Required: Attendance for at least one observing session.

Dearborn Observatory has an 18.5 inch refractor that allows spectacular viewing of the planets, the moon and other objects. Observing sessions will probably be held on Tuesday evenings, but check on Wednesday (here or in class), 30 March for the day of the week for the observing sessions. There will be two sessions. Each will be one hour long and will be limited to 10 students. The first session will be held the second week of class. The times of the sessions will be announced at the end of the preceding week and the beginning of the week of the sessions. Sign up sheets will be made available in class and attendance will be taken at the sessions. You are allowed to attend more than one session. You should attend at least one session. The session will he held regardless of whether it is cloudy or not. A tour will be given in any event. Repeat attendance to achieve actual viewing is encouraged, but not required.  If you are on the border line, i.e within 1-2 percentage points of the next grade level down, and you have not gone to an observing session I’ll move you down ½ a grade,  e.g., from B to B-

General Course Outline (note, I will not cover all of each chapter)

        Week 1 (March 30-April 3)

Introduction, Read Chapters 3

o   NASA Office of Space Science - the US space facilities

o   The Naval Observatory Web Page - "the web site for those who really want to know what time it is"

o   Sky Online - courtesy of Sky and Telescope magazine

           Week 2 (April 6-April 10)  
            Read Chapters 3, 4, 5(part)

 Quiz on Friday April 10

o   Lens simulator

o   Black Body Radiation

o   Optics Simulators for the experts

o    X-ray Optics

Week 3 (April 13-17) Special Lecture on 13 April by Former Astronaut  Jeff Hoffman

Read  chapters 5(part), 16 (will emphasize part 16.6 and 16.7) 

First Mid-Term April 17  3,4,5, and 16; Review session 16 April M345 Tech 8:00-9:30 p.m.

o   Solar movies

o   SDO movie link

o   Solar structure movie


Week 4 (April  20 -24)
Read Chapters 17

Quiz April 24

o   Move your star on the HR diagram

o   Evolve your HR diagram

Week 5 (April 27- May 1)

Quiz May 1

Read Chapters 17, 18, 19 (part)

o   More about the ISM than you care for

o   A stellar birth movie

o   Triggered Star formation, chicken and egg


Week 6 (May 4 May 8)

Second Exam 2 May 8 Chapters 17,18,19 20, (part)21 ; Review session May 7 April M345 Tech 8:00-9:30 p.m.

            Read Chapters 19(part) 20, 21 (part)

o   Stellar evolution movie

o   Another evolution movie

o   Another’s lecture on SNae

o   Extensive material on SNae


Week 7 (May 11-15)

o   X-ray emitting pulsars

o   Sounds of radio pulsars

o   Black Holes

o   All Kinds of collisions

o   Neil de Grasse Tyson on falling into a black hole

o   Weird stuff inside a black hole

Quiz May 15

Read Chapter 22 (part)

Week 8 (May 18-21)

Quiz May 22

o   Lecture (> 1 hr) Black hole at the Galactic Center

o   Fun Journey to the GC

o   Star orbits around GC

Read Chapters 22, 23, 24 (part)

Week 9 (May 24-29)

o   Observable Universe with Sloan Galaxy Images

o   Observable Universe to its edge

o   Planck Satellite First Light

French film that has nor much do with the class, but is amusingRead Chapters 24(part), 25,

Third Exam Covering 21 (part) 22, 23,24, 25; Review session Sunday Night May 31, 8:00-9:30 p.m.


Happy summer vacation


The First Lecture

As a way of introduction, I would like to begin by making some general comments.

First, Astronomy is probably the oldest science. Anybody who has looked up at the sky has gazed in wonderment. Driven both by curiosity and religion, man continued to study the sky. There were some pretty important religious based questions that were addressed, such as exactly where did man and the earth stand compared to the universe. On the curiosity side, we are simply driven on and to learn more even as we learn more. For, as we delve in to the limitless universe it seems we often uncover new questions as we answer old ones. The growth in our knowledge of physics in the past 100 years has allowed us to understand a great deal about the stars, planets, galaxies and the universe at large. In the distant past when this knowledge wasn't available, astronomers had more use as astrologers. They told people the location of the planets etc. The concept of a supernatural being and how the being's existence explains the existence and characteristics of Earth has affected people's connection with organized religion and vice versa. The knowledge of astronomy was useful for debates in this area. The Copernican Revolution was a classic example. Now we enter a new era of astronomy and astrophysics where billions of dollars are spent every year on astrophysics research, and society as a whole is starting to ask tough questions such as why is this research necessary? What's in it for me? Or why do I find it interesting? And is it worth  that much money?  This has placed a requirement on the professional astrophysicist to emphasize research that connects directly to the interests of the layman rather than, perhaps, the esoteric interests of the peer group of astronomers and astrophysicists who know enough to ask detailed questions. You, as future leaders and taxpayers will have to answer the question of how much funding to give to astronomy  and astrophysics and why. Two of my goals in this course are to motivate you to want to learn this material and to teach you enough so that you will be able to make educated choices about future funding as well as to appreciate future press releases and discoveries.

There is another reason for you to take this course, however, and that is to learn how to think like a scientist. So stop to think a minute now, what does it mean to you when the TV reporter says "today scientists have announced the discovery of..." The use of the word scientist had a certain implied reliability, right? Why is that? And why do most universities require that you take an science class?  This is because you are supposed to receive some training to behave like a scientist, right? Yet mostly the astronomy, biology and geology courses that are offered are descriptive courses where the main goal is to teach jargon and facts. The facts will be useful as noted above, but beyond that this new knowledge will make you more conversant, and if your child asks you something about the sky someday you'll be able to give a concrete answer. But is this motivation enough to require that you take a science class? Probably not. It is better for you to get some training at acting scientifically. We won't be able to do this rigorously, but I hope you will actually benefit from this class.

Here are some of the things that I hope will stick with you:

(1) Be methodical and take careful notes: since this is the is the art of making reproducible results, e.g., if you tell somebody exactly how you did something, they should be able to repeat it and get the same result. As an aside here, there is implied a certain level of competency in being able to reproduce the results. I could get a very precise ski lesson and still not be able to make it down a snow covered slope in one piece. Nevertheless, detailed recording of how the measurements were done, the material was made, etc is what is needed. One of the things that makes most of us disbelieve in UFOs, leprechauns, Big Foot etc, is that the supposed observations are not reproducible in any controlled fashion. (Sure people continue to report UFOs, Big Foot etc, but there is no concrete, reproducible evidence of these things.)

2) Think deductively and critically. For example, if a marketing person calls you and tells you that if you follow their advice, you will become rich... Think about it...Why doesn't the person on the end of the line just follow their own advice? OR thinking critically: a football player a few years ago had a sore back and the team had him take 40 Advils a day.  What was he thinking? Didn't the read the bottle for directions? Also when somebody provides you with a fact that is important to you, how do they know? What is their reference, or how did they make the measurement? This will even allow you to pick out exaggerated claims such as "Scientists discover Black Hole....''. How did they know?

(3) Avoid as often as you can qualitative thinking and descriptions versus quantitative descriptions, e.g. it's a long way to Tipperary..what does "long way" mean?

(4) Always have an idea of where you are going, why are you going there and a schedule for achieving those goals. No scientific project that takes more than a few hours or days can be done on time and within budget without systematic planning, project justification, budgets etc.

As we learn about the Milk Way Galaxy we will find it is huge. And thus unlike the solar system where we can send satellites (or even people) to explore the planets, moons asteroid and comets, we can at the very best only hope to reach the nearest stars. For, at 1/10 the speed of light, about as fast as we can ever imagine achieving with a rocket,  it would take 40 years to reach the closet star.   To get a picture of our galaxy then would  take us about 10,000-100,000 years!  Clearly this in not feasible, so an interesting questions for our class are: how do we know what our galaxy looks like and what is it made up of? 


Imagine, then, for a moment  that we are intelligent amoebae living ½ way up a 20 year old oak tree trunk.  We only live for a second to two, but we live fast so we’ve developed a technology to look through the tree and well as outward. We have no hope to traveling proportionally far in the tree trunk nor do we have much motivation given our life spans.   For, even if we could achieve high velocities (for us), it would take tens to hundreds of millions of lifetime so go around the trunk once.   We have figured out via remote sensing that we are on a thing that has leaves,, and bark and branches. Then we have to look out and see if we could find  something that looks like what we think we live in. We see grass and conclude, nope, not grass. Then we see bushes, rocks and maybe even a house.  Nope, not those.  either, we conclude   Then  we see a red bud tree. Note not that either, but closer.  Our habitant is related at least. Then finally we find a 20 year old oak tree and we by virtue of establishing the distance to the oak tree, determine that its size and shape meets the description of our own tree. How we figured out distance in our own tree and then to the next trees was tricky, but we did it.

Thus for example about in the early 1800’s when astronomers still didn’t know what we lived in..  Then, the Messier catalog was made  (by M. Charles Messier) to list objects that looked fuzzy and didn’t move with respect to the “fixed” stars.  At that time, by the way,  these fuzzy objects were judged uninteresting, and  the catalog was judged useful so you didn’t mistake theses boring objects for something that looks and fuzzy and moves in the sky with respect to the background stars , ie. comets.  Ironically, now those fuzzy things have turned out to be more interesting than comets; galaxies. One of the most famous in Messier’s catalog is M31, also called Andromeda.  Probing our own galaxy and then looking at Andromeda  we have concluded that our galaxy would look a lot like Andromeda is we could fly fay enough away to take a picture.