AS102 -The Astronomical Universe

Instructor: Professor Tereasa Brainerd

TAs: Ren Cashman & Katie Garcia

AS102 - Major Topics

• Where are we (earth, sun) in the universe?

• What are stars?

• How are stars born, how do they live out their lives and how do they die?

• What is the Milky Way?

• What are galaxies, and what can they tell us about the universe as a whole?

• Has the universe always existed? If not, how did it begin?

The boring details…

Class web page is http://firedrake.bu.edu/AS102/AS102.html

Textbook: Stars, Galaxies & Cosmology (5th edition) by Bennett, Donahue, Schneider and Voit

Grade Breakdown:

Labs (best 5 of 6 day labs + 2 night labs): 25%

Homework (approx. 10, 2 lowest scores dropped): 15%

Midterm Exams (15% each, best 2 of 3): 30%

Final Exam: 30%

In-class “minute papers”: 5%

Day Labs - Rooms B4 & 606

Text of day labs will be posted on the course web page.

You are responsible for printing out hard copies of the labs and bringing them to your lab section!

Luminosity & Brightness (B4)

Parallax (B4)

Gravity (B4)

Spectroscopy (B4)

Stellar Spectra (Computer Lab, 606)

Hubble Law (Computer Lab, 606)

Next week: 2/19-2/21 will be orientation and math review in lab sections.

Night Labs - Roof of CAS Building

Every CLEAR Monday, Tuesday, and Thursday night starting at 8:30pm

Call 617-353-2630 after 6:00pm for status of night labs.

Night Lab #1 - must attend one session between 01/19 and 03/4

Night Lab #2 - must attend one session between 03/15 and 04/27

Night lab reports are due by 5:00pm on the day after the last scheduled opportunity to do the lab (03/05, 04/28)

The eastern view from the roof.

Notice the red brick wall on the bottom and the concrete wall to the right.

Wear lots of warm clothes (including a hat and gloves)! You will be outside on the roof for about an hour.

Bring a small flashlight! It will be dark, and you will need to write things down during the lab.

Get your night labs done as early as you can!

• Night lab #1 is only offered before Spring Break

• Night lab #2 is only offered after Spring Break

• If you wait until the very last night to go up to the roof, and it happens to be cloudy (or snowing) that night, you’re out of luck and will get a zero on the night lab

Homework Assignments

• will be due about every other week

• will be posted on course web page

• hand in using the “Homework Box” in the main Astronomy Office (Room 512/514)

• your two lowest scores (including zeros due to illness) will automatically be dropped

• late homework is not accepted

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In-class “Minute Papers”

• Last 5 minutes of class (12:15pm to 12:20pm) write a few sentences on one of the following: something you found particularly interesting in the day’s lecture, something you found particularly confusing in the day’s lecture, questions you have about topics that were covered in the day’s lecture

• Use a full-sized sheet of paper (8.5”x11”)

• Be sure to print your name clearly

• You can miss up to 3 minute papers (due to illness or family emergency) without it affecting your grade

Physics & Mathematics

• Astronomers use laws of physics to interpret observations of the universe

• Physics is a mathematical description of nature

• Focus will be on qualitative understanding, but will be times when we need to use mathematics

• Math will be at level of high school algebra

• Will practice ratios, units conversion, powers of 10 next week in lab

• Get a copy of Prof. Marscher’s math primer from the course web page

How to succeed in this course…

• Come to class every day, do the labs, do the homework, and hand everything in on time

• Read along in the book (see the lecture outline in the syllabus)

• Start studying early for exams

• Ask lots and lots of questions!!!!

Exam Dates

• Midterm #1 - Thursday, February 11

• Midterm #2 - Tuesday, March 23

• Midterm #3 - Tuesday, April 20

• Final Exam - Tuesday, May 5 (9:00am - 11:00am)

Astronomy as a Science

• What is the “scientific method”?

• What makes a good “theory”?

• Does the scientific method have an endpoint? Why or why not?

• In what way is astronomy a “passive” science compared to other sciences (e.g., chemistry, biology)?

Learning about the Universe(where do the data come from?)

It’s all about LIGHT!

Light comes in different “colors”

Light interacts with matter

The Solar System

Sun is a perfectly ordinary, garden-variety star. Mass of 2x1030 kg, about 5 billion years old.

Earth is one of 8 planets that orbit the sun. Planets closest to the sun are hard and rocky. Planets farthest from the sun are huge gas balls. Is there anything special about the Earth’s location?

Stars in the Night Sky

Look closely at this picture on the course website. The projector does not do it justice!!

What differences might you see? Do all stars seem the same?

Baby Stars

Star Guts

The Milky Way

Time exposure image taken at the Cerro Telolo observatory in Chile.

What’s the little bright blob on the horizon?

Our home galaxy is called the “Milky Way Galaxy”. It is a vast collection of stars, gas (mostly hydrogen) and dust.

M31 (the Andromeda Galaxy)our “sister” galaxy

Like the Milky Way, M31 is a spiral galaxy where most of the stars reside in a thin disk.

The sun resides in the outer reaches of the Milky Way’s disk.

Any idea where all the stars you see around M31 are actually located?

M51 (the Whirlpool)

Bright blue stars are extremely young

Bright pink blobs are hot hydrogen gas

Notice how they all fall along the spiral arms!

Take a look at this on the course web page. This is one of the most beautiful galaxies in the universe!!!

Not all galaxies are spirals

M87 - a giant elliptical galaxy

The Large and Small Magellanic clouds (irregular galaxies)

The universe is full of galaxies!

An image of an essentially random region of the sky.

There are over 2000 galaxies in the image, and in the entire universe there are at least 100 billion galaxies in the observable universe.

Minute Paper

A few sentences on one of the following:

* something you found particularly interesting today

* something you found particularly confusing today

* questions on things from today that you would like to know more about

Be sure to PRINT your name legibly