Introduction to Astronomy and Astrophysics

Course meeting times: 10-10:50 on MWF in CNS E106

Text: Modern Astrophysics (second edition) by Carroll and Ostlie

Instructor: Thushara Perera

Office: C 007C in CNS

Office Hrs: M 4-5, W 1-3, R 1-2, F 11-noon.  If these times do not work, you can email me to set up an appointment

email: tperera

Phone: 556-3888

Course Content: Astronomy and Astrophysics

Astronomy holds a special place among the sciences.  It is the oldest science, the subject area within which the scientific method was fully utilized for the first time.  Astronomy concerns itself with the motions of objects in the sky and understanding those objects and associated phenomena through higher-level laws/truths using observational data.  What do I mean by "higher-level laws/truths?"  Astronomical findings do not always need to be explained in terms of the fundamental physical laws underlying the those processes; it is often more useful to study patterns or behaviors of a system and infer the rules it follows without trying to understand everything in terms of the laws of physics.  For instance, imagine trying to understand all of chemistry (or biology, or psychology) in terms electrodynamics and quantum mechanics, which  should be possible to do, in principle; it would take us ages to arrive at the simple results that chemists already know.  Thus, it makes more sense to describe some astronomical systems in terms of higher-level patterns and laws that we discover through observation.  In some cases, we don't even know how to explain an astronomical phenomenon in terms of the underlying physics yet.

However, there are many cases where we do understand the physics behind the astronomical process and where that understanding gives us further insights into how the universe works (i.e. the physical understanding is useful).  The study of the physics behind astronomical processes is known as astrophysics.  For instance,  Kepler's laws of planetary motion are an example of astronomical (higher-level) truths/laws resulting from the careful analysis of astronomical observations.  Later on, Newton showed that all of Kepler's laws can be derived from two fundamental laws of physics: his second law of motion and his law of gravitation.   This understanding was very useful because it explained, not just the motion of planets about the sun but of satellites (e.g. the moon) around their planets, and stars around one another.  Thus, we can say that Newton was the first astrophysicist because he used the laws of physics to explain astronomical truths.  From this, it should be clear that describing a system astrophysically (i.e. a description based on the fundamental laws of physics) is much more mathematically challenging than describing it astronomically (using higher-level laws).  Another reason why astrophysics is considered a challenging subject is because usually, to understand even a single astronomical system (e.g. the interior of a star), results from many areas of physics (e.g. plasma physics, nuclear physics, molecular physics, and even superconductivity) have to be used.  Astrophysicists need to know which laws apply in which situations. 

Course Description and Goals

Given how much material falls within realm of astrophysics---just take a look at your textbook from a side---if it fair to say that we will cover only some of the subject matter in detail.  We will learn about some subjects in an astronomical sense and others in an astrophysical sense (you now know what those terms mean).  Two themes that will become clear as we move forward:

1. We will take the time to understand how we know certain truths that we often take for granted.  For instance: Why do we think the earth is approximately spherical?  How do we know that the earth goes around the sun and not the other way around?  How do we know the actual sizes of the earth, moon, sun, and planets?
   
2. During the semester we will study two astronomical systems at a high level of technical detail, bringing in all of the necessary physics as well as the necessary mathematical and computational tools.  Then we will make predictions based on our model and check them against observational data to verify that our understanding of the system is indeed valid.  This will give us a sense of how the machinery of astrophysics actually works in its full glory!
   

One of the topics that we pick for 2 will be covered in class, during my lectures.  That topic will come from Stellar Astrophysics, which is considered the most mature (well understood) area within astrophysics, and covered in Part II of the textbook.  Thus, the two parts of the textbook that will be emphasized in lecture are parts I and II.

Your Project

The second topic for 2 will be picked by you from the list of topics below.  Come see me in my office during the first two weeks of class, so that I can give you some guidance with choosing topics.  I will ask you to pick two or three topics that interest you and, based on interest, pair you up with another student to work on one of the topics.  Your project (on the topic of your choice) will consist of three parts: 

• When the topic you chose comes up in class, you and your partner will give a presentation on that subject, in place of my lecture.  The two of you should plan a presentation, with my help and using the textbook as a starting point, that covers one class period.  If you need more time, you can have half of a second class period.  During this presentation, you will also tell us how you plan to continue with the project for the rest of the semester.
  
• Your group's continued work on the project (after learning the basics well enough to present it to the class) will usually involve either observational work at the observatory, analysis of publicly available astronomical data (e.g. from NASA), or a calculation or simulation using a language such as Mathematica or Python.  Even if you presentation does not occur 'til later, you should start this work in early October.  Don't think of this part of the project as a an independent research project---that would be way too difficult to do within a one-semester class.  Instead think of it as an extensive homework assignment where you will "get your hands dirty" by actively doing some observational or computational work to truly explore the topic of your choice in some technical detail.  During this time, you will most likely learn about and become interested in independent research projects within those fields.  You will also learn about which groups at what universities/agencies are currently leading the research in those fields.  I hope that this experience will be the beginning of a lasting involvement in astronomy/astrophysics for you (e.g. a lifelong interest or hobby, point of entry to a summer research internship here or elsewhere, or even graduate study in astronomy or astrophysics).   When you get started, I will point you to the useful resources I am aware of related to your topic.  I will reduce the amount of regular homework appropriately so that you can spend quality time on the project.  I may also give you some class time to work on these projects, if needed.  You will need to consult with me regularly so that we can find the resources you need and adjust/modify the goals of the project as appropriate.
  
• During the last couple of weeks of the semester, you will make another presentation on the progress you've made with your project.  After that, you will have some more time to polish your results before the day of the final.  There will not be a final exam.  On the day of the final, you will summarize your best and final results on the project.
  

The topics that you may choose from are:

• A holistic picture (including the lives, beliefs, and quantitative contributions) of the greek natural philosophers who shaped our early ideas of the heavens and earth
• Attempts, successes, and failures to use the transits of venus for obtaining a length scale for the solar system
• Topics related to the webinar "Chemistry on Mars"
• Capabilities and limits of the telescope(s) and cameras available at the Evans observatory (9/12)
• The Search for Exoplanets (9/21)
  
• Stellar Models: modelling the interiors of stars
  
• The Solar Neutrino Problem
  
• General Relativity and Black Holes
  
• Gravitational Waves, their detection, and their sources
  
• Types of galaxies and galaxy evolution
  
• Active Galaxies (quasars etc.)
  
• The Cosmic Microwave Background
  
• Large Scale Structure formation in the universe
  

Grade Breakdown

• Quizzes and Participation: 10%
• Homework: 30%
• Midterms (two or three): 30%
• Class Project: 30% (10% for the initial presentation and 20% for the rest of the work)

Tentative Reading Assignments

The reading must be completed prior to class.  You will be tested on he reading through pop-up quizzes.