AS414 Solar and Space Physics

Course Description

The temperature of the sun’s surface is 4000K-5000K, but just outside the surface, in a region called the corona, the temperatures exceed 20 million degrees K. The mechanism that heats and sustains these high temperatures remains unexplained. Nevertheless, these high temperatures cause the corona to expel vast quantities of material, creating the solar wind. This solar wind travels outward from the sun interact- ing with all solar system bodies. When the solar wind approaches planet Earth, it com- presses and distorts the region surrounding the Earth dominated by the Earth’s magnetic field called the magnetosphere. The magnetosphere channels the solar wind around most of the Earth’s atmosphere and also into the polar regions. This channeling process drives large currents around the Earth and into the high latitude atmosphere, the partially ionized region called the ionosphere. These processes frequently energize particles creating the Earth’s ring current, the radiation belts, and send energized particles crashing into the Earth’s upper atmosphere creating the Aurora Borealis. The field of space physics studies physical phenomena from the Sun’s outer layers to the upper atmospheres of the planets and, ultimately, to the point where the Solar wind’s influence wanes. Understanding this region enables us to have a space program and to communicate through space. It also gives insight into plasma processes throughout the universe. The goal of this course is to provide an introduction to space and solar physics. Since this region is predominantly filled by plasma and electromagnetic energy, a substantial amount of time will be dedicated to learning plasma physics. This course is one of two 400-level astronomy courses that serve as capstone electives for astronomy majors. It is also appropriate for physics majors and engineering students who meet the prerequisites.

Mechanics: Times, Dates, & Places

Lecture Time and place: Tuesday and Thursday 12:30-2:00pm in CAS 502 Instructor: Meers Oppenheim, Oﬃce: CAS 517, Work phone: (617) 353-6139 Home phone: (617) 965-7345, FAX: (617) 353-5704, email: [email protected], www: bu-ast.bu.edu/∼meerso/, calendar: http://calendar.yahoo.com/meerso Course WWW page address : At http://courseinfo.bu.edu/courses/08sprgcasas414 a1/ you will be able to see your grades and obtain copies of assignments Oﬃce hours: Wed. 9:00-10:00, Fri. 12:00-1:00 3:00-4:00pm or by appointment Exam dates: Midterm - March 20 (in class), Final Wed., May 7 9am-11am

1 Prerequisites

PY 355 or equivalent (Intro to Partial Diﬀerential Equations, vector calculus, transform theory (ie., Fourier). You should know the material from PY 251, 252 or 211, 212 well and, preferably have a junior level Intro to Electromagnetics or circuits class.

Grading

• Problem Sets (25% of grade)

– Weekly problem set assignments – Solutions will be handed out at the time of an assignment’s due date in order to provide immediate feedback. Hence, no extensions or late problem sets will be accepted. – Students may work in groups but must write up solutions individually. – Recommendation: students should initially attempt problems individually. – To receive full credit on a problem, a problem set must include a reasonably clear ex- planation of the method used to obtain a solution. Not every problem will be graded. Approximately only 25

• Midterm test in class (25% of grade) • Final exam (35% of grade) • End of Term Project (7.5% of grade) In the last few classes students will examine some “mystery data sets”in teams and develop theory or theories explaining their implications. The students will both describe these theories to the rest of the class and write their results up in the form of a short scientiﬁc paper. • Class participation (7.5% of grade)

– During each recitation 2 students will demonstrate how a problem is solved to the rest of the class. – Day to day participation

Bibliography

Assigned text: Basic Space Plasma Physics by W. Baumjohann and R. Treumann Secondary text: Introduction to Space Physics by Kivelson and Russell Another space physics book: Introductions to the Space Environment by Thomas F. Tascione Good Electromagnetism textbook: introduction to Electrodynamics by D. Griﬃths More advanced text: Introduction to Solar System Plasmas by Thomas E. Cravens Basic Plasma book: Introduction to Plasma Physics and Controlled Fusion by F. Chen More advanced space oriented plasma physics book: Plasma Physics by Sturrock (also, costs less than $30) Ionospheric Physics book: Ionospheres by Schunk and Nagy

Course Outline

I. Introduction A. Introduction to Space Physics (B&T Ch. 1, K&R, Ch. 1, 2) B. Review of Electromagnetic Theory

2 C. Single Particle Motion (B&T Ch. 2, Tascione, Ch 1.) D. Conserved quantities and adiabatic Invariants (B&T Ch. 2.5, 3) E. Introduction to the collective behavior of charged particles: 1. Plasma Physics (B&T Ch. 7, Tascione, Ch 1.) 2. Plasma Fluid Behavior (B&T Ch. 7.3-7.5) 3. Introduction to MHD (B&T Ch. 7.3-7.5, Tascione, Ch 1.) II. The Sun (B&T Ch. ?, Tascione Ch. 2; K&R Ch. 3; Cravens Ch. 5) A. Structure of the Sun B. Solar Atmosphere & Radiation C. Solar Magnetism & Solar Cycle D. Solar Activity: Flares, Prominences, etc. III. Solar Wind (B&T Ch. 8, Tascione Ch. 3; Cravens Ch. 6 & 7, K&R Ch. 4 & 5) A. The origin of the Solar Wind: The Solar Corona & Composition B. Failure of the hydrostatic solution C. Parker solar wind equation and solution D. Solar Wind Magnetism and shocks E. The Heliosphere and Heliopause F. Solar Wind Interactions with Solar System Bodies IV. Geomagnetism (B&T Ch. 3, Tascione Ch. 4) A. Dipole Field of Planets B. Magnetic Structure of Planets C. Magnetic variations V. Magnetospheric Physics (B&T Ch. 5, Tascione Ch. 5), K&R Ch. 6, 9, 10, & 13, Cravens Ch. 7 & 8) A. Solar Wind – Magnetospheric coupling B. Shocks: Fluid shocks, collisionless shocks & the bow shock C. Magnetic Currents & Convection D. Magnetospheric structure E. Magnetospheric – Ionospheric coupling F. Magnetospheric Dynamics VI. Planetary Neutral Atmospheres (Tascione Ch. 6) A. Composition, Structures, & Temperatures B. Atmospheric Dynamics VII. Ionospheric Physics (B&T Ch. 5, Tascione Ch. 6, 7 and 8; K&R Ch. 7 & 14; Cravens Ch. 7) A. Ionization Production & Losses B. Ionospheric Structure & Chapman Layer Theory C. Diﬀusion & Transport in the ionosphere D. Radio Wave Transmission, Reﬂection, and Scattering E. Equatorial Ionospheric Physics F. Auroral Ionospheric Physics VIII. Spacecraft Issues and Hazards (Tascione Ch. 10) A. Spacecraft charging

3 B. Spacecraft drag C. Radiation hazards in space to man and machine IX. Space Weather X. Analyzing a Mystery Data Set