Physics of Stars
ASTR.2400.2 Winter, 2015
Faculty of Science - Course Outline
Instructor:
Contact:
Dr. I. Short, P.Phys., Assoc. Professor
ian.short@smu.ca
Office: AT324, Ph. 496-8194
Office Hours:
TR, 2:00-5:00, AT324
-----------------------------------------------------------------------------------------------------------------------------Lectures:
10:00 am - 11:15 am, TR, Atrium (AT) 306
Please arrive early and plan to begin at 10:00!
-----------------------------------------------------------------------------------------------------------------------------Course Description
This course reviews stellar properties, spectral classification and the Boltzmann and Saha equations,
radiative transfer and stellar atmospheres, the equations of stellar structure, and the interiors of hydrogen
burning stars such as the Sun.
3 credit hours
Pre-requisites:
ASTR 2100, 1100
Required Materials: Text: An Intoduction to Modern Astrophysics, 2nd Ed. Carroll and Ostlie
Spectral atlases from course WWW site: www.ap.smu.ca/~ishort/ASTR2400/
Course Content and Learning Outcomes
Chapter 8
Spectral classification of stars
Physical basis for spectral classification: MK classification; gas in thermodynamic equilibrium: the
Maxwell-Boltzmann velocity distribution, the Boltzmann excitation equilibrium, the Saha ionization
equilibrium; Hertzsprung-Russell Diagram: luminosity classification of stars; chemical abundance and
the curve of growth (COG); spectral line formation
Chapter 9
Stellar atmospheres
The radiation field: intensity and mean intensity, energy density, Blackbody radiation, flux, radiation
pressure
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Gas opacity: gas in thermodynamic equilibrium (again), extinction coefficients, mean free photon path,
optical depth, atomic transitions, mean opacity
Radiative transfer: emissivity, the radiative transfer equation, the source function, blackbody radiation,
the plane-parallel atmosphere, the Eddington approximation, the gray approximation, the EddingtonBarbier relation, application: limb darkening
Spectral line profiles: line strength and equivalent width, line broadening, the Voigt profile, the curvae
of growth and chemical abundance determination
Chapter 10
Stellar interior structure
Hydrostatic equilibrium (HSE): pressure scale height
The pressure equation of state (EOS): ideal gas law, mean molecular weight, radiation pressure
Stellar energy generation: Kelvin-Helmholtz (gravitational) contraction, nuclear fusion, reaction rates,
energy conservation, nucleosynthesis, H fusion, fusion of heavier elements
Energy transport: radiation transport; convection: thermodynamics, mixing length theory
Stellar structure modelling: the constitutive relations, boundary condition, the Vogt-Russell theorem
Final exam: Exam week - TBA
Essential review topics
It is critical that you have some prior familiarity with the following:
Chapter 3: The magnitude scale, blackbody radiation, the quantization of energy, the colour index (BV)
Chapter 5: Spectral lines, photons, the Bohr model of the atom
Methods of Course Delivery
Lecture.
Marking Scheme (Academic Regulation 4)
Component
Weight
%
Assignments
Regular/bi-weekly
25
Comments
2
Lab exercises
25
Mid-term exam
15
Likely date: Tues 25 Feb
35
Final Exam
Scheduled by the Registrar during the formal exam period.
SMU Grading system (from Undergraduate calendar):
A-: 80-84.99, A: 85-89.99, A+: 90-100
B-: 70-72.99, B: 73-76.99, B+: 77-79.99
C-: 60-62.99, C: 63-66.99, C+: 67-69.99
D: 50-59.99
F: 0-49.99
Academic Integrity
Students are encouraged to consult the Academic Integrity and Student Code of Conduct sections of the
Academic Regulations in the Academic Calendar, in order to be well informed on the consequences of
dishonest behaviour. http://www.smu.ca/webfiles/UGcalendar2013-2014.pdf
Homework: Under SMU academic regulations it is a serious offence to present as your own work that
is taken or copied, in whole or in part, from another source or sources, including other current or
previous students, web sites, and books or other publications, or to provide your work to others knowing
that they will present it as their own. In this course this applies to home work problem sets.
Tests and exams: Under SMU academic regulations it is a serious academic offence to seek knowledge
of the contents of a test or exam in advance of taking it, including occasions when taking a make-up, or
to provide such knowledge to other students who have yet to take the test. The safest course is to refrain
from discussing in any way at all a test or exam with a student who has yet to take it.
Special circumstances: Under SMU academic regulations it an academic offense to falsify or to
exaggerate special circumstances such as illness, accidents, and family emergencies to obtain special
consideration for due dates, test and exam dates, etc.
Late Submissions Assignments are always due in class on the due date. Credit cannot be given for late
work unless the Instructor has received timely notification of a valid special circumstance.
Missed Tests Make up exams are only allowed in the event that you have a valid, documented excuse for
missing the exam, such as a medical incapacity or family emergency. Note that make-up final exams
must be scheduled through the Dean of Science office!
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Note: Under Science Faculty regulations, students requesting a make-up exam or extension must
complete and sign the Science Declaration of Extenuating Circumstances form, which then gets filed at
the Dean’s office.
In Case of Emergency
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“Saint Mary’s classrooms, in the Sobey Building, Loyola Academic, Library, Atrium and Science, are
equipped with a two stage alarm that will provide both an alarm and verbal instructions over the
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The Tower, McNally, Burke and Student Centre are equipped with loudspeakers that will sound bells
during a fire situation during which you must leave the building. In the event of an emergency, all the
above noted buildings are equipped with loudspeakers and you will be told to evacuate the building or
seek shelter in place (your current location). It is important that you follow the instructions given
through the alarm system. If you are instructed to evacuate, leave immediately. The houses ( 867 Robie,
883 Robie, 5960 Inglis, 5907 Gorsebrook and 5920 Gorsebrook) and 980 Tower Road are equipped with
a fire alarm system that will sound bells for a fire situation during which you must leave the building”
Other emergencies:
An official SMU video describing various emergency messages you might hear over the PA system, and
the required response from everyone:
http://vimeo.com/47216656
Password: safe
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