ASTRONOMY 3150
INTRODUCTORY ASTROPHYSICS
TOPIC OUTLINE:
INTRO: THE CELESTIAL SPHERE
Intro: Fundamentals of the
Celestial Sphere
A.
Celestial positions: poles,
equator, coordinates and the telescope's equatorial mount
B.
Celestial motions and time: daily solar & sidereal, seasonal solar & sidereal,
precession and the origin of constellations
C.
Determining the "visibility" of celestial objects; finding alt, azm from dec,
RA, date, time (HW Exercise 1)
SECTION 1: GRAVITY
I.
Celestial Mechanics (Prelude 1 & Chap. 1, 12)
A.
Kepler's laws (Graphic for
properties of ellipses:
click here)
1.
law of ellipses: each planet moves in an ellipse with the Sun at one focus
2.
law of areas: the line between the Sun and the planet sweeps over equal areas in
equal time intervals
3.
harmonic law: the ratio of the cube of the semi-major axis (a) to the square of
the orbital period (P) is the same for every planet which orbits the Sun:
[ a3 = P2 ]
B.
Two body problem: deriving Kepler's laws from Newton's laws of motion and
gravitation
1.
two-body setup; reduce 2-body to motion under central force (cylindrical/polar
coordinate equations)
2.
solution to θ equation: Kepler's
2nd law (law of areas)
3.
eliminate time (t); r(θ) solutions:
Kepler's 1st law (law of ellipses) - conic sections - more than just "ellipses"
4.
derivation of Kepler's 3rd law (harmonic law [ a3 = P2 ]) - Newton's version of
"K3" verses Kepler's "K3"
a.
circular orbit example
b.
elliptical orbit example
C.
Interplanetary navigation using Kepler’s laws + more (HW Exercise 2)
II.
Determining the mass of stars:
binary systems (Chap. 12)
A.
Mass of the Sun from Earth’s orbital parameters
1.
determination of the AU (“zeroth” rung on the cosmic distance scale)
2.
parallax (1st rung on the cosmic distance scale)
B.
Binary star types
1.
observational definitions
2.
mass determination of the components
3.
mass-luminosity relation
4.
preview: Sag A*
D.
Spectroscopic & eclipsing binary systems
1.
spectroscopic binary system
a.
observational definitions
b.
minimum mass (m
sin(i)) determination of the components (double line system)
c.
single line, low mass secondary spectroscopic binary system (exo-solar planets
radial velocity method)
2.
Eclipsing binary systems
a.
observational definitions
b.
period, inclination, diameter ratio, surface temp ratio determination
c.
eclipsing-spectroscopic binary system – determining absolute values
d.
exo-solar planets transit method (HW Exercise 3)
III.
Sagittarius A* mass from stellar orbits
A.
Mass from stellar orbit S2: rp
= 1.8 x 1013m = 120 AU, P = 15.2 y
à
4.1 x 106 M8
B.
General Relativity Concepts
1.
Space-time curvature and mass-energy density
2.
Black holes and the event horizon
IV.
Milky Way mass (spiral galaxy masses)
A.
Effect of external spherical mass distribution
B.
Mass of the Milky Way - 1st encounter with “dark matter”
V.
Virial Theorem – Application to Galaxy Systems
A.
STARE black-hole masses (HW Exercise 4)
B.
Galaxy cluster mass – even more “dark matter”
1.
Deflection of light (gravitational lenses) – mapping “dark matter”
2.
Preview: The curvature of the
Universe – “dark matter” + “dark energy”
SECTION 2:
LIGHT
I.
Electromagnetic Radiation and Matter (Chap. 8)
1. Properties of waves
2. Maxwell's E&M wave equation, radiancy (= intensity)
3. Intensity inverse square law
1. Continuous spectra
2. Emission line spectra
3. Absorption line spectra
C.
Spectrograph optics (Why do they
call it “line” spectra anyway?)
1. Cavity radiation & the UV
catastrophe
2. Wien’s law & Stephan-Boltzmann
law
3. Planck equation (HW Exercise 5)
E.
Atomic structure and line spectra
(HW Exercise 6)
1. The photo-electric effect (Einstein) - light as particles
2.
The Bohr model, line wavelengths
3.
Line strengths and stellar
surface temperature (spectral type)
II.
H-R Diagrams (Chap. 13,16)
A.
Distance and brightness of stars
1.
Stellar parallax (1st rung on the
“cosmic distance ladder”)
2. Apparent & absolute magnitude and
the distance modulus
1. Vertical axis: Absolute magnitude - luminosity
2.
Horizontal axis: Spectral type
(Chap. 13)
C.
H-R diagrams; stellar evolution
and standard candles
1. Evolutionary tracks & the
life-cycles of stars
2. Interpreting the H-R diagrams of
clusters (Color-Magnitude diagrams)
III.
Climbing the “Cosmic Distance Ladder”
A.
Period-luminosity relation
(Cepheid variables)
1.
Doppler verses cosmological
redshifts
2. The Hubble “constant”
C. Supernova type Ia (SN Ia)
standard candle & the Hubble diagram “on steroids”
D.
The last note of the music from
the beginning of time – determining the curvature of the Universe
SECTION 3: Class Presentations
Presentation Topics
Student presentation
topics must be selected by Friday, Oct. 25th. Please contact Dr.
Jones for preliminary materials and references for your topic.
You may request a topic that is not shown in the list. There will be two
presentations per class period beginning on Monday, Nov. 11th, and
ending Monday, Dec. 2nd.
Each timed presentation should be between 10 – 15 minutes, with 5 minutes for
questions and discussion; a total of 20 minutes.
We will use the same evaluation rubric as Senior Seminar.
The Seminar Section is considered the final evaluation for the course and
is weighted 25%.
Topics:
1.
Adaptive optics
2.
Mass of Center of Milky Way
3.
Cosmic Microwave Background variations (curvature of the Universe)
4.
SN Ia “standard candle”
5.
Hubble Diagram – acceleration of the Universe
6.
CMB variations + SN Ia Hubble Diagram – the Cosmological Constant
7.
Parallax method for stellar distance
8.
Cepheid Period-Luminosity relation “standard candle”
9.
VASIMR plasma rocket – humans to Mars?
10.
STARE Project “reverberation” method
11.
Density wave theory of spiral arms
12.
Radio interferometry
13.
Basic radio telescope principles – NERT
14.
CCD photometry – preprocessing, mag measurement
15.
21 cm radio HI emission line
16.
NASA Fireball Network
17.
Kepler mission final update
18.
Exo-solar planet light-curve analysis
19.
Galaxy cluster mass determination from
gravitational lenses
20.
Detecting exo-solar planets