 |
|
FIRST
EXAM AY 101 REVIEW for this document in a printable format, click here: For a printable practice test, click here: General order of size and distances of things in the universe Things you see in the sky: (What governs this?) tides on earth's rotation and moon's orbit. Time moon rises and sets at different phases. Ancient Greek Astronomers: a sphere. and moon compared to earth. Revival of heliocentric theory. different from and similar to Ptolemy's and Aristotle's views. cause elliptical orbits and "law of areas" discovered by Kepler.
masses of astronomical objects. Electromagnetic Radiation: Definitions: wavelength, frequency, speed of light. Different types: radio, IR, visual, UV, x-ray, gamma rays differ only in wavelength. Have rough idea of wavelengths. Inverse square law. Know calculation of simple examples. Doppler effect: from motion of source and/or observer. 90 degree motion no effect. Know formula and simple use of it. Reflection. Refraction. Diffraction. Know difference between
these. Understand prism effect (color fringes) of refraction. Telescopes: lens and mirror formation of an image. Know the two basic functions of a telescope; (1) to show fainter objects than eye. Know the relation between light gathering power and objective size. (2) to show finer detail than eye. Know the relation between resolving power and objective size, i.e. the larger the objective less diffraction blurring. Also shorter wavelength less diffraction blurring. No chromatic aberration (color fringes) in mirror telescopes in contrast to lens telescopes. In achromatic refractors color fringes not so bad. Reflectors are cheaper than refractors. Understand equatorial mounting of telescope. Radio Telescopes: The relation between wavelength of radio
waves, dish size and resolving power. |
|
SECOND
EXAM AY 101 REVIEW For this document in a printable format, click here: Planets: Holding an atmosphere; Weaker surface gravity means lower escape velocity and thus more difficulty holding different gases in atmosphere. Earth vs. Moon. At higher temperatures, molecules move more rapidly and are harder to hold. Planets or satellites near Sun have more trouble holding than those farther away. Mercury vs. Saturn's moon Titan. Small mass atoms or molecules are harder to hold. Earth has no H or He. Earth: Internal structure of earth. Seismic study, P, S waves and study of earth's liquid interior. The active Earth. "Floating" of continents on higher density ocean floor rocks. Plate tectonics (continental drift). Bending of rocks and mountain building in plate/continent collisions. Differentiation of earth. (Like an onion according to density.) Earth's Moon: Contrast with Earth. Why so different? Daily cycle of temperature. Lack of atmosphere due to lower escape vel. due to low mass. Craters. Central peaks. Rays. Rilles. Lunar "seas", maria. How these were formed. Why we see few craters on earth. Internal structure and activity of Moon: Contrast with Earth. Greater rigidity due to faster cooling due to Moon's greater surface to mass ratio compared to Earth. Every difference due to Moon's smaller mass. Age of Earth and Moon: How old? Radioactive dating. Rocks on moon typically much older. Why? Collision theory of formation versus capture or fission. Solar system components: relative masses, locations. Sun, planets,
satellites, asteroids, comets, meteorites, meteor showers. Factors determining conditions on planets, satellites, etc.: Mass,
escape velocity and atmosphere as for Earth and Moon. Greenhouse effect can raise surface temp. if atmospheric comp. is right. (contrast Earth and Venus). Clouds help even out day-night temperature (example Earth and Moon). Low mass implies greater internal cooling and crust inactivity as for
Earth and Moon above. How were Uranus, Neptune, Pluto discovered? Rings: Which planets have them? Roch limit. What are they made of? Features in rings. Asteroids: How discovered. Rough size. Relation to meteorites. Kinds of meteorites: Iron, Stone and Chondrites. Formation of first and second kinds from third via melting, differentiation, and collision of large asteroids. Comets: Orbits, appearance, structure and composition. Halley's comet as an example. The Oort cloud. Role of Jupiter in capturing comets into smaller orbits or ejecting from Solar System. The Solar Nebula theory of the formation of the solar system. Events. Support evidence. Modern observations of solar nebulae and fact that planets have been detected around other stars. Spectroscopy: Continuous spectrum from "thick" gas or solid. Line spectra from thin gas. Conditions of formation of Emission line
spectrum, Absorption line spectrum. How astronomers deduce the composition,
temperature, magnetic fields of celestial objects from their spectra.
Zeeman effect. Spectral Types of Stars. Stars generally have absorption line spectra.
Spectral class differences are primarily due to differences in temperature.
Different spectra from diff. degrees of excitation, ionization, and
breakup of molecules. Estimating Distances of Stars: Parallax, baseline used, dparsecs =
1 where parallax is measured in seconds of arc, What are: AU, Light year, parsec. 3.26 light years = parsec The distance limits of measuring distances by parallax accurately, about 500 parsecs (Hipparcos satellite) Comparison of 500 pc to size of just our galaxy.
Magnitudes : Originally classification by eye of brightness classes of stars, apparent mag. m, m = 1 bright, m = 5 dim. Extension to negative, i.e., very bright. More than 6 dimmer than the eye's limit. Differences in magnitude are multiplications in intensity, i.e., energy/sec cm2 we get from a star. 1 mag. brighter means about 2.5 x previous intensity; 5 mag brighter
is 100x; 5 mag dimmer 1 ; Double Stars. Know the kinds, how they are detected. Understand the importance of double stars in determining stellar masses via Kepler's 3rd law (visual, spectroscopic binaries). Masses and even sizes of stars can be determined for eclipsing binaries. Understand how this can be done for simple case. Understand the mass luminosity relation. Know the sun's luminosity compared to most other stars. HR Diagram - Understand: Sun's rotation 25 days at equator, slower nearer poles. This probably
is related to sunspot cycle. Limb darkening, sunspots, granulation.
Plages, flares, prominences, sun spot cycle, 11 years. Magnetic field
cycle 22 years. NS polarity leading and following spots in pairs. |
|
Final Exam Review AY 101 Exam 3 Review Formation and Evolution of a star on HR diagram: Stages Protostar, Main Sequence, Red giant Low mass: planetary nebula thrown off => white dwarf High mass: supernova, pulsar or black hole (?) Events inside star in both high and low mass cases. High mass does everything faster. " How will the world end 5 billion years from now? " The change in the elements present in the universe, "genealogy" of elements in your body. " What is a white dwarf/pulsar? " Observational evidence for star evolution, HR diagrams of star clusters. Young vs. Old. Main sequence "turn off" points. Black Holes: Chandrasekher limit to mass of white dwarfs. Upper mass
limit for neutron stars. The distribution of stars in our galaxy as deduced from the observation
of the Milky Way by Herschel. What is the size of our galaxy? Understand stellar populations I (young) and II (old) and ideas about
the formation of our galaxy and changes in it during its life. Mysterious
nucleus of our galaxy. What is observed there? Why can't see it with
visible light? Why radio, IR? |