EXAM 2 REVIEW SHEET

Astronomy 110: Fall 09: Monday October 12, 2009

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THE SUN: INTRODUCTION

• Appearance of the Surface: sun spots (umbra and penumbra), limb darkening
• Anatomy of the Sun: core, radiation zone, convective zone, photosphere, chromosphere, corona, solar wind
• The Convective Zone: convective transport, granulation, supergranules
• Photosphere: where light escapes star, low density creates absorption lines
• Chromosphere: spicules, hot gas, emission lines
• Corona: low density, 1 million degrees
• Flares, prominances, magnetic loops, coronal mass ejection (CME)

THE SUN: MAGNETIC PROPERTIES, SUNSPOT CYCLE

• Magentic fields and force on charged particles, motion of trapped particles, response of the field lines
• Evidence for strong magnetic field in sunspots, Zeeman splitting
• Sunspot cycle (11 years), the Maunder butterfly diagram (behavior of sunspots with time)
• Differential rotation
• Sunpots: pairs, east-west alignment, opposite magnetic poles, polarity opposite about solar equator
• The Babcock model of the sunspot cycle (why is this a model, and not a theory?)

• Hypothesis driven science: observation, question, hypothesis, prediction, test, (hypothesis rejection of refinement)
• A hypothesis cannot be proven correct, only proven wrong (leading to rejection) or partially wrong (leading to refinement)
• hypothesis, models, theories, laws: know the what each is, know the difference between them.

THE SUN: ENERGY GENERATION

• Core properties: temperature, plasma state of matter, high speed of particles, mostly hydrogen (protons and electrons)
• Hydrostatic equilibrium: pressure gravity balance
• Four forces of nature: gravity, Nuclear fusion: introduction of strong nuclear and weak nuclear forces
• Nuclear Fusion:the Coloumb Barrier, role of strong nuclear force, role of weak nculear force, antimatter, neutrinos
• The solar neutrino problem and its resolution
• The net reaction of hydrogen fusion: 4 hydrogen -> 1 helium + Energy, mass loss in the process
• How is the energy released? Einstein's energy-mass equivalency, E=mc² (know how it applies)

STARS I: INTRODUCTION

• intrinsic versus observed properties
• intrinsic properties: luminosity (L), mass (M), size (R), teperature (surface T)
• know how we measure each of these intrinsic properties
• observed properties: brightness, distance
• inverse square law of light, how brightness depends on distance (closer=brighter, farther=dimmer)
• measuring distance: how you do it; parallax, parallax angle, parsec (=3.26 ligth years)
• measuring brightness, how you do it
• measuring masses: how you do it; need for binary star systems, use of Doppler shift
• The H-R Diagram I: luminosity versus temperature, the main sequence, red giants and supergiants, white dwarfs
• measuring radius: energy per unit area (~T⁴), number of unit areas (~R²), use of L~R²T⁴
• The H-R Diagram II: location of sun, trend of radius on diagram,
  regions of "small & hot", "small & cool", "giant & cool", and "large & hot"
• Spectral sequence: O, B, A, F, G, K, M, is a temperature sequence
• Main sequence stars: mass-luminosity relation, main sequence is a mass sequence too
• Main sequence is: a temperature, mass, size, and luminosity sequence (this is not true for red giants and white dwarfs)
• Main Sequence: life times, high mass = short lived, low mass = long lived

NOT COVERED: (so don't study this stuff- I am just clarifying for you)

• broadening of absorption lines in compact statrs
• surveys of stars: how many of each type there are

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