ASTRONOMY 4

Fall, 2000 Midterm #1

Study Topics

H-R Diagrams

know what the axis are

• luminosity or energy output and temperature or spectral type

what type of stars are where

• protostar, main sequence, red giant, white dwarfs, neutron stars, black holes

evolution of a solar mass star on the diagram

evolution of a large mass star on the diagram

stellar classification

• OBAFGKM, & I-V

Fundamental Particles and Forces

Particles: know their mass, charge, where it is found

Particle	Charge	Mass
Electron	-1	Light (0.5 MeV/c2)
Proton	1	Heavy (936 MeV/c2)
Neutron	none	Heavy (938MeV/c2)
Neutrino	none	Very Light (?)
Photons	none	No Mass

Forces: know what force is responsible for stellar processes

Force	Strength	Mediate	Range
Strong	4	Fusion	Within nucleus
E&M	3	Radiation	infinite
Weak	2	Radioactive Decay	Within nucleus
Gravity	1	Collapse	infinite

Pressure

know what pressure is, and what affects pressure

• motion of atoms and molecules; density, temperature

know what quantum pressure is

know the Pauli Exclusion Principle

• two particles of same state cannot be at the same place

how do you get quantum pressure

which particles can have quantum pressure

• electrons and neutrons

know how pressure affects a star

• holds up a star (like it's skeleton)

Stellar Structure

know the internal structure of each type of star listed above

• e.g. MS stars fuse H, may have a small core, large H envelope

know especially well the Red Giant

the mirror effect

onion shell structure

steps of successive nuclear fusion

• (H --> He --> C,O,N -->Fe)

Feedback mechanism and the stability of stars

• negative and positive feedback

Special Relativity

know the caveats of special relativity

• speed of light is constant

• all observers equal

know what an inertial frame is

know the results of special relativity

• time dilation (moving clocks run slower)

• length contraction (moving yardsticks are shorter)

Neutron Stars and Black Holes

know how a white dwarf turns into a Neutron star

know why there is a limit to White Dwarf mass

know what an event horizon is

Binary Stars

know the characteristics defining a binary star

• primary mass, secondary mass, orbital separation/period

know what a Roche Lobe is

know how mass transfer between binary stars occur

know what tidal forces are

Answers to the study questions:

week #1

1	c
2	d
3	a
4	b

week #2

1	c
2	d
3	a
4	a