AY C10 / L&S C70U Fall 2006 Nicholas McConnell

Matching

1. This is an intrinsic property of a star that depends on its temperature and radius.

2. This is an observed property that depends on a star’s temperature, radius, and distance.

3. This is an angular method of determining distances for nearby objects.

4. This is a term for a bright object with very high redshift.

5. These galaxies are usually old and are prevalent in galaxy clusters.

1. Nothing can escape a black hole within this distance.

2. This is the region in which work must be extracted from a rotating black hole.

3. This supports white dwarfs, brown dwarfs, and neutron stars from self-collapse.

4. This can occur when a giant star accretes mass onto a white dwarf.

5. This describes the relationship between galaxies’ distances and their apparent radial speeds, which occur as a result of the universe’s expansion.


A. Black Hole

B. Brightness

C. Luminosity

D. Spiral Galaxies

E. Elliptical Galaxies

F. Globular Clusters

G. QSO

H. Parallax

I. Cepheid Variable Stars

A. Type Ia Supernova

B. Type II Supernova

C. Gravity Pressure

D. Degeneracy Pressure

E. Schwarzschild Radius

F. Ergosphere

G. Dark Matter

H. Dark Energy

I. Hubble’s Law


AY C10 / L&S C70U Fall 2006 Nicholas McConnell

True or False

1. The night sky is mostly dark because we can only see stars within about 13.8 billion light years of us.

2. The “rotation curves” that plot stars’ orbital speeds versus their distance from their galaxy’s center initially surprised astronomers by suggesting that large amounts of invisible matter exist in the galaxies’ outer regions.

3. Every galaxy in the universe is moving away from the Milky Way.

4. It is theoretically possible to outlive your peers by traveling near (but not crossing) the event horizon of a black hole and returning, because in this process you will age more slowly than everyone on Earth.

5. Gravitational lensing does not support the theory of dark matter, because we see galaxy clusters near the line of sight to gravitationally lensed objects.

6. A quasar with a redshift of one (z = 1) is receding from us at the speed of light.

7. Cepheid variable stars and Type Ia supernovae are examples of “standard candles” which have a known luminosity and thereby allow astronomers to determine precise distances to galaxies outside our own.

8. Quasars are thought to come from super-massive black holes accreting matter because they produce large amounts of energy throughout a volume thousands of parsecs across.

9. At the largest observable scales, the universe appears the same in all directions. This is a result of the Milky Way’s special position at the center of the universe.

10. Neutron stars can be more massive than white dwarfs because neutron degeneracy pressure is stronger than electron degeneracy pressure.
Short Answer

1. A transparent sphere 1 parsec in diameter glows for a split second over its entire surface. How long (approximately) does the glow last for an observer outside the sphere?

2. What is a WIMP?

3. Which of the following are presently expanding? Circle all that apply.

Earth Solar System Milky Way Galaxy Cluster Cosmic Void Universe

A Blast from the Past (more short answer)

4. What are three stages a 5-solar-mass star goes through after it leaves the main sequence?

5. What quantities go on the horizontal and vertical axes of the H-R diagram?

6. You crack open a glowstick and throw it into a nearby black hole. What are two things you observe as it approaches the event horizon?

7. Jupiter’s moon Callisto has lots and lots of craters, whereas another moon, Io, has almost none. What does this tell us about Io and Callisto?

8. During what lunar phases are tides on Earth the most exaggerated?

9. What is spherical aberration, and how is it corrected?

10. Why do stars twinkle?

11. Suppose moon Angel orbits planet Buffy with a known period and semi-major axis. Which law do we use to determine Buffy’s mass, and what approximation must we make?

12. How long is the Sun’s magnetic cycle, and how many activity/sunspot maxima does it contain?

13. What causes emission lines?

14. What is the moon’s phase during a solar eclipse?