Download Cosmic Objects – Cosmology – Study Guide

Astronomy
Name ____________________________
Cosmic Objects – Cosmology – Study Guide
You will be asked to identify the definition or recognize an example of the following. These will
be matching column or multiple choice-type questions.
Nebulas
1. Emission (or Diffuse) bright dust and gas due to hot gases (usually red or green)
2. Reflection bluish dust and gas that is light being reflected off nearby star(s)
3. Dark cold dust and gas obscuring all light
4. Planetary stellar remnant of small, dying star’s blown away atmosphere
5. Supernova Remnant hot dust and gas blown off in a supernova explosion
Stars
1. White Dwarfs dying core of a low mass star, surrounded by a planetary nebula
2. Neutron Star dying core of a medium mass star (2-5 solar masses); 10-mile diameter
3. Red Giant star that is fusing helium; off main sequence; outer layers swell outward
4. Main Sequence star that is burning hydrogen into helium; where stars spend 90% life
5. Cepheid Variable star whose brightness predictably varies; used to measure distance
6. Globular Cluster group of up to 1 million stars, usually in the halo of galaxies
7. Open Cluster in the arms of spiral galaxies; 50-1000 stars; usually young (<50 million yrs)
Galaxies
1. Spiral stars, dust and gas flattened into a rotating disk, surrounded by a halo of globClusters
2. Elliptical giant spheroid shaped group of stars, little dust and gas; usually old
3. Irregular stars with lots of dust and gas, young, place of lots of star formation
Solar System Objects
1. Planet large sphere orbiting the sun in its own path
2. Moon natural body orbiting a planet
3. Comet rock and ice on high elliptical orbit around Sun; forms a tail when close to Sun
4. Asteroid rock and metal orbiting the Sun
5. Oort Cloud spheroidal cloud of ice and rock surrounding the solar system, > 100 AU
Phenomena
1. Gamma Ray Burst most powerful explosion in the universe
2. Black Hole collapsed massive star whose escape velocity is > speed of light
3. Quasar quasi-stellar radio source; very far, very bright, and strong radio source
a. Blazar Galaxy energetic jets are aimed right at us
4. Brown Dwarf failed star; not large enough to generate nuclear fusion in core
5. Dark Energy repulsive force that is causing the universe to expand
6. Pulsar rotating neutron star, found in supernova remnants
Exploring Black Holes ppt
1. What is the Doppler effect? Change in frequency of waves (sound or light) due to the
motion of an emitting source
2. What does the Doppler effect say about the universe?
The universe is expanding; all galaxies not in a group are moving AWAY from each
other
3. Who first proposed the existence of “black holes” in 1784? Jon Michel
4. How do we see “black holes?” studying the motions of stars and hot gases
5. Different parts of the spectrum give us different clues. When looking for black holes,
what do we “see” in:
a. Optical: bright accretion disks
b. Ultraviolet: fast pulses of UV radiation
c. Radio: motion of particles
6. Describe the three sizes of black holes. Supermassive (up 1 billion Solar Masses);
Stellar (5-50 Solar Masses); Medium/Small (possibly microscopic)
Megadisasters: Gamma Ray Bursts GRB ppt
7. What are the TWO types of GRBs and what is a probable cause of each?
Long (2-100 sec) Collapsars: Giant massive stars dying and becoming a black hole
Short (<2 sec) Merger/collision of two neutron stars
8. What are TWO possible effects on Earth of a nearby (< 1000 LY) GRB?
Damage ozone layer = UV damage to Life; Global cooling due to smog formation
9. How often do GRBs occur? Once every 100 seconds (we see 1 per day)
10. How long does a GRB last? See #7 above
11. Where do we find GRBs? Deep Space (across the entire sky)
12. When were GRBs first seen? 1960’s (Compton Gamma Ray Observer)
13. Why can’t we study GRBs on Earth? Atmosphere blocks Gamma Rays
What is the Universe? (Reading)
14. Name and describe the three shapes of the universe.
Flat – infinite; Positively curved = like a sphere, closed;
Negatively curved = like surface of a saddle
15. The Big Bang is a logical consequence of _an expanding universe_.
16. What does it mean when we say, “When you gaze at the night sky, you see a universe
that no longer exists.” ? We are seeing light that has traveled to millions or even billions
of years. The sources of that light have moved or changed in the time it took light to
reach us.
Possible Bonus Questions
1. What is the name of a neutron star that has an intensely strong magnetic field?
2. What is the name of the spacecraft that studies Gamma Ray Bursts?
3. Name the American astronomer who first discovered the tool used to measure the size of
the Milky Way and other galaxies. When?