問題一覧
1
According to the Cosmological Principle, the universe:
is isotonic and homogeneous
2
When astronomers say the universe is isotonic, they mean:
the universe looks the same in every direction
3
The Great Wall:
is composed of galactic superclusters
4
Voids are:
regions in the universe found between the filaments of superclusters
5
Which of these show the levels of organization of the universe from smallest to largest structures?
galaxies, groups, clusters, superclusters, filaments, walls
6
Which of the following is not true about Our Local Group?
it has about one thousand member galaxies
7
_____ can occur when a huge amount of matter, like a cluster of galaxies, distorts and magnifies the light from distant galaxies that are behind it but in the same line of light.
Gravitational Lensing
8
_____ are the basic "units" of structure in the universe.
Galaxies
9
Einstein considered the introduction of the Cosmological Constant:
the biggest blunder of his life
10
What property of a star determines whether, or not, it will become a Black Hole?
mass
11
_____ prevents the complete collapse of a White Dwarf, and _____ prevents the complete collapse of a Neutron Star.
Electron Degeneracy Pressure, Neutron Degeneracy Pressure
12
During the process of _____ , electrons combine with protons to form neutrons, and eventually, Neutron Stars.
Photodisentergration
13
Black Holes evaporate slowly, 10^63 years, by emitting:
Hawking Radiation
14
Simply put:
Black Holes warp Space and Time
15
What is a Pulsar?
a rotating neutronnstar that emits radiation in a narrow beam
16
At the end of the semester, a special friend gives you a piece of gold jewelry, a present to celebrate passing your astronomy class. Where did the gold come from?
it formed during the process known as Nucleosynthesis
17
According to Einstein's Law of Time Warp:
'Everything likes to live where it ages most slowly, and gravity pulls it there'
18
After the core of a massive star becomes a neutron star, the rest of the star's envelope:
explodes outward as a Type II supernova
19
What happens if a White Dwarf star exceeds the Chandraskhar Limit, 1.44 solar masses?
the core will detonate as a Type IA Supernova
20
The Orion Nebula is:
a large cloud of gas and dust illuminated but the light of newly formed stars within it
21
Which of these stars will take the shortest amount of time to go from the earliest protostar stage to the main sequence?
a star with 15 M ●
22
A Herbig-Haro (HH) object is:
created as polar jets from protostars collide with a nearby cloud of interstellar matter
23
Core energy production in protostars is accomplished through:
the Kelvin-Helmholtz mechanism
24
Why is it so difficult for astronomers to observe protostars?
all of the above
25
Which of these best describes open clusters?
hot, young, blue stars, with small populations (10-500), found in spiral arms of galaxies
26
At the end of the proton-proton chain, nuclear fusion, 4 hydrogen nuclei have been converted into:
a helium nucleus
27
When did scientist begin to understand how the Sun produces energy?
The process was not well understood until the 1930's
28
What are the properties of a Main Sequence star?
Hydrostatic Equilibrium, Thermal Equilibrium, Hydrogen core fusion
29
If the 'fuel' for nuclear fusion is hydrogen, and the Earth's oceans are filled with water, which contains hydrogen, all being jostled together, why isn't hydrogen fusion occurring in our oceans
for hydrogen nuclei to fuse, they must get very close to each other, by moving very fast and be exposed to high pressure
30
Which type of star has the lowest density and the least amount of pressure in its atmosphere?
subgiants
31
The luminosity class of a star tells the astronomer
whether the star is a supergiant, a giant, or a main-sequence star
32
Which of the stars in Diagram 1-3 has brightest Luminosity?
Alnilam
33
In an H-R Diagram, which star is found in the region designated for white dwarfs?
Sirius B
34
The reason absorption lines of stars change with different luminosity classes is because:
the widths of the absorption lines are density and pressure sensitive
35
Which two factors are required to determine the Luminosity of a star?
surface area and temperature
36
Which of the following types of star is the coolest (has the lowest surface temperature)
M
37
If hydrogen is the most common element in the universe, why do we not see the lines of hydrogen in the spectra of the hottest stars?
in the hottest stars, hydrogen atoms are ionized, and so there are no electrons to produce lines in the spectrum
38
Astronomers arrange the stars into groups called spectral types (or classes) according to the kinds of lines they find in their spectra. These spectral types are arranged in order of:
decreasing surface temperature
39
Imagine two stars. Star A has a temperature of 5000K and has a radius of two solar radii, Star B has a temperature of 10,000K and has a radius of two solar radii. Which Star is brighter? and how many times brighter than the dimmer star?
Star B, 16 times brighter
40
What observational evidence supports the fact that our universe is expanding?
Red shift of galaxies
41
Where did the cosmic microwave background (CMB) come from?
Photons released when electrons and nuclei combined for the first time
42
Which of these is not considered to be evidence of the Big Bang theory?
The parallax angles to the farthest galaxies using the Hubble Space Telescope
43
The first elements, Hydrogen and Helium, were formed in what is known as the ____ with a ratio of ____.
Primordial Nucleosynthesis, 75% Hydrogen and 25% Helium
44
Ultimately, the fate of the universe will be determined by:
Gravity
45
After the Big Bang, in order for the universe to become transparent to photons, what had to happen?
the temperature of the universe had to col to ~3,000 K
46
The best scientific data and models suggest that the universe is
flat, expanding, and accelerating
47
If the universe has a positive curvature,
the universe is finite
48
What is the fate of the universe if ō > 1?
eventual collapse, hot
49
What is the fate of the universe if ō < 1?
expansion forever, cold