Exam 3 Flashcards
1
Q
Because energy must be conserved, energy level transitions can only occur when?
A
When an electron gains or loses the specific amount of energy separating two levels.
1
Q
Don’t forget to do homework #6 and #7 on mastering and tutorial on page 71. LOTS of stuff.
A
1
Q
The larger the telescope, the better the?
A
Angular resolution.
1
Q
What is the primary device in a refracting telescope?
A
A lens
1
Q
Why put telescope’s in space?
A
Because they are above the earth’s atmosphere and free from daylight, turbulence, weather, and light pollution.
1
Q
A low-density cloud of gas emits light only at specific wavelengths that depend on its composition and color is called?
A
An emission line spectrum.
2
Q
Name at least 4 attributes that are best for ground-based telescopes.
A
Calm, high, dark, and dry.
2
Q
Do cold stars always appear to have a different (greater or fewer) number of lines in their absorption spectra than hot stars?
A
No.
2
Q
When stars fuse hydrogen into ___ they are on the ___ ____.
A
Helium. Main sequence.
2
Q
Name the two vertical axis on an HR diagram.
A
Luminosity and absolute magnitude.
3
Q
This is the simplest element.
A
Hydrogen.
4
Q
How bright a star appears depends on what?
A
How far away it is and how much light it releases according to the inverse square law.
4
Q
The horizontal axis of an HR diagram represents?
A
Surface temperature.
5
Q
Brighter objects have _____ magnitudes, and fainter objects have ____ magnitudes.
A
Lower, higher.
6
Q
Hot/dense energy sources viewed through thick gas appear in what type of spectra?
A
Absorption.
7
Q
The ___ is the visible layer of the sun.
A
Photosphere.
7
Q
When m = M, then the star is located exactly how far away?
A
10 parsecs.
8
Q
Visible surface of the sun.
A
Photosphere.
8
Q
These type of stars have the deepest balmer lines.
A
A.
9
Q
Place the following on either the upper right, lower right, lower left, or upper left quadrants of an HR diagram.
- Hot and bright
- Hot and dim
- Cool and bright
- Cool and dim
A
Hot and dim = lower left
Hot and bright = upper left
Cool and bright = upper right
Cool and dim = lower right
10
Q
The energy levels of electrons are quantized, and the study of this is what?
A
Quantam physics.
10
Q
We think that the corona gets its heat from the Sun’s?
A
Magnetic field.
11
Q
Mirrors are the primary optic in what type of telescope?
A
Reflecting.
11
Q
Middle layer of the solar atmoshpere.
A
Chromosphere.
12
Given the spectrum is VIBGYOR and two stars peak at the V side, which star appears red?
Neither
12
Electrons are ___ charged particles.
Negatively.
12
What are the two main types of telescopes?
Refracting and reflecting.
12
\_\_\_ numbers correspond to brighter stars
\_\_\_ numbers correspond to dimmer stars
Smaller/negative = brighter, larger/positive = dimmer.
13
The sun is what kind of star?
G2.
14
Refracting telescopes are short and narrow.
False, they must be long with large, heavy lenses.
15
The main properties of telescopes we are concerned with are?
Collecting area, angular resolution,
16
Without fusion, the star is no longer in ____ \_\_\_\_\_.
Hydrostatic equilibrium.
18
Hot/low density clouds of gas appear in what type of spectra?
Emission.
18
Suppose you want to determine the chemical composition of a distant planet or star. Which of the following will be most useful to have?
1. high spectral resolution
2. high angular resolution
3. high turbulence
4. a radio telescope
High spectral resolution
19
The primary mechanism of fusion in the sun is what?
Proton-proton
20
During the red giant phase when helium begins to fuse into carbon and oxygen, this is called what?
Triple-alpha process.
21
Spica is giving off 1000x more light (its luminosity is 1000X higher) than Rigel. So why is Spica dimmer as seen from Earth?
It has a larger distance.
21
The core left behind after a star dies is called a ___ \_\_\_\_.
White dwarf. (remember it's a peaceful death)
22
The star’s ____ determines the strength of its spectral lines.
Surface temperature.
22
These stars have molecular absorption lines.
M.
24
If an object moves 3 times farther away, it appears ___ dimmer.
9 times. (3 squared = 9)
25
A telescope's "light bucket" is its.
Light collecting area.
26
Will a star 10x mor massive than our sun live ten times longer, ten times less, or more than ten times less than the sun?
More than 10 times less.
27
Imagine that you observe the sun using a telescope in an orbit high above earth's atmosphere. Which spectra would you observe by analyzing sunlight?
Absorption.
29
Converting mass into energy.
Nuclear fusion.
30
What is the pulse surrounding a white dwarf called?
Planetary nebula.
32
M stars have ___ absorption lines by molecules, such as titanium oxide (TiO) - at higher temperatures.
Strong.
33
Absorption lines contain what?
Atoms moving their electrons to higher levels.
34
Which of the following statements best describes the two principle advantages of telescopes over eyes?
* Telescopes collect more light and are unaffected by twinkling.
* Telescopes can collect far more light with far better angular resolution.
* Telescopes can collect far more light with far greater magnification.
* Telescopes have much more magnification and better angular resolution.
Telescopes can collect far more light with far better angular resolution.
34
O stars have ___ hydrogen lines, because at those high temperatures, the hydrogen at the surface is ionized, and thus cannot absorb photons.
Weak.
35
Which are the hottest stars? The coolest?
O are hottest, M are coolest. Remember OBAFGKM.
37
All stars produce a what?
Absorption line spectra.
38
Name the three layers of the sun's atmoshpere.
Photosphere, chromosphere, and corona.
39
Elements are atoms with different numbers of what?
Protons.
40
If you try and give an electron at level one 5eV of energy, what would happen?
It would not accept it because it is not enough energy to reach level two. It requires 10.2 eV.
41
The possible energies are known as the ___ \_\_\_\_ of an atom.
Energy levels.
43
The apparent magnitudes of two stars, Rigel and Spica: Rigel: m = -0.01 and Spica: m = 1.00. Which looks brighter from Earth?
Rigel.
44
Electrons always want to be a what state?
Ground.
44
Most of the sun's x-rays come from?
The corona.
45
Hot/dense energy sources appear in what type of spectra?
Continuous.
47
The nucleus of an atom contains what two particles?
Protons and neutrons.
47
Stars in the upper right of an HR diagram?
Supergiants.
48
Define apparent magnitude.
How bright stars appear from earth.
50
All ordinary matter is made up of?
Atoms
50
Which telescope is most like the human eye?
Refracting.
51
A cloud of gas between a light source and the viewer will absorb most of the light at specific wavelengths thus we see?
An absorption line spectrum.
52
Protons are ____ charged particles.
Positively.
54
What are two things we can learn about stars by studying their light?
Temperature and chemical composition.
56
Which of the following wavelength regions can be studied with telescopes on the ground?
* infrared, visible, and ultraviolet light
* radio, visible, and very limited portions of the infrared and ultraviolet regions
* all light with wavelengths shorter than infrared wavelengths
* all light with wavelengths longer than ultraviolet wavelengths
Radio, visible, and very limited portions of the infrared and ultraviolet regions
58
The magnitude system is backwards.
True. We would assume a higher number means brighter but it's the opposite.
60
Elements with different types of neutrons are called what?
Isotopes.
62
Stars of the same absolute magnitude number have the same?
Luminosity.
63
Which type of telescope is larger in diameter?
Reflecting.
63
The measure of total energy output by the sun is?
Luminosity.
64
The sun is in what state? (which is why gravity isn't collapsing it)
Hydrostatic equilibrium.
66
Name the three layers of the sun's interior.
Core, radiative zone, and convective zone.
67
Energy generated by the sun's core propogates to the surface very rapidly.
False, this process takes tens of thousands of years.
68
What are the basic steps of the proton-proton chain?
1. two protons fuse to make deuterium nucleus.
2. the new nucleus and a proton fuse to make a new nucleus of helium-3
3. two helium-3 nuclei fuse to form helium-4 releasing two excess proton
69
Low mass stars have less than __ times that of the sun while high mass stars have more than ___ times the sun.
Eight.
70
White dwarfs have very little mass.
False! They have way more mass.
72
What three layers of the sun can be viewed with a telescope?
Photosphere, corona, and chromosphere.
73
What phenomenon causes ground-based telescopes to render images of stars that appear to twinkle?
Turbulent air flow.
74
Emission line spectrum contains what?
Atoms moving their electrons to lower levels.
76
Nuclear fusion takes place at the __ layer of the sun.
Core.
77
Red giants are a result of what phenomenon?
Shell burning.
78
Atoms are composed of what three particles?
Protons, Neutrons, and Electrons.
79
The sun is made up primarily of what element?
Hydrogen.
80
When the carbon core shrinks and has a helium and hydrogen burning shell on the outside, it's called what?
Double shell burning.
82
For each of the following star descriptions, state whether the star would be a red giant, white dwarf, or main sequence star.
a) very bright (high luminosity) and very hot (high temperature)
b) very dim and cool
c) very dim and very hot
d) very bright and cool
a) Main sequence
b) main sequence
c) white dwarfs
d) giants and red giants
83
What does angular resolution measure?
The angular size of the smallest features that a telescope can see.
84
Energy transported upwards by photons occurs in the __ layer of the sun.
Radiation.
85
The circles in the diagram above represent energy levels in an atom, and the arrows show electron (blue dot) transitions from one energy level to another. (The spacing between circles represents differences in energy: A larger spacing means a greater difference in energy.) Assuming that the transitions occur as photons are emitted, are these ranked appropriately?
Yes
86
A ___ \_\_\_\_ is a label given to a star based on the absorption lines in its spectrum, which depend on the ____ \_\_\_\_\_.
Spectral type. Surface temperature.
87
Without hydrostatic equilibrium a star starts to?
Collapse.
88
Fission means to ....
Split an atomic nucleus.
89
Which spectral type of start is hottest? Coolest?
O hottest, M coolest.
90
What device separates different wavelengths of light in a telescope before they hit the detector?
Spectrograph.
90
Stars on the main sequence form a correlation in a plot of ____ \_\_\_\_ versus \_\_\_\_.
Surface temperature. Luminosity.
92
Is there a relationship between luminosity and surface temperature?
Yes.
93
The smallest angular size we can distinguish.
Angular resolution.
94
Photons are absorbed by atoms when an electron moves from a ___ energy level to a ____ energy level.
Low to high.
96
Which star would appear brighter? A star with a magnitude of -1.4 or a star with a magnitude of -4.4?
The star with a magnitude of -4.4.
98
Study the HR diagrams - no question.
99
What are energy level transitions?
When an electron can rise to a higher energy level or fall to a lower energy level.
100
Photons are emitted from an atom when an electron moves from a ___ energy level to a ____ energy leve.
Higher, Lower.
101
Stars of the same spectral type have the same?
Temperature.
102
Which element will not be made in the sun?
1. Helium
2. Carbon
3. Oxygen
4. Iron
4. Iron
104
1 over distance square is proportional to what?
The apparent brightness of an object.
106
What force hold protons and neutrons together?
Nuclear.
107
The vertical axis of an HR diagram represents?
Stellar luminosity?
108
A first magnitude star is ____ than a sixth magnitude star.
Brighter.
109
What is used in astronomical images to represent energy?
Color.
110
When m\>M, then the star appears dimmer than it would if it were 10 pc away so it must be ___ than 10 parsecs.
Farther.
111
Stars in the lower left of an HR diagram?
White dwarfs.
112
Where would these type of stars appear on an HR diagram?
1. White dwarfs
2. Giants/Super Giants
White dwarfs are found on lower left. Giants/Super Giants found on upper right.
113
The higher a telescope's ___ the better detail we see.
Spectral resolution.
114
What is absolute magnitude?
The apparent magnitude of a star if it were 10 parsecs away from earth.
115
Neutron particles are ____ charged.
Neutrally.
116
Most stars fall into the ___ \_\_\_\_ of an HR diagram.
Main sequence.
117
The sun has enough energy to burn for approximately how many more years?
Five billion.
118
Imagine that you observe a star to have an apparent magnitude of 0.2, and you know that it is 100 parsecs away from us. What is the likely absolute magnitude?
A) -4.8
B) 0.1
C) 0.2
D) 5.2
A) -4.8
120
When a rainbow of light spans a broad range of wavelengths without interruption, it's called a?
Continuous spectrum.
121
Luminosity is also known as?
Intrinsic brightness.
122
Compare some stars:
Absolute | Apparent
MSun = 4.8 | mSun = -26
MSirius = 1.4 | mSirius = -1.46
MBetelgeuse = -5.6 | mBetelgeuse = 0.50
Which star is the most luminous?
Which star looks brightest from Earth?
Sun appears brighter. Betelgeuse most luminous.
123
What two types of waves easily pass through earth's atmosphere?
Radio and visible light.
124
What is the correct order for spectral types?
O B A F G K M
Oh Be A Fine Girl Kiss Me
126
Continuous light specturm includes light from what?
Blackbody
127
What are the three types of spectrum we studied in class?
Continuous, emission, and absorption.
128
Energy transported by rising hot gas occurs in the ___ zone of the sun.
Convection.
130
Nuclear fusion in the Sun’s core turns four hydrogen atoms into one helium atom. Which of the following is true?
A) The mass of the helium atom is equal to the mass of the four hydrogen atoms.
B) The mass of the helium atom is less than the mass of the four hydrogen atoms.
C) The mass of the helium atom is greater than the mass of the four hydrogen atoms.
B) The mass of the helium atom is less than the mass of the four hydrogen atoms.
131
If a mirror doubles in size, the collecting area increase by what?
Four times.
132
High mass stars live longer and burn slower than low mass stars.
False. Greater mass = more pressure = more fusion = higher fusion rate = shorter life
133
Name the two horizontal axis of an HR diagram.
Surface temperature and spectral type.
134
Define spectroscopy.
The process of obtaining a spectrum and reading the information it contains.
135
Do cold stars always appear to have more lines at either the blue or red ends of their absorption spectra than hot stars?
No.
136
Which of the following lists the stages of life for a low-mass star in the correct order?
1. main-sequence star, white dwarf, red giant, planetary nebula, protostar
2. protostar, main-sequence star, planetary nebula, red giant
3. protostar, main-sequence star, red giant, planetary nebula, white dwarf
4. protostar, main-sequence star, red giant, supernova, neutron star
3.) protostar, main-sequence star, red giant, planetary nebula, white dwarf
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