Everything Stars Flashcards
1
Q
What are safe methods to observe the Sun?
A
Pinhole Projection:
Sunlight passes through a pinhole lense into the opposite wall.
Telescopic Projection:
A telescope with a sun shade is pointed at the sun, the light through the telescope is then projected by it onto paper. (sun shade, shades the paper allowing for the sun to be shown)
2
Q
What is a H-Alpha Filter?
A
A filter used in solar observation.
It only allows a wavelength of 656nm through (n=3 to n=2)
3
Q
Why is a H-Alpha Filter useful?
A
It produces contrast on the Sun’s Surface.
Allowing for better viewing for features, such as Solar Falres, Sunspots,Chromosphere and prominences.
4
Q
What is a Sunspot?
A
Cooler (∴ darker) regions on the Photosphere, where the convection currents are inhibited by strong localised magnetic fields.
5
Q
what is the coolest part of the Sun?
A
Sunspots
6
Q
What Temperature are Sunspots?
A
Umbra (darker central): 3500K
Penumbra (surrounds umbra): 4500K
7
Q
Why are Sunspots in Pairs?
A
North and South polarity
8
Q
How big are Sunspots?
A
1000km - 12000km
9
Q
What is the Sun’s Rotaional period?
A
Equator: 25 days
Poles: 36 days
10
Q
How can the Sun’s Rotational Period be measured?
A
The distance a Sunspot will move across the sun in a certain period of time is used
11
Q
Why does the Sun’s Rotaional Period differ across Latitudes?
A
Because the Sun acts as a fluid
12
Q
How long is a Solar Cycle?
A
11 years
13
Q
What is a Solar Cycle?
A
The time taken for Sunspot sto travel form the poles to the equator
14
Q
What is a Butterfly Diagram and what is it used for?
A
It shows the positioning of Sunspots and can be used to determine the length of the Solar Cycle
15
Q
Where are Sunspot located?
A
On the Photophere.
Few Sunspots above 40°N/S
Sunspots increase as latitude decreases
Few Sunspots below 10°N/S
16
Q
What happens to Sunspots over the Solar Cycle?
A
They move closer to the equator
17
Q
What is the Diameter of the Sun?
A
1.4 million km
18
Q
How far is Earth form the Sun?
A
150 million km
1 AU
19
Q
What is the composition of the Sun?
A
71% H
27% He
2% Other
(asthe sun is 99% mass of solar system this is also the composition of the solar system)
20
Q
What are the layers of the Sun?
A
Core: 15 million K Radiation Zone: 7-2 million K Convection Zone: 2 million - 5800 K Photosphere: 5800 K Chromosphere: 4500 K Corona: 2 million K
21
Q
Why is the Corona so hot?
A
Temperature is average kinetic energy of particle, as there are few particle they are able to move very fast
22
Q
Where on the Sun are X rays emited?
A
Corona and Magnetic loops.
As they require very high energies.
23
Q
What is the Proton-Proton Chain?
A
A nuclear fusion chain reaction, which occurs in the core of the Sun
4 protons → Helium-4 nucleus
24
Q
What is the Solar Wind?
A
A steady stream of charged particles (p, e-, α and ions), flowing outwards in all directions from the Sun’s corona
25
What are the energy range and speed of the Solar Wind?
0.5 - 10 keV
| 400 km/s (4 x 10^5)
26
What is Heliopause?
The point at which the solar wind is no longer strong enough to push away form the Sun.
Often considered the edge of the solar system.
27
What is the Van Allen Belts?
They are regions within the Earth's magnetic field where where charged particles can become trapped
28
Where are the Van Allen Belts?
Magnetosphere
Inner belt: 1.5 Earth radii
Outer belt: 5 Earth radii
29
What are the effects of the Solar Wind?
Aurorae
Geomagnetic Field
Cometary Tails
Ionising space mission
30
What causes the Aurorae?
Overflow of the Van Allen Belts.
High energy electrons can enter the atmsophere at high latitudes causing excitation and de-excitation of upper atmosphere (100km up)
31
When are Aurorae at their greatest?
Solar Maxima
32
How do Geomagnetic storms effect Earth?
Can effect radio comunication
| effect the transmission of power through power lines
33
What causes Geomagnetic Storms?
Coronal Mass Ejections
34
What causes a Comets Tail?
The Solar wind ionises and creates a ion/gas tail pointing away form the sun
35
What is the Bayer System?
The system used for denotaing the brightness of stars within a constellation.
eg. Alpha Orionis is Betelgeuse and Beta Orionis is Rigel
36
What is the Intensity of Light Proportional to?
1/r²
37
What is Apparent Magnitude?
The logarithmic scale for the brightness of astronomical objects, as they appear from earth.
Where the lower the number the brighter it is.
38
What are range of Apparent Magnitude?
```
Quasar: +26
Limit of bino/telescope: +10
Limit of naked eye: +5
Bright stars: 0
Bright Planet: -2
Moon: -11
Sun: -26
```
39
What is the base of the Apparent Magnitude scale?
100^0.2 ≈ 2.51
40
What are the differences in Magnitude?
```
Δ1 = x 2.51 = 100^(1/5)
Δ2 = x 6.31 = 100^(2/5)
Δ3 = x 15.85 = 100^(3/5)
Δ4 = x 39.81 = 100^(4/5)
Δ5 = 100 = 100^5/5)
```
41
What are examples for the brightness of stars?
0. 0 = α Lyra (Vega)
1. 1 = β Gemini (Pollux)
2. 0 = α Ursa Minor (Polaris)
3. 0 = γ Ursa Minor (Pherkad)
42
What is Absolute Magnitude?
The apparent magnitude a star would have if located at a distance of 10 parsecs
43
What is the equation for Absolute Magnitude?
```
M = m+5-5log(d)
M = Absolute Magnitife
m = Apparent Magnitude
d = Distance to object (in Parsecs)
```
44
What is the range of Absolute Magnitude?
-10 to +15
| Lower the number the brighter the object
45
What is the Sun's Absolute Magnitude?
+5
46
What is a Black Body?
An object that can absorb and emit radiation of all wavelengths
47
What happens if the Temperature of a Black Body is increased?
The range of emited wavelengths increases (greater range of photon energy).
The Peak Wavelength decreases (Wien's Law)
The Power output increases (Stefan's Law)
48
What is the Peak Wavelength?
λmax
| The Wavelength at which the intesity of light is a maximum
49
What is an example of a Black Body?
Stars
| As they emit and absorb all wavelengths
50
What is a Planck Curve?
It's the graph that shows the Wavelength and intensity of radiation from a star
51
What happens to a Planck curve if the temperature increases or decreases?
Increase: Peak (λmax) shifts left as higher frequency means lower wavelength. And Peak increases in height.
Decrease: Peak Shifts right and down
52
What is Wien's Law?
λmax ∝ 1/T
λmax x T = Constant
Wien's Constant = 0.00290
53
What is Stefan's Law?
```
P = σAT^4
P = Power
σ = Stefans constant = 5.67 x 10^8
A = Surface area of black body
T = Temperature
```
54
What is Stellar Spectroscopy?
A system where light form a star is passed through a diffractio grating to detect absorption lines.
55
Why is Stellar Spectroscopy used?
It shows what elements or molecules are in a star.
It finds the radial velocity of the star.
It finds the Surface temperature of the star
It finds the Magnetic field strength of the star
56
What order are Star classified in?
O: 50-25 x10^3 K Blue, He is prominent
B: 25-11 x10^3 K Blue/White, H is prominent
A: 11-7.5 x10^3 K White, H is prominent
F: 7.5-6 x10^3 K White/Green, Metals are prominent
G: 6-5 x10^3 K Yellow, Metals are prominent
K 5-3.5 x10^3 K Orange, Metals are prominent
M: <3.5 x10^3 K Red, Molecules (eg TiO) is prominent
57
What is the Sub categories of Star classification?
```
0-9
0 is hottest
9 is coldest
eg. F9 is hotter than G0
but F9 is colder than F8
```
58
What calssification is the Sun?
G2
59
Why has Star classification uneven ranges?
To offer greater resolution as most stars are between A and K
60
What is the Hertzsprung-Russel Diagram?
A graph showing the tempertaure and absolute magnitude of stars?
61
What shape is a Hertzsprung-Russel Diagram?
Go Look for one
62
What can be calculated from a Hertzsprung-Russel Diagram?
The distance to a star. Using its temperature/classification and its apparent magnitude.
As Absolute Magnitude can be estimated from the graph. then put in to M = m+5-5log(d).
63
What is Intensity proportional to?
I ∝ 1/r²
| Intensity ∝ 1/distance²
64
What is a Lightyear?
The distance which light travels in 1 year
| 9.46 x 10^15 m
65
What is a Parsec?
The distance at which a star will give a parallax angle of 1 arc second.
66
How is Parallax measured?
The angle which a star appears to move compared to distant background stars.
Measure from either side of the Earths orbit around the Sun.
Paralax is measure using a right angle triangle with the sun
67
What equation links Parallax and Discance?
Distance (pc) = 1/ Parallax (")
68
What is a Cepheid Variable?
A type of star with variable apparent magnitude.
They are used as Standard candles
Named after the first discovered Delta Cepheus
69
What is a Standard Candle?
An object with a known absolute magnitude.
eg:
Type 1a Supernovae, absolute magnitude of -19.5.
70
Why do Celpheid Varibles change in apparent magnitude?
Because they pulsate about an equilibrium.
1) Grav pulls in, increaseing temp ∴ more fusion ∴ more radiation pressure.
2) Star expands, pressure decreases ∴ temp decreases ∴ fusion slows.
3) Grav pulls in
71
How do you measure the distance to a Cephied Variable?
Measure its period, which allows for the calculation of absolute magnitude.
Calculate distance from average apparent magnitude and absloute magnitude.
72
What is the equation for the Absolute Magnitude of Cephied Variables?
```
M = -2.81 log(T) -1.43
M = Absolute Magnitude
T = Period of star in days (sometimes π rather than T)
```
73
What are Binary Stars?
Two stars that are Gravitiationaly Bound to each other and orbiting a common centre.
74
What is an Opitcal double?
Stars that look close to gether due to the perspective.
| One is far beyond the other.
75
What is the shape of the graph for the Intensity of an Eclipsing Binary?
The intensity has dips when the stars are behind each other.
76
What do Large and small dips mean in an Intensity-Time graph?
Large dip: Faint in front of bright
| Small dip: Bright in front of faint
77
What does it mean for Eclipsing Binary stars if the dips are all equal size?
The stars are the same intensity
78
What parts of the EM Spectrum reach the Earth's surface?
Visable
Radio
Microwaves
Small sections of the InfraRed
79
What is the best location for Telescopes?
```
Gamma: Space
X-ray: Space
UV: Space
Visable: Ground and Space
IR: Ground (at high altitudes) and Space
Microwave: Ground
Radio: Ground
```
80
What absorbs the EM in the Atmosphere?
```
Gamma: O2, N2 and Excited Nuclei
X-ray: O2, N2, Atoms and Molecules
UV: O3
Visable: H2O (Clouds)
IR: H2O (Clouds)
Microwave: H2O and O2 for short λ
Radio: e- for long λ
```
81
What does a shorter Wavelength require from a Telescope?
A more accurate/smoother Surface.
82
What is the Rayleigh Criterion?
Two Stars cannot be resolved if θ > λ/D
θ = Angular Seperation / Radians
λ = Wavelength / m
D = Diameter of the objective(mirror) / m
83
What does the Rayleigh Criterion mean?
A Larger wavelength requires a larger mirror to be able to resolve well.
84
What is a Radio Interferometer?
AKA: Aperture Synthesis Arrays
| The use of multiple telescopes operating together to increase resolution.
85
What is the Effective Resolution of a Radio Interferometer?
The Base Line of the Array
| the distance between the telescope
86
What was discovered using Radio Telescopes?
Quasars: Identified in the visable using the occulation of the moon, as it showed where it was based on where the radio stopped.
Jets from Black Holes: Above and Below the plane at which matter enters the hole.
Structure of the Milky Way: 21cm wavelength can penetrate stellar gas and dust.
Neutrons Stars: Beams are Radio waves.
87
What are the Advantages of a Space Telescope?
It's above the atmosphere: no refraction or scattering.
All wavelengths can be observed: no atmosphere to absorb wavelengths.
Can see the entire celestial sphere: due to the orbit shape and period.
88
What are Disadvantages to Space Telescope?
Expensive to develop, construct and launch.
| Hard/impossible to upgrade or fix the hardware. (software is sometimes upgradable).
89
What is the Power of a Telescope proportional to?
Power ∝ Diameter²
| as area is roughly diameter²
90
What is the Structure of Telescopes?
Gamma and X-ray: Series of mirrors slightly reflect the light closer and closer to focus
UV, IR and Visable: Mirrors reflect the light
Radio: Large reflecting dish
91
What are discoveries of IR Telescopes?
Planetary discs
| Nebula / Star formation
92
What are the 4 types of Nebulae?
Absorption Nebulae
Emission Nebulae
Planetary Nebulae
SuperNovae Remnants
93
What is an Absorption Nebula?
A Nebula which contains no stars, and is just a cloud of gas and dust.
They are creation nebulae as there dust and gas can form new stars.
They are observed as a silhouette.
94
What is an Emission Nebula?
A creation nebula which contains newly formed stars.
| They emit light as H and O atoms within the gas and dust are excited.
95
What is a Planetary Nebula?
It is the end state of a low mass star.
The radiation pressure within the star is stronger than gravity, causing the layers to be blown into space.
They are symetrical and form shapes such as rings and hourglasses.
They have a white dwarf at the centre.
96
What is a Supernova Remnant?
The end state of a high mass star.
They look like an explosion.
Containing a Black hole or Neutron star
97
What is an Open Cluster?
An irregular shaped clump of 100's of stars.
The stars within are young, hot and recently formed.
They are within the Milky Way.
98
What is a Globular Cluster?
Regular spherical shaped clump of 10000's of stars.
The stars are often about 10 billion years old.
There are 150 with the Milky Way.
They form a "Halo" around the Galaxy
99
What is the Evolutionary proccess for a Low Mass Star?
Absorption and Emmision Nebula
Main Sequence (or brown dwarf if < 0.1 solar masses)
Red Giant
White Dwarf
100
What does a Stars Evolutionary path depend on?
Its Mass
101
What happens in the Nebula Phase of Star Evolution?
Gravitaional and Ekectrostatic forces make H clouds collapse in to hot dense pockets.
These can then begin fusion.
102
What is a Brown Dwarf?
A Stellar body which wasn't big enough to begin fusion.
| look like jupiter
103
What happens in the Main Sequence?
Hydrostatic Equilibrium between the gravitaional forces and raditaion pressure, keep the amount of fusion stable.
104
What happens if Gravity is stronger than the Radiation Pressure?
The star will collapse, raising the core tempertaure increasing the rate of fusion. Thus increasing the radiation pressure.
105
What is Radiation Pressure?
It is the outwards pressure applied by the photons being emited by the fusion in a stars core.
It counter acts the inwards force of gravity and maintains the stars size.
106
Do High or Low mass stars have a faster rate of fusion.
High mass stars have a higher rate of fusion, due to the higher temperature caused by a higher pressure createde by gravity.
107
What is considered a high or low mass star?
Low Mass is less than 8 solar masses
| High mass is greater than 8 solar masses
108
What is the Triple Alpha Process?
The fusion process from three α particles to a Carbon nuclei.
109
What causes a star to become a Red Giant?
When a reduction of nuclear fusion (producing H) in the core occurs. There is a reduction in Radiation Pressure, causing Gravitaional Collapse. This increases pressure and temperature causing fusion of heavier nuclei.
110
What happens if the Radiation Pressure from fusion of heavier elements is greater than gravity?
The layers of the star will be ripped away fomring a planetary nebula
111
What is the Chandrasekhar Limit.
The theoretical mass limit of a stars core as to whether it will become a supernova or planetary nebula.
≈ 1.4 solar masses
112
What is a White Dwarf?
Stars balenced due to gravitational collapse and electron degeneracy pressure.
113
What balances a Main Sequence Star?
Gravitational Collapse and Radiation Pressure
114
What balences a White Dwarf?
Gravitational Collapse and Electron Degeneracy Pressure.
115
What is Electron Degeneracy Pressure?
The Due to the Pauli Exclusion Principle, whereby no two electrons can exist in the same state (thus they cannot exist in the same energy level at the same time.
116
What is the Evolutionary Process of a High mass star?
```
Absorption and Emission Nebula
Main Sequence
Red Supergiant
Supernova
Neutron Star (lower mass) or Black Hole (higher mass)
```
117
What is a Red Supergiant?
A very large star formed by the depletion of H in the core and subsequent fusing of heavier nuclei.
118
What causes a Main Sequence star to become a Red Supergiant?
The depletion of H in the core, causing less fusion, causing less radiation pressure, causing a gravitaional collapse. The collapse causes a increase in pressure and temp causing a layer in the core to form of the fusing of heavier elements, this happens repeatedly up to Fe 56.
119
Why can stars not fuse heavier elements than Iron 56?
Iron 56 is the most stable nuclei. Therefore less energy is released than put into the fusion of a heavier nuclei.
120
What is the Power output of an A1 Supernova?
M = -19.5
≈10^10 Suns (the same brightness as a galaxy)
≈ 10^44 J (total energy output of the sun over its entire life)
121
How can the distance to an A1 Supernova be measured?
As they are standard candles their Absolute Magnitude is always -19.5, when its Apparent Magnitude is measured they can be put into the equation.
M = m + 5 - 5log(d)
122
What is a Neutron Star?
A Star composed entirely of Neutrons
123
What causes a Neutron star?
The gravitaional collapse of a Red Supergiant (if below a certain size) will collapse with such pressure it will force the electrons in the atoms into the nuclei causing Electron Capture.
124
What balences a Neutron Star?
Gravity and Neutron Degeneracy Pressure.
125
What Properties does a Neutron star have?
≈ 10km diameter (the red supergiant could reach past neptune).
Made of Neutrons
Very High density (≈240 million tonnes per cm^3)
Very High g field near the surface
Rotates very fast (100-1000Hz)
Very strong magnetic field
Emits an narrow beam of Radiowaves
126
Roughly how big is a Red Supergiant?
It could reach neptune if at the centre of the solar system.
127
What is the Observational evidence for Neutron Stars?
Radio Telescopes observe the pusling due to the rotaion and emission of lots of radiowaves.
128
What are Neutron stars sometimes known as?
Pulsars
129
What Properties does a Black Hole poccess?
Very Very large g field near to surface.
Very Very large Density (infinite?)
Very small radius (Zero? as cannot see past Swarzchild)
Most are several solar masses.
130
What are the requirement for the formation of a Neutron star?
The neutron star must be at least 3 solar masses
131
What is a Swarzchild Radius?
The Event Horizon.
| The distance from the centre of the hole at which the escape velocity is the speed of light
132
`What evidence is there for a Swarzchild Radius?
The frequency emitted by the accretion disc increases to X-rays. As it gets hotter due to the increased velocity
133
How do Low mass stars move on the H-R Diagram?
Main sequence → Red giant → White dwarf
134
How do High mass stars move on the H-R Diagram?
Main sequence → Red supergiant
135
Why are Neutron stars and Black Holes not on the H-R Diagram?
Because they do not emit visable wavelengths.
136
What is Observational Evidence for Black Holes?
The emission of X-rays due to the accretion disc and it behaving as an eclipsing Binary around its partener star.
137
What is the Distance between Earth and the centre of the Milky Way?
≈ 10000pc
138
What is the Diameter of the Milky Way?
≈30000pc
139
What is the Milky Way?
A band of light across the sky whcih binoculars can resolve into thousands of stars.
This is the plane of our Galaxy
140
What shape is the Milky Way?
From the side it appears as a flat disc with a bulge above and below the middle.
From above it appears as a Barred Sprial galaxy
141
How thick is the Central Bulge of the Milky Way?
≈6000pc
142
What is the 21cm Line?
It is the wavelength of Atomic Hydrogen.
It is a frequency which can penetrate intersellar dust and the earths atmosphere. Allowing for the galaxy to be obseved despite many wavelengths being blocked.
143
What was discovered using the 21cm Line?
The rotaional velocity of the Milky Way/
144
What is the Local Group?
≈ 30 of the closest galaxies of which the Milky Way is part of.
145
What are examples of objects in the Local Group?
Large Magellanic Cloud
Small Magellanic Cloud
Andromeda (M31)
Triangulum (M33)
146
What is the Virgo Cluster?
It is the Cluster which the Local Group is part of.
| It consists of about 3000 galaxies and is roughly centred on the elliptical galaxy Virgo (M87). It is about 33Mpc across
147
What is the Hydra-Centaurus Supercluster?
It is the Supercluster to which the Vigro cluster belongs.
148
What are the five types of Galaxy?
```
S Spiral
SB Barred Spiral
E Elliptical
I Irregular
S0 Lenticular
```
149
What is a Spiral Galaxy?
It has a flattened Disc conatining Star formation and a central bulge.
150
What is a Barred Spiral Galaxy?
It has a Central bar through the nucleus from which the arms emerge perpendicular to.
151
What are the sub-categories of S and SB Galaxies?
a: has the most prominent nucleus and has tight arms.
b: It is inbetween a and c
c: has a small nucleus and open spiral arms.
152
What is a Elliptical Galaxy?
Symetrical dense clouds of stars and gas which increase with brightness at the centre.
E0: Spherical
E7: Highly Elliptical
153
What is an Irregular Galaxy?
A Galaxy with no shape or structure.
| They are generally quite small.
154
What is a Lenticular Galaxy?
A class between Elliptical and Spiral
155
What type of Galaxy is the Milky Way?
SBb
156
What is Hubble's Tuning Fork Diagram?
```
A model for Galactic evolution by Edwin Hubble.
It has all galaxies starting as Elliptical then splitting to either Spiral or Barred Spiral.
With "a" sub class being befor "c"
```
157
What is an Active Galactic Nucleus?
A galaxy which emits X-rays and Radio waves from its nucleus.
158
What is a Radio Galaxy?
A primarily elliptical galaxy which emits 10^6 more energy than a normal galaxy.
The radio emissions produce two large lobes either side of the galaxy.
159
What is a Seyfert Galaxy?
A very bright, compact sprial galaxy which emits strong and variable IR and X-rays.
160
What is a Quasar?
A very optically faint galaxy which emits a huge amount of X-rays. which have been massivly red shifted.
They are very far away and thus very old.
161
What is a Blazer?
A quasar like object that is much closer, thus less red shifted.
Emit strongly in whole EM spectrum.
They have varying bightness generally with T ≈ 1 or 2 days.
162
What is Cosmology?
The Study of the large scale structure of the Universe.
| Its past, present and future.
163
What is the Doppler Effect?
The apparent change in Wavelength(∴ frequency) of a source due to its relative radial motion with respect to the observer.
164
What is the equation for Doppler Shift?
```
Δλ/λ = v/c = Z
Δλ = Differnce between actual and observed wavelength.
λ = Actual Wavelength
v = Radial velocity of source
c = Speed of light
Z = Doppler shift
```
165
What does a Blue Shift mean?
The frequency is increasing (∴ wavelength decrease).
| It means the emitter is moving towards the observer.
166
What does a Red Shift mean?
The frequency is decreasing(∴ wavelength increasing).
| It means the emitter is moving away from the observer.
167
What are uses of the Doppler Effect?
To calculate the relative radial motion of an object.
| To identify unresolvable spectroscopic binary systems.
168
What is Hubble's Law?
Except for a few nearby galaxies, the speed at which a galaxy is receding from us is proportional to its distance from us.
169
What is assumed by Hubble's Law?
We are NOT the centre of the universe. All objects are moving away from each other.
The universe is not expanding quicker at the edge.
The universe has no edge.
The universe is expanding uniformly.
170
What is the equation for Hubble's Law?
v =H(0) x d
v = Recession Velocity / km s^-1
H(0) = Hubble Constant (68 km s^-1 Mpc^-1)
d = Distance to galaxy / Mpc
171
What can be used to identify the distance to a galaxy for Hubble's Law?
1a Supernovae
| Hubble originally used the anglular width if the galaxy using the priciple that small galaxies are far away
172
What are the Cosmological Models created by Hubble's Law?
The Big Bang
The Steady State Theory
The Cyclic Universe
173
What is evidence for The Big Bang?
Cosmic Microwave Background Radiation
Quasars
Relative Abundence of Elements
174
How can the age of the Universe be calculated?
Age = 1 / Hubble Constant
| Assuming the universe has been expanding at a constant rate.
175
Why is CMB Radiation evidence against Steady State?
After the big bang and before recombination the universe was plasma and EM can't pass through it. During the recombination epoch atoms formed and space became "transparent". CMB is Gamma photons that were from this tiem and have been red shifted since.
176
What is the CMB Radiation?
A constant uniform signal from all directions at all times.
| With a wavelength of 1.07mm.
177
What is the Temperature of Space using CMB?
Wien's Law using CMB wavelength of 1.07mm
λ(max) x Temp = 0.00290
T = 0.00290 / λ(max) = 0.00290 / 0.00107
T = 2.71 K
178
How are Quasars evidence against the Steady State Theory?
They are massively Red shifted (second to only CMB).
Therefore they are far away, thus long ago.
Showing the universe has changed.
179
Is there evidence for The Big Bang?
Not really.
| Only evidence against other theories (eg steady state)
180
What is Dark Matter?
Matter which constitutes about 25% of the universe, and 80-90 % of the Galaxy. Theories include Neutrinos and WIMPs (weakly interacting massive particles).
181
Where in the Galaxy is Dark Matter located?
Around the edge of the Spiral Arms.
182
What evidence is there for Dark Matter?
Spiral arms of galaxies.
They spin with a constant angular velocity, which is only possible if the majority of mass is outside the arms.
With out this the arms would have different angular velocity along them (due to circular motion) and would be pulled apart.
183
How does Dark Matter and Dark Energy relate?
They don't.
| They are both dark because it can't be seen, understood or identified.
184
What evidence is there for Dark Energy?
The rate of expansion of the universe is increasing.
| Creating the complication that there is a repulsive force opposing gravity. Which was thought to be slowing expansion.
185
What is the Composition of the Universe?
5% Baryonic Matter
25% Dark Matter
70% Dark Energy
186
What is the Big Crunch?
The theoretical end of the universe from the slowing of expansion. and collapse due to gravity.
187
What is Big Freeze or Heat Death?
The continued expansion would cause temperature to asymptotically approach 0k.
Matter and energy would be so spread out that no stars could form.
188
What is the Big Rip?
The density of Dark energy increases with time causing greater acceleration of universe expansion. Hubble constant increases.
All forms of matter disintergrate into unbound elementary particles and EM.
