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The Universe Flashcards

1
Q

What is the closest star to earth besides our sun

A

Proxima centuri

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2
Q

Why is alpha centuri and proxima centuri confused

A

Because they are twin stars that orbit each other. Alpha is actually bigger then proxima. The light we from them mainly comes from alpha

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3
Q

How far is proxima centuri

A

4x10¹³ km away
4.2 ly

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4
Q

Why is km not the best measurement. What to use instead

A

The distance is to big and it’s hard to comprehend. Instead we use light years

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5
Q

What is a light year

A

The distance that light travells in 1 year

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6
Q

How fast does a light year travel

A

300,000km per second

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7
Q

What is another measurement. How many light years is it

A

Parsec (pc) 1 parsec is 3.26 light years

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8
Q

How convert light years to parsec

A

Distance in parsec = distance in light years ÷ 3.26

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9
Q

What is a parallax

A

A phenomenon that causes us to see the same object from slightly diffrent views when our viewing position changes

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10
Q

What is gravity what does it rely on

A

A very weak force that exists between two objects. Size of object and distance between their center of mass

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11
Q

What does nuclear fusion release

A

Huge amounts of heat and light energy, which is the source of energy for all stars

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12
Q

How do hydrogen atoms form larger helium atoms

A

Hydrogen (atomic number 1 ) is compressed under immense pressure and temperature caused by gravity to create helium (atomic number 2)

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13
Q

How is the excess amounts of energy released in radiation

A

Huge amounts of excess energy is released in the form of electromagnetic radiation

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14
Q

Electromagnetic radiation examples

A

Radio waves, microwaves, infared, visible light, UV, Xray and gamma rays

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15
Q

Constelations is what

A

A group of stars

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16
Q

What is a solar flare

A

Large explosions from the sun

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17
Q

What is a star

A

A giant sphere of extremely hot, luminous gas (mostly hydrogen and helium) held together by gravity

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18
Q

What is stellar evolution

A

Process of a star changing through time

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19
Q

Why does a bigger star live shorter

A

The hydrogen supply of a big star is used up quicker due to higher core temperatures. Other stars that burn longer because they tend to be colder

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20
Q

Info about low mass stars

A

Smallest, coldest and dimmest stars of all. Burn red, orange, or sometimes yellow due to low heat. Very long lives as they burn fuel extremely slowly 10-50 billion years.
E.g proxima centuri
No more than 0.5 solar masses

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21
Q

Medium star info

A

0.5- around 3 solar masses. Burn orange and yellow. Average life span is about 5-15 billion years. E.g our sun

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22
Q

High mass stars

A

Greater then 3 solar masses. Extremely hot and glow blue and white. Very short life spans couple billion to as low as 10 million years. End their lives with a supernova

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23
Q

How are stars formed

A

By gravitational collapse of dust and gas called Nebulae

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24
Q

What is a prostate the result of

A

The gravitational collapse of a nebula

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25
Qualities of a prostar
Not very dense, very large, spins very rapidly, usually lasts 100,000 years
26
Why is the result of the prostar rotating rapidly
Generates intense heat and pressure, thus causes gas cloud to collapse further
27
When is a star born
When the prostars temp reaches about 10 million degrees and hydrogen fusion occurs
28
What is the life cycle for low and medium mass stars
Turns to red giant, then into a planetary nebula, then white dwarf, then black dwarf
29
What does main sequence signify and how long of its life does it normally spend
Where it's core is capable of hydrogen fusion, 90% of a stars life is spent in this stage
30
Why do bigger stars exist the main sequence quicker
Because they burn and use up their hydrogen quicker then smaller stars
31
When does a star leave the main sequence
When a star has fused all the hydrogen in its core into helium
32
Life cycle of a highway mass/massive star
Turns to red super giant, then supernova, then a neutron star or black hole depending on the solar masses of its core
33
What happens to turn into a red giant
Fused all hydrogen and nuclear fusion stops, star collapses due to gravity, outer layers cool and reden, this can last billions of years
34
What happens if the red giant core continues to heat up to extreme temp, and what happens after, what does it leave behind
Helium fusion happens, once all helium is used up the star expels outer layer of gas in an explosion called a planetary nebula, leaving behind a white dwarf
35
What is a white dwarf made of, how does it generate alot of heat, how many solar masses can the star be
Up to 1.4 solar masses, made of mainly carbon, and oxygen, small size and high density causes extreme heat that turns it white
36
How are black dwarfs formed, what will eventually happen, are there any in the universe
None that we know of , remains of white dwarf formed due to gradually cooling and dimming as they burn their remaining fuel. Will keep burning until no longer visible to us
37
What can happen in a red supergiant, what can be formed
Core temps so high that nuclear fusion can occur even after helium is exhausted(meaning bigger elements can form) carries on until iron is formed
38
What happens when the core of a supergiant turns into iron
It has reached the end of its life and collapses instantly unde the enormous gravity of the core, it shrinks drastically in a matter of seconds, temp spikes and triggers and explosion called a supernova
39
What can happen in a supernova due to high energy
Insane amounts of energy released even iron can fused and all the elements higher than iron form
40
What is left after a supernova and what happens to it
Only the core is left, what happens depends on size. Heavier turns into a black hole, lighter turns into a neutron star
41
Neutron star qualities
1.4-3 solar masses, highly dense made of neutrons, densest and heaviest objecst in the universe
42
How are neutrons in a neutron star formed
By huge gravity squashing electrons with protons to form neutrons
43
Balck hole qualities
>3 solar masses, gravity force is so strong that collapse is unstoppable. Collapses to a point where not even light can escape scince gravity is so strong, gravity is so strong it can "eat" neighbouring stars and planets
44
Who proved the theory that the milkyway was made up of many stars
Galileo Galilei in the 17th century, by looking through the invention of the telescope
45
What kind of galaxy is the milky way
A spiral galaxy rotating around a black hole
46
Why xant galaxies be measured by parallax what are they measured in
To far away that a parallax cannot estimate how far away they are Instead Cepheid star is used
47
What do Cepheid stars cycle, what does the rate depend on. What tells us how far away it is
A consistent cycle from bright to dim at various rates. Rate depends on how bright the star is. The brightness determines the distance away
48
What is the steady state theory
Until 1970's it was thought that the universe was infinite and has always existed in roughly the same form observed as of today. Steady as you go nothing changes
49
Info on big bang theory, who found, how found, what found
Found by Edwin Hubble who worked out the universe was expanding. Showed us that the furthur the galaxy is away from us, the faster it is moving away. By using Cepheid stars to calculate distance away then used Doppler effect to calculate how fast they are travelling through space relative to us
50
What is the Doppler effect
Increase in pitch and volume as it comes towards you, decreasing pitch and volume as it goes away. The waves bunch up as they come towards us and stretches out as it goes away
51
The Doppler effect with light
When hydrogen fuses the star releases light, but the light must travel throught the stars atmosphere, so some light is absorbed by the hydrogen atoms so dark lines in the spectrum form. If light came from a stationary star that was burning hydrogen, he would know where in the colour spectrum the dark lines will be
52
What does the colour of the star depend of in terms of light Doppler
Whether the star is stationary. Quicker speed= higher frequency= more likely blue white colours If it's stationary, the black line is in the middle Slower speed and frequency pushes line out towards the reds and oranges
53
What does the colour of the star depend of
Whether the star is stationary. Quicker speed= higher frequency= more likely blue white colours If it's stationary, the black line is in the middle Slower speed and frequency pushes line out towards the reds and oranges
54
What is the single point which represents the beginning of the universe
The singularity
55
2 pieces of evidence for the big bang
The expansion of the universe and Hubble's red light shift Doppler effect Cosmic background microwave radiation
56
What is the high light energy called, where is it released, why si it released
Gamma rays, in the singularity( congregation of energy) it releases very short gamma rays Charged particles vibrating very quickly and produce extremely high energy electromagnetic radiation
57
What is the relationship between energy and matter
Energy is matter matter is energy
58
How does matter in stars turn into energy
The matter in the hydrogen atoms turn into energy
59
When did the universe start producing light
When gravity formed nebula then stars
60
Why where there no light in the dark ages
Because there was no matter in space to produce light until stars were formed

SCIENCE (7 decks)

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