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life science > Birth, Life And Death Of Stars > Flashcards

Birth, Life And Death Of Stars Flashcards

1
Q

What are Stars born in?

A

Stars are born in vast, slowly rotating, clouds of cold gas and dust called nebulae

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2
Q

What are the masses of these nebulae

A

Between 100 thousand and 2 million times the mass of the sun

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3
Q

What are the diameters of these nebulae

A

They range from 50 to 300 light year across

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4
Q

What happens to the nebula over time

A

Over time the clouds contract, become denser and slowly heat up and break up into smaller clumps

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5
Q

What happens to the clumps once they get smaller

A

They flatten out into disk shapes

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6
Q

What happens to the center of each clump

A

It will eventually contain a star

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7
Q

What happens to the outer disk of gas and dust

A

It may eventually form planets around the star

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8
Q

What happens when the contracting clumps continue to heat up

A

A protostar is formed at the center

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9
Q

What is a protostar?

A

A protostar is a dense ball of gas that is not yet hot enough at the center to start nuclear reactions

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10
Q

How long does this stage last?

A

Roughly 50 million years

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11
Q

What happens as the collapse continues?

A

The mass of the protostar increases

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12
Q

What happens when the mass of the protostar increases

A

It squeezes it further and increases the temperature

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13
Q

How hot does a protostar need to be in order for nuclear fusion to take place

A

10 million degrees Celsius

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14
Q

What happens after nuclear fusion is able to take place

A

The protostar will technically be called a star

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15
Q

How does a young star start converting hydrogen to helium

A

Via nuclear fusion reaction

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16
Q

What type of energy is produced in vast amounts during nuclear reactions

A

Heat and light

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17
Q

What does this energy production do?

A

Prevents the star from contracting any further

18
Q

What does the star do when it shines?

A

Blows away the disk of dust and gas surrounding the star

19
Q

What happens during nuclear fusion

A

2 or more nuclei combine to form a large, single nucleus

20
Q

What are star winds called?

A

Stellar winds

21
Q

When is a star considered to be born?

A

Once nuclear fusion reaction begins at its center

22
Q

What is a main sequence star

A

A star that is converting hydrogen to helium

23
Q

How long can a star remain a main sequence star

A

Millions or billions of years

24
Q

When are stars most stable?

A

During their main sequence stage

25
Q

Which type of star comes in many different sizes and colors?

A

Main sequence stars

26
Q

What determines their colours

A

Their surface temperature

27
Q

How do you get stars look

A

They are hotter and blue in colour

28
Q

What happens to them once they age

A

They become more yellow and orange and slowly cool down

29
Q

How do older stars appear

A

Red and are vastly cooler in temperature

30
Q

What determines how long a main sequence star lives

A

How massive it is

31
Q

What happens when the hydrogen in the center of the star is depleted

A

He stars core shrinks and heats up

32
Q

What happens to the outer parts of the star when this happens?

A

It starts to expand

33
Q

What happens when a star becomes larger and brighter

A

It’s surface temperature cools and it glows red

34
Q

What happens in the next nuclear reaction

A

Atoms of helium collide and fuse into heavier elements such as carbon and oxygen

35
Q

After the helium i know the core is depleted, what determines the fate of the star

A

It’s mass

36
Q

What happens to medium sized stars

A

The temperature in the center will never get hot enough for a second nuclear fusion and they don’t evolve any further

37
Q

What follows the red giant phase?

A

The star becomes unstable and will eventually die

38
Q

What are the three stages of the death of stars

A
  • hydrogen starts to run out
  • other elements start to burn and give off more heat
  • star swells as surface cools —> red
39
Q

What are the stages of a medium sized star

A
  • star swells and becomes red giant
  • outer layer of gas are shed to form a planetary nebula (dust clouds)
  • core contacts into white dwarf (dead star)
40
Q

What are the stages of a large star?

A
  • turns yellow —> red —> super red giant
  • explodes as a supernova
  • a neutron star and a black hole are left behind
41
Q

What is a neutron star

A

Dense dead star

42
Q

What is a black hole?

A

Object with a large gravitational pull

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