Stars and Galaxies

Question 1

What is a star?

Answer 1

• An object in space

- (Thats emits light\0

Question 2

Where is the energy that fuels the star coming from?

Answer 2

The energy for this light comes from nuclear fusion happening within the star

Question 3

The birth of a star?

Answer 3

Gas particles in space are weakly attracted to each other by gravity. As they move together they are more likely to bump into each other. This will increase the temperature of the atoms

Question 4

How will a nuclear fusion starts?

Answer 4

• The increase in temperatures (15 million ‘k )

- The pressures will reach a higher amount.

Question 5

What is a galaxy?

Answer 5

Collection of stars, held together by gravitational attraction

Question 6

How is the % of galaxies are found on there?

Question 7

What is the % of galaxies are found clustered together and what are they called?

Answer 7

70% of galaxies are found clustered together.

These are called galaxy clusterss.

Question 8

What are the two basic shapes of galaxies?

Answer 8

1) Elliptical galaxies

2) Spiral galaxies

Question 9

What are the stages of the life cycle of a star which is

Answer 9

• Nebula
• Protostar
• Main sequence star
• Red Giant
• White Giant
• Black Dwarf

Question 10

What are the stages of the life cycle of a star which is >10x the mass of sun, which ends in a neutron star?

Answer 10

• Nebula
• Protostar
• Main sequence star
• Red Super Giant
• Super nova
• Neutron star

Question 11

What are the stages of the life cycle of a star which is

Answer 11

• Nebula
• Protostar
• Main sequence star
• Red Super Giant
• Super nova
• Black hole

Question 12

What are the main properties of a red super giant star?

Answer 12

The star begins to fuse together heavier elements. But because it has more fuel, it becomes a much larger size and gives off much more energy

Question 13

What is a supernova?

Answer 13

When it is a very heavy star, and they have run out of fuel, the star begins to collapse on itself. It continues to collapse until it reaches a critical point when it can’t collapse any more. This results in a massive shock wave

Question 14

/What is a neutron star?

Answer 14

• Sometimes the core of the collapsed star survives the supernova
• If the core is less than 3x the mass of our own sun then it turns in a ‘neutron star’
• They are very dense

Question 15

Do all elements emit the same light?

Answer 15

No different elements emit different light

Question 16

What is the HR diagram and why is it useful?

Answer 16

• Hertzsprung-Russell diagram
• It mirrors the life cycle of stars
• It is useful because scientists like classifying stars using their colour, brightness of their light and their sizes

Question 17

How is a HR diagram plotted?

Answer 17

It plots stars according to their colour (i.e.temperature) and size

Question 18

How do stars remain stable?

Answer 18

Stars remain stable as long as there is enough hydrogen to fuel the fusion reactions

Question 19

In stars, what is there a balance between?

Answer 19

• The expansive force from the heat produced by the fusion reaction
• The force of gravity that ties to reduce the size of the star

Question 20

What happens if all the hydrogen fuel becomes depleted?

Answer 20

The star will switch to HELIUM fusion which will make other elements.

Question 21

What elements are made in helium fusion?

Answer 21

Carbon. This produces more energy and the star will start to expand

Question 22

What is the final element that gets fused?

Answer 22

Iron.

Question 23

Does iron absorb energy?

Answer 23

Fusion of elements that are larger than iron absorb energy.

Question 24

What happens in iron fusion and why?

Answer 24

It absorbs energy and there is less expansive force, as gravity is the bigger force, the star will collapse on itself

Question 25

How are heavier elements made?

Answer 25

They are made in supernovas

Question 26

What are observations of the spectra of stars used for?

Answer 26

Deduce their composition