Stars and Galaxies Flashcards
What is a star?
- An object in space
- (Thats emits light\0
Where is the energy that fuels the star coming from?
The energy for this light comes from nuclear fusion happening within the star
The birth of a star?
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
How will a nuclear fusion starts?
- The increase in temperatures (15 million ‘k )
- The pressures will reach a higher amount.
What is a galaxy?
Collection of stars, held together by gravitational attraction
How is the % of galaxies are found on there?
What is the % of galaxies are found clustered together and what are they called?
70% of galaxies are found clustered together.
These are called galaxy clusterss.
What are the two basic shapes of galaxies?
1) Elliptical galaxies
2) Spiral galaxies
What are the stages of the life cycle of a star which is
- Nebula
- Protostar
- Main sequence star
- Red Giant
- White Giant
- Black Dwarf
What are the stages of the life cycle of a star which is >10x the mass of sun, which ends in a neutron star?
- Nebula
- Protostar
- Main sequence star
- Red Super Giant
- Super nova
- Neutron star
What are the stages of the life cycle of a star which is
- Nebula
- Protostar
- Main sequence star
- Red Super Giant
- Super nova
- Black hole
What are the main properties of a red super giant star?
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
What is a supernova?
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
/What is a neutron star?
- 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
Do all elements emit the same light?
No different elements emit different light
What is the HR diagram and why is it useful?
- 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
How is a HR diagram plotted?
It plots stars according to their colour (i.e.temperature) and size
How do stars remain stable?
Stars remain stable as long as there is enough hydrogen to fuel the fusion reactions
In stars, what is there a balance between?
- The expansive force from the heat produced by the fusion reaction
- The force of gravity that ties to reduce the size of the star
What happens if all the hydrogen fuel becomes depleted?
The star will switch to HELIUM fusion which will make other elements.
What elements are made in helium fusion?
Carbon. This produces more energy and the star will start to expand
What is the final element that gets fused?
Iron.
Does iron absorb energy?
Fusion of elements that are larger than iron absorb energy.
What happens in iron fusion and why?
It absorbs energy and there is less expansive force, as gravity is the bigger force, the star will collapse on itself
How are heavier elements made?
They are made in supernovas
What are observations of the spectra of stars used for?
Deduce their composition
