Stellar Evolution Flashcards
What is the order of star classification?
O, B, A, F, G, K, M
(O, B A Fine Girl Kissed Me)
(Oh Babygronk A Feinious Gyat Kame-on Me)
How are stars classified?
By their colour and surface temperature.
What are the features of B Class Stars?
- Light blue
- 10,000-28,000K
- Contain Helium and Hydrogen
What are the features of O Class Stars?
- Dark Blue
- 28,000-50,000K
- Hottest type of star
- Contain ionised Helium and regular Helium
What are the features of A Class Stars?
- White
- 7,500-10,000K
- Contain strong Hydrogen and some ionised metals
What are the features of F Class Stars?
- Yellow/white
- 6,000-7,500K
- Contain Hydrogen and ionised metals.
What are the features of G Class Stars?
- Yellow
- 5,000-6,000K
- Contain metals and ionised metals
Apparent magnitude
A measure of how bright a star is as seen from Earth
What are the features of K Class Stars?
- Orange
- 3500-5000K
- Contain metals
What are the features of M Class Stars?
- Red
- 2500-3500K
- Contain strong titanium oxide and some calcium
- Coldest type of star
What is a nebula?
Cloud of dust and gas
What is the Stage 1 of Star Formation?
Nebula (cloud of dust and gas)
-The attractive force of gravity pulls the dust and gas together
What is the Stage 2 of Star Formation?
Protostar
- The dust and gas collapse as the gravitational attraction increases.
- As the cloud collapses, it heats up.
What is the Stage 3 of Star Formation?
Main Sequence (stability)
- A protostar becomes a stable star when nuclear fusion begins in the star’s core when it becomes hot enough.
- The inward gravitational force is balanced to the outward radiation pressure.
- Lasts billions of years.
What is absolute magnitude?
A measure of how bright a star is from a standard distance away from earth (10pc)
How far is 10 parsecs?
32.6 light years away from Earth
What type of main sequence stars form red supergiants?
Stars with much bigger than the sun
What type of main sequence stars form red giants?
Stars with are about the same size as the sun
How is a Red Giant/ Supergiant formed?
Hydrogen in the core runs out so gravity is stronger than thermal expansion, so star compresses which makes it hot, the outer layers expand and become red because the surface is cooler
What is thermal expansion?
The energy produced by nuclear fusion tries to expand the star
What does a Red Giant form and what is it?
A white dwarf - The outer layer of gas is ejected leaving a hot core (the white dwarf)
What can a Red Supergiant form and what is it?
A supernova - Fusion of elements making heavier elements and the explode forming a supernova
What can be formed from a supernova?
A neutron star or black hole
What is a Neutron star?
Supernova throws off the outer layer of gas leaving a dense core
What is a Black hole?
If star was very big it collapses to form a dense point that even light can’t escape from
What does the HR diagram show?
That white dwarfs are very hot but small so they are dim
Red giants + supergiants are cool and very large so they are very bright
Main sequence stars are similar sizes, those with higher temperatures are very bright, those with very low temperatures are dim
Unit of mass
Kilogram (Kg)
Unit of length
Metre (m)
Unit of speed/ velocity
Metre/ second (m/s)
Unit of acceleration
Metre/ second^2 (m/s^2)
Unit of force
Newtons (N)
Unit of time
Second (s)
Unit of gravitational force
Newton/ kilogram (N/Kg)
