IGCSE Astrophysics Stars

How can stars be classified

According to their colour

A star's color is related to its?

Surface temperature

How is the brightness of a star at a standard distance represented.

Using absolute magnitude

Why is it necessary to specify the brightness of a star at a standard distance?

Because the observed (apparent) brightness decreases with distance.

describe the past evolution of the universe

Big Bang, Inflation, CMBR formed. Dark ages, First stars formation, Galaxy formation, expansion.

What are the main arguments in favour of the Big Bang

Red-shift and cosmic microwave background (CMB) radiation

What is the doppler effect

if a wave source is moving relative to an observer there will be a change in the observed frequency and wavelength

How does the red-shift in light received from galaxies at different distances away from the Earth vary

The further away the star is, the greater the redshift. ie the faster it is moving away.

protostar

Becoming a star but its core is not yet hot enough for fusion to take place.

main sequence star

Gravity and the high temperature and pressure from fusion is balanced

red giant

Most of the hydrogen is used up and the core collapse but the outer layers expand.

Supernova

The whole star collapse then explodes

Massive main sequence star's lifespan is

shorter

What are the axis on a Hertzsprung Russell diagram?

Luminosity and temperature

What is strange about the axis on a Hertzsprung Russell diagram?

Temperature axis is reversed