Stellar characteristics and evolution

Question 2

Info star spectrum can give for a star

Answer 2

1. surface temperature
2. chemical composition
3. velocity&rotation
4. magnetic field

Question 3

Features of Hertzsprung-Russel diagram

Answer 3

1. Luminosities in terms of that of sun
2. Most stars fall within diagonal strip called main sequence
3. Top right: red giants and super giants
4. Bottom left: white dwarfs

Question 4

Spectral classes of stars in increasing surface temperature

Answer 4

• O
• B
• A
• F
• G
• K
• M

Oh Be A Fine Guy, Kiss Me!

Question 5

Cepheid variable stars

Answer 5

Stars whose luminosity varies periodically between a minimum and a maximum

Question 6

Outline cycle of cepheid variables:

Answer 6

1. Helium atoms ionised by radiation
2. Free electrons collide, heating star
3. Causes pressure increase; star expands
4. Radiation leaves once most helium is ionised
5. Star cools and contracts under its weight
6. Helium nuclei recombine with electrons
7. Process repeats