b) When the element at the center runs out, what sort of object do the stars become? (1 mark)
c) If the mass of the star is >0.7Msun, what element can now burn? What element is created? (2 marks)
d) What happens to the outer layers of low mass stars? What are these outer layers called? (2marks)
e) What objects do low mass stars end up as? (1 mark)
2. a) What is the final element created in the center of a high mass (M>5Msun) star? (1 mark)
b) What happens to the core of the high mass star after this element is created? (1 mark)
c) What happens to the outer layers of high mass stars (1 mark)
d) What sort of object will the high mass star end up as? (1 mark)
3. a) Gravity causes anything with a mass to collapse onto itself, yet stars are not collapsed objects. What supports gravity when a star is in the main sequence phase? (1 mark)
b) Briefly describe the pressure that supports a white dwarf from collapse due to gravity? (2 marks)
4. The main-sequence lifetime of a star is approximately proportional to mass^{-3} (t = 1/m^3). The sun has a mass of 1M_sun and has a life time of 10 billion years. What would be the lifetime of a 10M_sun? (2 marks)
b) What would be the lifetime of a 0.1M_sun? (2 marks)
c) The Universe is 15 billion years old. If the 10M_sun, 1M_sun and the 0.1M_sun were all formed at the very start of the Universe, what evolutionary stage would these stars be in now? (3 marks)
5. a) (Week 2 revision) A white dwarf has a mass of 1M_sun and a radius of 0.01R_sun. By what factor is the acceleration due to gravity larger on the white dwarf than it is on the Sun? (2 marks)
b) Imagine we can send a satellite to this white dwarf and place it in orbit around it at a distance of 2 AU. What would it's rotation period be? (2 marks)