Questions on Stars
1. any 4 from:
end of H burning/red giant/supergiant (1)
onset of He fusion/fusion of heavier nuclei (1)
gravitational collapse of core (1)
supernova explosion/ star explodes (1)
suitable mass limit (chanderasekha limit 1.4M) (1)
supported against gavity by neutron gas pressure/ ref to
Fermi pressure (1)
internal structure protons and electrons combined/ very
thin atmosphere/ metallic crust (1) 4
[4]
2. Any 5 from
red shift data for galaxies (accept stars) 1
calculate velocity from red shift 1
galaxies/ stars receding from Earth 1
distance data for galaxies/ stars 1
velocity α distance / v/r = constant / v-r graph straight line 1
universe began at a single point 1
[5]
3. (a) Any two
stars rotate around galactic centre 1
star with velocity component towards Earth 1
reference to motion/shape of galaxy 1
or other valid points eg blue shift
(b) Ho = 75/ 3 × 1019 s–1 1
t ≈ 1/ 2.5 × 10–18 1
t ≈ 4 × 1017 s 1
[5]
4. Hydrogen atoms/particles (1)
Collapse under gravity/ decrease of gpe (1)
Increase in kinetic energy/ temperature (1)
Fusion of protons (1)
Energy released/ ref. to E = ∆mc2 (1)
[5]
5. Any 6 from
Nuclear/hydrogen burning ends (1)
Mass > Chandrasekhar limit (1)
Expanding gas/planetary nebular/red giant (1)
Gravitational collapse /ref. to burning He or higher metals (1)
Correct ref. to (Fermi) pressure/ radiation pressure (1)
(must have ref. to pressure or force from radiation.)
Neutron star (neutron by itself, not enough) (1)
Correct reference to Schwarzschild radius/
allow mass> 3M/ allow ref. critical radius (1)
Black Hole (1) 6
[6]
6. Ho2 = (1 × 10–26 × 8 × π × 6.67 × 10–11) / 3 C1
Ho = 2.36 × 10–18 s–1 A1
[2]
7. (i) v/c = ∆λ / λ (1)
∆λ = 656.3 × 10–9 × 6.1 / 3 × 108 (ignore minus sign) (1)
∆λ = 1.33 × 10–14 m (1) 3
(ii) Graph: any 4 points plotted correctly (1)
all correct (1) 2
(iii) graph: draw curve, reasonable attempt (1) 1
(iv) Either point where star moves perpendicular to line of sight (1) 1
(v) time = 72 h ± (1)h (ecf read value from their graph ± 1 h) (1) 1
(vi) r = 3√(6.7 × 10–11 × 4 × 1030 × [72 × 3600]2/ 4π2) ecf (1)
r = 7.70 × 109 m ecf . (1) 2
(use of t = 72h 1/2)
[10]
