Download Problem set 1 1. The binding energy per nucleon for 56Fe is 8.8MeV

Problem set 1
1. The binding energy per nucleon for 56 Fe is 8.8 MeV per nucleon. Estimate the total energy released per kilogram of matter by the sequence
of reactions which fuse hydrogen to iron.
2. The main sequence of the Pleiades cluster of stars consists of stars with
mass less than 6M ; the more massive stars have already evolved off
the main sequence. Estimate the age of the Pleiades cluster.
3. Given that the luminosity of the sun is 3.8 × 1026 W and that the absolute bolometric magnitude of the sun is M ≈ 4.7, estimate the distance
at which the sun could just be seen by the naked eye (The naked eye
can detect a star of apparent magnitude 6). The apparent magnitude,
m, is related to the absolute magnitude, M , by
m = M + 5 log
d
.
10pc
(1)
Estimate the number of photons incident on the eye per second in this
situation.
4. Sketch the HR diagram for an old globular cluster, label the main
sequence, the red giant and horizontal branch. (2001 final exam, 3
marks)
Write down the approximate observed range of stellar masses. What
imposes the lower and upper limits on the mass of stars? [2001 final
exam, 5 marks]
Using the observed mass-luminosity relation for nearby stars, argue
stars must be forming at present day. [2002 final exam, 5 marks]