Exploring the Cosmos - Degree Exam 2007 - Life and Death of Stars (Part 2)
1. Which of the following statements is TRUE?
Bok globules often emit infrared radiation.
Extinction nebulae can only be formed by black holes.
Reflection nebulae emit light from ionising hydrogen.
Emission nebulae appear blue.
2. Stars in an open cluster are assumed to be
of the same surface temperature.
moving away from each other.
of the same mass.
of the same spectral type.
3. Hydrogen burning in stars
produces water vapour in interstellar space.
is a reaction in which hydrogen fuses with oxygen.
can occur via the proton-proton chain reaction.
is a nuclear reaction only occurring in the most massive stars.
4. Protostars heat up mostly due to
nuclear fusion.
gravitational contraction.
nuclear fission.
radioactivity.
5. Main sequence stars with higher luminosity than the Sun
are only observed in globular clusters.
must be red giants.
have a lower surface temperature than the Sun.
have a shorter lifetime than the Sun.
6. The triple alpha reaction is a nuclear reaction which
only occurs in stars more massive than the Sun.
produces hydrogen nuclei.
will occur in red giants.
produces helium nuclei.
7. SN1987A
is a faint white dwarf companion of the star SN1987.
was a nova which occurred in 1987.
is a binary star found in 1987 which emitted X-rays.
was a star which exploded in 1987.
8. The Chandrasekhar limit is
the radius of a black hole.
the maximum radius of a red giant.
around ten times the solar mass.
the maximum mass of a white dwarf.
9. Neutron stars
are detected by the neutrons they emit.
are generally thought to have a strong magnetic field.
are prevented from collapse by electron degeneracy pressure.
emit a steady beam of neutrinos.
10. Black holes
are the final stages of stars like the Sun.
cannot be directly observed.
are caused absorption of light in cold, dense nebulae.
are detected as dark clouds at the centre of galaxies.
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