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