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