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