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.
Bok globules often emit infrared radiation.
Extinction nebulae can only be formed by black holes.
Reflection nebulae emit light from ionising hydrogen.
2. Stars in an open cluster are assumed to be
of the same spectral type.
of the same mass.
moving away from each other.
of the same surface temperature.
3. Hydrogen burning in stars
can occur via the proton-proton chain reaction.
is a reaction in which hydrogen fuses with oxygen.
is a nuclear reaction only occurring in the most massive stars.
produces water vapour in interstellar space.
4. Protostars heat up mostly due to
nuclear fusion.
nuclear fission.
radioactivity.
gravitational contraction.
5. Main sequence stars with higher luminosity than the Sun
are only observed in globular clusters.
must be red giants.
have a shorter lifetime than the Sun.
have a lower surface temperature 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.
is a binary star found in 1987 which emitted X-rays.
was a star which exploded in 1987.
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 maximum radius of a red giant.
the radius of a black hole.
9. Neutron stars
emit a steady beam of neutrinos.
are prevented from collapse by electron degeneracy pressure.
are generally thought to have a strong magnetic field.
are detected by the neutrons they emit.
10. Black holes
are caused absorption of light in cold, dense nebulae.
are the final stages of stars like the Sun.
are detected as dark clouds at the centre of galaxies.
cannot be directly observed.
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