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