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.
Extinction nebulae can only be formed by black holes.
Bok globules often emit infrared radiation.
2. Stars in an open cluster are assumed to be
of the same mass.
of the same surface temperature.
of the same spectral type.
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 fission.
gravitational contraction.
radioactivity.
nuclear fusion.
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
only occurs in stars more massive than the Sun.
will occur in red giants.
produces helium nuclei.
produces hydrogen nuclei.
7. SN1987A
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.
is a faint white dwarf companion of the star SN1987.
8. The Chandrasekhar limit is
the radius of a black hole.
around ten times the solar mass.
the maximum mass of a white dwarf.
the maximum radius of a red giant.
9. Neutron stars
are generally thought to have a strong magnetic field.
are prevented from collapse by electron degeneracy pressure.
are detected by the neutrons they emit.
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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