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 surface temperature.
of the same spectral type.
moving away from each other.
of the same mass.
3. Hydrogen burning in stars
can occur via the proton-proton chain reaction.
produces water vapour in interstellar space.
is a nuclear reaction only occurring in the most massive stars.
is a reaction in which hydrogen fuses with oxygen.
4. Protostars heat up mostly due to
nuclear fusion.
gravitational contraction.
radioactivity.
nuclear fission.
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.
produces helium nuclei.
only occurs in stars more massive than the Sun.
produces hydrogen nuclei.
7. SN1987A
is a binary star found in 1987 which emitted X-rays.
is a faint white dwarf companion of the star SN1987.
was a star which exploded in 1987.
was a nova which occurred in 1987.
8. The Chandrasekhar limit is
the maximum mass of a white dwarf.
the maximum radius of a red giant.
the radius of a black hole.
around ten times the solar mass.
9. Neutron stars
emit a steady beam of neutrinos.
are generally thought to have a strong magnetic field.
are prevented from collapse by electron degeneracy pressure.
are detected by the neutrons they emit.
10. Black holes
are detected as dark clouds at the centre of galaxies.
are the final stages of stars like the Sun.
are caused absorption of light in cold, dense nebulae.
cannot be directly observed.
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