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.
Extinction nebulae can only be formed by black holes.
Emission nebulae appear blue.
Reflection nebulae emit light from ionising hydrogen.
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
can occur via the proton-proton chain reaction.
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.
4. Protostars heat up mostly due to
gravitational contraction.
nuclear fusion.
radioactivity.
nuclear fission.
5. Main sequence stars with higher luminosity than the Sun
have a shorter lifetime than the Sun.
have a lower surface temperature 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 hydrogen nuclei.
produces helium nuclei.
7. SN1987A
was a star which exploded in 1987.
is a binary star found in 1987 which emitted X-rays.
is a faint white dwarf companion of the star SN1987.
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.
around ten times the solar mass.
the radius of a black hole.
9. Neutron stars
are detected by the neutrons they emit.
are prevented from collapse by electron degeneracy pressure.
emit a steady beam of neutrinos.
are generally thought to have a strong magnetic field.
10. Black holes
are the final stages of stars like the Sun.
cannot be directly observed.
are caused absorption of light in cold, dense nebulae.
are detected as dark clouds at the centre of galaxies.
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