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.
Reflection nebulae emit light from ionising hydrogen.
Extinction nebulae can only be formed by black holes.
Emission nebulae appear blue.
2. Stars in an open cluster are assumed to be
of the same surface temperature.
moving away from each other.
of the same spectral type.
of the same mass.
3. Hydrogen burning in stars
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.
produces water vapour in interstellar space.
4. Protostars heat up mostly due to
nuclear fusion.
radioactivity.
gravitational contraction.
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
only occurs in stars more massive than the Sun.
will occur in red giants.
produces helium nuclei.
produces hydrogen nuclei.
7. SN1987A
was a star which exploded in 1987.
is a faint white dwarf companion of the star SN1987.
is a binary star found in 1987 which emitted X-rays.
was a nova which occurred in 1987.
8. The Chandrasekhar limit is
the maximum mass of a white dwarf.
around ten times the solar mass.
the maximum radius of a red giant.
the radius of a black hole.
9. Neutron stars
emit a steady beam of neutrinos.
are detected by the neutrons they emit.
are generally thought to have a strong magnetic field.
are prevented from collapse by electron degeneracy pressure.
10. Black holes
cannot be directly observed.
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.
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