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