Exploring the Cosmos - Degree Exam 2007 - Life and Death of Stars (Part 2)
1. Which of the following statements is TRUE?
Extinction nebulae can only be formed by black holes.
Bok globules often emit infrared radiation.
Emission nebulae appear blue.
Reflection nebulae emit light from ionising hydrogen.
2. Stars in an open cluster are assumed to be
moving away from each other.
of the same spectral type.
of the same surface temperature.
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.
nuclear fission.
gravitational contraction.
radioactivity.
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
will occur in red giants.
produces helium nuclei.
produces hydrogen nuclei.
only occurs in stars more massive than the Sun.
7. SN1987A
was a nova which occurred in 1987.
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.
8. The Chandrasekhar limit is
the maximum radius of a red giant.
the maximum mass of a white dwarf.
the radius of a black hole.
around ten times the solar mass.
9. Neutron stars
are prevented from collapse by electron degeneracy pressure.
are detected by the neutrons they emit.
are generally thought to have a strong magnetic field.
emit a steady beam of neutrinos.
10. Black holes
cannot be directly observed.
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.
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