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