Exploring the Cosmos - Degree Exam 2007 - Life and Death of Stars (Part 2)
1. Which of the following statements is TRUE?
Reflection nebulae emit light from ionising hydrogen.
Emission nebulae appear blue.
Extinction nebulae can only be formed by black holes.
Bok globules often emit infrared radiation.
2. Stars in an open cluster are assumed to be
of the same surface temperature.
moving away from each other.
of the same mass.
of the same spectral type.
3. Hydrogen burning in stars
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.
is a reaction in which hydrogen fuses with oxygen.
4. Protostars heat up mostly due to
nuclear fusion.
nuclear fission.
radioactivity.
gravitational contraction.
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
produces hydrogen nuclei.
will occur in red giants.
produces helium nuclei.
only occurs in stars more massive than the Sun.
7. SN1987A
was a star which exploded in 1987.
was a nova which occurred 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
around ten times the solar mass.
the radius of a black hole.
the maximum mass of a white dwarf.
the maximum radius of a red giant.
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 detected as dark clouds at the centre of galaxies.
are caused absorption of light in cold, dense nebulae.
are the final stages of stars like the Sun.
cannot be directly observed.
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