Exploring the Cosmos - Degree Exam 2014 - Life and Death of Stars (Part 2)
1. Electron degeneracy
prevents the Sun from collapsing within a few years.
causes pulsars to have a strong magnetic ï¬eld.
prevents black hole formation in massive stars.
prevents neutron star formation in solar-like stars.
2. Globular clusters
are found in elliptical but not spiral galaxies.
contain mainly stars of low metallicity.
are probably the largest clusters of stars in the Universe.
are recently formed collections of approximately 10^6 stars.
3. Black holes
are often observed due to their tidal effect on nearby matter.
have never been observed.
can never be observed.
are often observed by their tidal effect on the Earth.
4. Neutrinos
are too weak to have any effect.
cause massive stars to collapse.
carry most of the energy away from a type-II supernova.
are mainly associated with type Ia supernovae.
5. A main-sequence star 10 times as massive as the Sun
obtains most of its energy by the triple alpha process.
has a core temperature that is much higher than that of the Sun.
is much denser than the Sun so has roughly the same diameter.
has about 10 times the amount of hydrogen and so burns approximately 10 times longer than the Sun.
6. Analysis of the H-R diagram for a cluster is a good means to
estimate the distance to the cluster.
count the number of stars in the cluster.
estimate the age of the cluster.
estimate the mass of dust in the cluster.
7. Neutron stars
contain most of the neutrinos in the known Universe.
can rotate at a rate of more than 100 revolutions per second.
are very dense and so cannot rotate faster than about once an hour.
are about the same density as white dwarfs, but made of nuclear material.
8. Open clusters are
several galaxies weakly bound by gravity.
an unnamed constellation.
several stars weakly bound by gravity.
any number of stars in a group.
9. T Tauri stars, EGGs and Bok globules are associated with
main sequence stars.
star birth.
star death.
most pulsars.
10. Pulsars
are made of neutrons and so have zero electric and magnetic ï¬eld.
are known to be nearly perfect spheres.
pulse uniformly over their whole surface in a perfectly synchronised manner.
have not yet been detected.
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