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