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 neutron star formation in solar-like stars.
prevents the Sun from collapsing within a few years.
2. Globular clusters
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.
are found in elliptical but not spiral galaxies.
3. Black holes
can never be observed.
have never been observed.
are often observed by their tidal effect on the Earth.
are often observed due to their tidal effect on nearby matter.
4. Neutrinos
are too weak to have any effect.
carry most of the energy away from a type-II supernova.
cause massive stars to collapse.
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.
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.
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 mass of dust in the cluster.
count the number of stars in the cluster.
estimate the age of the cluster.
estimate the distance to the cluster.
7. Neutron stars
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.
can rotate at a rate of more than 100 revolutions per second.
contain most of the neutrinos in the known Universe.
8. Open clusters are
several galaxies weakly bound by gravity.
several stars weakly bound by gravity.
any number of stars in a group.
an unnamed constellation.
9. T Tauri stars, EGGs and Bok globules are associated with
star birth.
main sequence stars.
most pulsars.
star death.
10. Pulsars
have not yet been detected.
pulse uniformly over their whole surface in a perfectly synchronised manner.
are made of neutrons and so have zero electric and magnetic ï¬eld.
are known to be nearly perfect spheres.
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