Untitled Qui

• What is the closest location you could find material formed in a supernova?

• The Sun

• Earth's core

• The Crab Nebula

• Your body

• The center of the Milky Way Galaxy

• Edwin Hubble measured the apparent brightness of Cepheid variable stars in galaxies to determine distances, and he found that the more-distant galaxies are moving away from us faster than less-distant galaxies.

• True

• False

Which one of the following statements about our Sun is TRUE?

• Both the core and the corona are much hotter than the photosphere.

• The Sun is a very active star, blasting waves of energy, solar flares, and winds continuously and uniformly with time.

• The apparent motion of sunspots on the Sun is caused mainly by Earth's orbit

• Being an uncharged (i.e. natural) star, the Sun does not have a magnetic field.

• Sunspots were first discovered recently, using telescopes in space.

Which one of the following statements about the Doppler-wobble method is FALSE?

• The Doppler wobble is caused by the reflex motion of a star that has an orbiting planet.

• The Doppler wobble method is larger for a planet that is far from a star than for one having the same mass that is near the star.

• The radial velocity of a star can be measured from its spectrum.

• The Doppler-wobble method which led to the discovery of most exoplanets initially, is now second to the transit method in the total number of detected exoplanets.

• The Doppler-wobble method generally provides only a planet's minimum mass.

In white dwarfs, brown dwarfs, and black dwarfs, "electron degeneracy pressure" prevents gravitational collapse. 

• True

• False

If you have already measured the surface temperature of star Medford, then to determine its radius you must also measure

• the amount of time it takes an exoplanet to transit across Medford's surface.

• the shift in stellar motion due to Doppler wobble.

• the changing position of star Medford throughout a night of observation.

• the wavelength of the peak of star Medford's spectrum

• the distance to Medford and its apparent brightness.

Which one of the following statements is FALSE?

• Pre-main-sequence stars shine by releasing gravitational potential energy while contracting and heating up.

• Main-sequence stars shine by converting most of the mass of atomic nuclei into energy according to the equation E=mc^2

• A main-sequence star becomes a red giant as its helium core contracts, releasing energy and causing a hydrogen-fusing shell to fuse more vigorously.

• At some point in time, a sufficiently massive red giant can shine by fusing helium to carbon and oxygen in its core.

• White dwarfs shine primarily because atomic nuclei lose their kinetic energy.

Suppose over the next year, Kyle goes outside (far away from any light pollution) on every clear night and counts individual stars with his unaided eyes (without binoculars, telescopes, or filters) along the plane of the Milky Way. What will he see? Why?

• He sees substantially more stars toward the center of the Milky Way Galaxy than away from the center; there are more stars near the center of the Milky Way Galaxy.

• He sees substantially more stars toward the center of the Milky Way Galaxy than away from the center; the nearest spiral arm to Earth is toward the center.

• He sees about the same number of stars toward the center of the Milky Way Galaxy and away from the center; dust absorbs and scatters much of the visible light from distant stars in the disk of the Milky Way Galaxy.

• He sees about the same number of stars toward the center of the Milky Way Galaxy and away from the center; we are very close to the center of the Milky Way Galaxy.

• He sees more stars away from the center of the Milky Way Galaxy than toward the center; the supermassive black hole at the center is preventing the visible light near the center from getting to us.

Which one of the following statements about active galactic nuclei (AGN) is FALSE?

• Jets of particles and light are sometimes seen originating from AGN.

• The luminosity of AGN depends on the rate at which matter is swallowed by the central supermassive black hole.

• The great width of the emission lines in AGN reveals the presence of supernovae ejecting matter at high speeds.

• The energy-generation mechanism in AGN is more efficient than nuclear fusion.

• The variability seen in AGN gives an upper limit (i.e., maximum value) on the physical size of the emitting region.

Which one of the following statements about core-collapse supernovae is FALSE?

• They explode primarily because of a runaway chain of nuclear reactions.

• They occur when the iron core mass reaches roughly the Chandrasekhar limit.

• They sometimes produce pulsars.

• They occur in very massive stars.

• They release most of their energy in the form of neutrinos.