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For gravitational lensing of a distant quasar to occur,the galaxy producing the lensing must:


A) be rotating rapidly to produce the requisite curvature of space to bend the light beam.
B) be almost perfectly placed on a line between Earth and the quasar.
C) contain a supermassive black hole at its center.
D) be a dwarf galaxy; otherwise, the quasar's light cannot pass through it and reach Earth.

E) A) and C)
F) C) and D)

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The estimated distance from Earth to the Coma cluster of galaxies is about:


A) 300 million ly.
B) 200 billion ly.
C) 2 million ly.
D) 10 ly.

E) C) and D)
F) B) and D)

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The Hubble relation links which two characteristics of distant objects in the universe?


A) distance and recessional velocity
B) luminosity and surface temperature
C) state of organization and the ages of clusters of stars
D) stellar mass and luminosity

E) All of the above
F) B) and D)

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What is an elliptical galaxy?


A) a galaxy with an elliptical outline and a smooth distribution of brightness but no apparent structure
B) a spiral galaxy seen from an angle, giving it an elliptical profile
C) a galaxy with an elliptical halo when observed at radio wavelengths
D) a spiral galaxy with an elliptically shaped nuclear bulge and the spiral arms starting from the ends of the ellipse

E) B) and C)
F) A) and C)

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The speed of the Sun in its orbit around the Milky Way Galaxy is deduced by reference to and observations of:


A) the orbital motions of stars near the Sun.
B) globular clusters and halo stars.
C) Cepheid variables, which provide a distance standard.
D) the galactic center, about which the Sun is orbiting.

E) C) and D)
F) All of the above

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Which arrangement is CORRECLTY listed according to size,from largest to smallest?


A) globular clusters, traditional dwarf elliptical, ultra compact dwarfs
B) globular clusters, ultra compact dwarfs, traditional dwarf elliptical
C) traditional dwarf elliptical, ultra compact dwarfs, globular clusters
D) ultra compact dwarfs, traditional dwarf galaxies, globular clusters

E) C) and D)
F) A) and C)

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According to the Hubble classification scheme,an E4 galaxy has a(n) :


A) disk and central bulge with a smooth light distribution and no spiral arms.
B) irregular shape.
C) round or spherical shape with a smooth light distribution and no disk or central bulge.
D) elliptical shape (a flattened circle) with a smooth light distribution.

E) All of the above
F) A) and B)

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Double-radio sources,quasars,and BL Lacertae objects are now considered to be the same basic type of object-an accretion disk producing two oppositely directed jets-but they appear to us to be very different because:


A) the relativistic particles ejected in the double jets are different in each case: electrons in double-radio sources, protons in quasars, and quarks in BL Lacertae objects.
B) they are at different distances from Earth, so we see more detail and different properties in those that are closer to Earth.
C) they are of different ages.
D) we view them at different angles to the line of the double jets. Face-on to the accretion disk the source will look like a BL Lacertae object, edge-on as double-radio sources, and between these positions a quasar.

E) A) and B)
F) A) and C)

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We have observed the central region of the Milky Way Galaxy in a number of wavelength ranges.With which one of the ranges is it MOST difficult to obtain information?


A) infrared
B) radio
C) visible
D) gamma ray

E) None of the above
F) All of the above

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What is the Local Group?


A) the stars that occupy the same spiral arm as the Sun
B) a cluster of about 40 galaxies, of which the Milky Way is one
C) a group of galaxies clustered around the Andromeda Galaxy M31, apparently gravitationally bound to it but separate from the Milky Way
D) a group of about 100 stars within 20 ly of the Sun that appear to have been formed at about the same time from similar material

E) C) and D)
F) B) and D)

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What is a hypervelocity star?


A) It is one of the stars in rapid orbital motion close to the supermassive black hole in the galactic center.
B) This is the name given to stars moving faster than escape speed from the galaxy.
C) This is the name given to a few stars that have been detected moving around the galactic center in the opposite direction from the general galactic rotation. Although their speeds are not unusual, their speeds relative to normal stars are very large.
D) These are stars that move around the galactic center in the middle of the galactic plane, but traveling much faster than neighboring stars-seemingly in defiance of Kepler's third law.

E) All of the above
F) B) and C)

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We aim our radio telescope at a distant region of the Milky Way Galaxy and detect 21-cm radio waves with no Doppler shift.Which possible explanation is NOT correct?


A) The neutral hydrogen in this region is not moving relative to Earth.
B) The neutral hydrogen in this region is moving perpendicularly across our line of sight.
C) The neutral hydrogen in this region is in a circular orbit around the galactic center at the same radius as the solar system.
D) The neutral hydrogen in this region is moving away from Earth instead of toward Earth.

E) All of the above
F) None of the above

Correct Answer

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BL Lacertae objects appear to be:


A) giant irregular galaxies with neither spiral arms nor the smooth shape of elliptical galaxies.
B) elliptical galaxies with bright, starlike nuclei.
C) spiral galaxies with bright, starlike nuclei.
D) active galaxies, most of whose energy is emitted by two widely spaced radio lobes.

E) A) and D)
F) B) and C)

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Spiral galaxies are classified in terms of increasing tightness of their spiral arms as types Sa,Sb,and Sc.However,many spiral galaxies are aligned edge-on to Earth and their spiral arms cannot be seen.Which other parameter that is directly related to spiral arm tightness can be easily seen edge-on and can therefore be used to provide this classification?


A) the overall spectral color
B) the overall intrinsic brightness of the galaxy, or its absolute magnitude
C) the size of the nuclear bulge
D) the overall diameter of the galaxy

E) B) and C)
F) A) and D)

Correct Answer

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What happens when the electron in a hydrogen atom flips its direction of spin from parallel to antiparallel to that of the proton?


A) Nothing. This event is a forbidden transition that never occurs.
B) The atom emits a photon of 656.3-nm wavelength (Hα) in the red region of the spectrum.
C) The atom emits a photon of 21-cm wavelength in the radio region of the spectrum.
D) The atom emits a photon of 121.5-nm wavelength (Lα) in the UV region of the spectrum.

E) All of the above
F) None of the above

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What is the Hubble classification for a spiral galaxy with a small nuclear region and loosely wound arms?


A) Sa
B) Sc
C) SBa
D) Sb

E) B) and C)
F) B) and D)

Correct Answer

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Which phenomenon is NOT produced by collisions between galaxies?


A) hot interstellar gas, detected by recent space-borne X-ray telescopes
B) concentration of galaxies into clusters and superclusters
C) distorted spiral arms in many galaxies
D) initiation of significant new star formation in so-called starburst galaxies

E) B) and D)
F) B) and C)

Correct Answer

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The energy output of a bright quasar is equivalent to:


A) that of the Milky Way Galaxy.
B) 10⁶ spiral galaxies.
C) 1000 Suns.
D) 100 bright galaxies.

E) C) and D)
F) All of the above

Correct Answer

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How are the Magellanic Clouds,the two nearby satellite galaxies of the Milky Way Galaxy,classified?


A) as elliptical galaxies
B) as irregular galaxies
C) as flocculent spiral galaxies
D) as grand-design spiral galaxies

E) A) and C)
F) All of the above

Correct Answer

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Which property is NOT characteristic of the center of the Milky Way Galaxy?


A) synchrotron (nonthermal) radiation produced by electrons spiraling in a powerful magnetic field
B) huge filaments of gas similar in structure to solar prominences
C) rapidly fluctuating emissions from a gigantic millisecond pulsar
D) halo of lobes of hot, ionized X-ray-emitting gas

E) None of the above
F) B) and C)

Correct Answer

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