71.If Hubble's constant taken to be 70 km/sec/Mpc, and a : 1777269
71.If Hubble's constant is taken to be 70 km/sec/Mpc, and a quasar is found with a radial velocity of 0.95 times the speed of light, how far away is the quasar?
72.If a quasar has a recessional velocity of 2.7´105 km/sec and is determined to be 3600 Mpc, what is the Hubble constant based on this quasar alone? Hint: Note that the units of your result should be (km/sec)/Mpc to see what arithmetic process you need to do on a calculator.
73.The hydrogen Balmer line Hb has a wavelength of 486.1 nm in the laboratory. It is observed in a quasar at 2430.5 nm. What is the change in wavelength (in nm) of this quasar? Is it a “redshift” or “blue shift” ?
A.0; no change
C.486.1; blue shift
74.The hydrogen Balmer line Hg has a wavelength of 434.0 nm in the laboratory. It is observed in a quasar at 651.0 nm. In terms of the speed of light, what is the recessional velocity of this quasar?
75.How are astronomers able to determine that quasars are so small?
A.They are variable over a short period of time.
B.They emit mainly X-rays.
C.They are only found at very large distance.
D.The structure of a quasar is completely resolved in images.
76.What is the major observational difference between a Seyfert galaxy and a normal spiral galaxy?
A.Normal spiral galaxies usually have shorter spiral arms.
B.Normal spiral galaxies never contain a supermassive black hole at their center.
C.The central region of a Seyfert galaxy is much brighter.
D.Seyfert galaxies don't contain any star formation.
77.How do astronomers know that the nuclei of some galaxies are active?
A.Their nuclei are much brighter than expected.
B.The orbits of stars near the center of the galactic nuclei are faster than expected.
C.The luminosity of the nuclei varies over time.
D.The color of the nuclei is different than expected.
78.Why do astronomers believe supermassive black holes are the source of an AGN's energy?
A.Such black holes have been found at the center of most galaxies both active and inactive.
B.Radio jets are seen from low mass black holes plus accretion disks inside our galaxy.
C.jets and accretion disks have been observed in active galaxies
D.black holes can produce so much energy in such a small place.
E.all of the above
79.Which is the most distant active galaxy?
D.BL Lac objects
80.How does the unified model of AGN explain blazars?
A.Blazars are Seyferts galaxies seen edge on.
B.Blazars are regions of the intergalactic medium where gas has been heated by a nearby AGN.
C.Blazars are relativistic jets from an AGN pointed toward our light of sight.
D.Blazars are newly formed AGN from a recently galactic collision.
81.How does the study of quasars reveal information of the history of the universe?
A.Typical quasars are very distant so we can view how galaxy evolution occurred in the past.
B.Quasars contain stars of all ages.
C.Quasars typically act as host galaxies for gravitational lensing.
D.Quasars generate their energy in very small volumes of space