Question :
41.What distance method did Edwin Hubble use to determine the : 1777266
41.What distance method did Edwin Hubble use to determine the distance to local galaxies?
A.Hubble Law
B.Supernova observations
C.Period-luminosity relationship of variable stars
D.Parallax
42.What distance methods is used to calibrate the Hubble constant?
A.Parallax
B.Supernova observations
C.variable stars
D.both a and b
E.both b and c
43.What distance method is used to determine the distance to the most distant galaxies?
A.Radar echo
B.Supernova observations
C.Period-luminosity relationship of variable stars
D.Parallax
44.What type of galaxies do astronomers believe to be the most common?
A.Elliptical
B.Spiral
C.Irregular
D.Astronomers have no idea which type of galaxy is more common.
45.The energy from an AGN is produced by
A.the collision of two spiral galaxies.
B.the collision of two elliptical galaxies.
C.the collision of two radio jets.
D.matter flowing into a supermassive black hole.
E.supernovae.
46.All ____ galaxies are spiral galaxies that have small luminous nuclei.
A.active
B.radio
C.Seyfert
D.double-lobed radio
E.blazar
47.In the double-exhaust model, the radio lobes of a radio galaxy are inflated by
A.jets of excited gas flowing from the central galaxy.
B.jets of high energy sound waves flowing from the central galaxy.
C.a disk of ionized material that orbits very near a supermassive black hole.
D.dark clouds of very cold gas and dust.
E.none of the above
48.The hot spots in double-lobed radio source
A.appear to coincide with the location of the central galaxy responsible for the jets.
B.are where hot excited gas interacts with the intergalactic medium.
C.are only found near quasars.
D.produce enough visible energy to be imaged at visible wavelengths.
E.are always perpendicular to each other.
49.A(n) ____ emits large amounts of energy but photographically appears to be a single point of light much like a star.
A.a planet like Venus
B.E galaxy
C.spiral galaxy
D.double-lobed radio galaxy
E.quasar
50.The radio lobes that are on each side of some radio galaxies and jets from them produce mainly
A.21-cm radiation.
B.synchrotron radiation.
C.black body radiation.
D.emission lies due to hydrogen.
E.absorption lines due to hydrogen.
