21.The center of our galaxy lies in the direction of

Question : 21.The center of our galaxy lies in the direction of : 1777258

21.The center of our galaxy lies in the direction of (but far beyond) the stars in the constellation of
A.Ursa Minor.
B.Ursa Major.

A.is the process by which energy is produced at the center of the galaxy.
B.is the process by which hydrogen and helium are converted into heavier elements.
C.describes the structure of a globular cluster.
D.describes how the magnetic field of the galaxy traps cosmic rays.
E.describes the method by which neutral hydrogen produces 21 cm radiation.

23.The nuclear bulge of our galaxy
A.contains stars that are primarily population I stars.
B.is primarily composed of gas and dust.
C.contains stars primarily associated with the spherical component of our galaxy.
D.contains stars primarily associated with the disk component of our galaxy.
E.a, b and d

24.The orbits of population I stars


are confined to disk of the galaxy.


are very elliptical.


are nearly circular.


are randomly inclined to the disk of the galaxy.

C.I & IV

25.The traditional theory states that the galaxy formed
A.as a large spherical cloud of gas that was rotating very slowly.
B.from a large cloud of material that broke off a larger galaxy.
C.from material that had been ejected in the violent explosion of a dying galaxy.
D.as a result of mergers between several smaller groups of gas, dust, and stars.
E.as two massive galaxies collided.

26.The traditional theory of the formation of our galaxy cannot explain
A.the existence of the disk of the galaxy
B.the fact that the oldest stars in the galaxy are not metal free.
C.the spherical distribution of the globular clusters
D.the difference in metal abundance of the population I and II stars.
E.the existence of the nuclear bulge.

27.Radio maps of the spiral arms of our galaxy
A.reveal that our galaxy is a grand design spiral.
B.map the location of Hot O and B stars by the radio radiation they emit.
C.reveal that the spiral arms are winding up and growing closer together.
D.reveal that the sun is currently located in the center of a spiral arm.
E.map the location of dense neutral hydrogen clouds.

28.Sgr A* is believed to be the center of the Milky Way galaxy because


It lies in the general direction of the center of the galaxy based on observations of globular clusters in the plane of the Milky Way.


Long wavelength dust penetrating images show it to be a region crowded with stars


Orbits of stars around it indicate a mass several million times that of the Sun within a volume a few light hours in size


Radio observations show it is a concentrated source at the center of swirling clouds of gas

A.I & II only
B.II & III only
C.I & IV only
D.II & IV only
E.All of I, II, III, & IV

Refer to the figure. A Type II Cepheid has been located in a distant globular cluster with a period of 10 days. What is the star's absolute magnitude?
E.The absolute magnitude of a Cepheid variable cannot be determined unless its distance is known.

Refer to the figure. A Type I Cepheid has been located in an open cluster. The period of the Cepheid variable is 30 days and the variables apparent visual magnitude m is 10. First, use 12-1 to estimate the absolute visual magnitude, M . Calculate the distance to this open cluster? Hint: dpc = 10(m - M + 5)/5 using a scientific calculator.
A.100 pc
B.10,000 pc
C.20 pc
D.300 pc
E.2500 pc

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Astronomy 9 Months Ago 158 Views
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