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11. The question regarding why galaxies have different shapes relates to both the origin and evolution of a galaxy. These in turn depend on a variety of factors such as how large a particular proto-galaxy was, how many neighboring galaxies are formed (cluster), the rotation rate of the proto-galaxy, how quickly stars form, how many collisions the galaxy experiences, and other properties. The importance of any one factor is under active research. Complete parts a-g of this question. a. The drawings below represent a side view of four different rotating protogalaxies. Assuming that each one started out approximately spherical in shape, and considering that the rate of rotation influences the shape, put in a number positions of stars at different distances from the nucleus of the galaxy. Assume the motion of stars at A, B and C are such, that the time it takes A to go around the nucleus once, B goes around twice, and C goes around four times. Diagram 2 illustrates the positions of stars A, B and C after A has gone 4 of a rotation. Note that in the same time, stars at B have gone twice as far along their orbit and stars at C, 4 times as far. By connecting the stars at their new positions: and intermediate points between these stars, the spiral structure for one arm of the galaxy becomes apparent. Applying these ideas, draw the shape of the spiral arm, on diagram 3, after stars originally at position A have moved half way around the galaxy.

11. The question regarding why galaxies have different shapes relates to both the origin and evolution of a galaxy. These in turn depend on a variety of factors such as how large a particular proto-galaxy was, how many neighboring galaxies are formed (cluster), the rotation rate of the proto-galaxy, how quickly stars form, how many collisions the galaxy experiences, and other properties. The importance of any one factor is under active research. Complete parts a-g of this question. a. The drawings below represent a side view of four different rotating protogalaxies. Assuming that each one started out approximately spherical in shape, and considering that the rate of rotation influences the shape, put in a number positions of stars at different distances from the nucleus of the galaxy. Assume the motion of stars at A, B and C are such, that the time it takes A to go around the nucleus once, B goes around twice, and C goes around four times. Diagram 2 illustrates the positions of stars A, B and C after A has gone 4 of a rotation. Note that in the same time, stars at B have gone twice as far along their orbit and stars at C, 4 times as far. By connecting the stars at their new positions: and intermediate points between these stars, the spiral structure for one arm of the galaxy becomes apparent. Applying these ideas, draw the shape of the spiral arm, on diagram 3, after stars originally at position A have moved half way around the galaxy.

Applications and Investigations in Earth Science (9th Edition)
Applications and Investigations in Earth Science (9th Edition)
9th Edition
ISBN:9780134746241
Author:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa
Publisher:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa
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C 11. The question regarding why galaxies have different shapes relates to both the origin and evolution of a galaxy. These in turn depend on a variety of factors such as how large a particular proto-galaxy was, how many neighboring galaxies are formed (cluster), the rotation rate of the proto-galaxy, how quickly stars form, how many collisions the galaxy experiences, and other properties. The importance of any one factor is under active research. Complete parts a-g of this question. a. The drawings below represent a side view of four different rotating protogalaxies. Assuming that each one started out approximately spherical in shape, and considering that the rate of rotation influences the shape, put in a number from 1-4 below each diagram starting with I for the slowest rotation. positions of stars at different distances from the nucleus of the galaxy. Assume the motion of stars at A, B and C are such, that the time it takes A to go around the nucleus once, B goes around twice, and C goes around four times. Diagram 2 illustrates the positions of stars A, B and C after A has gone 4 of a rotation. Note that in the same time, stars at B have gone twice as far along their orbit and stars at C, 4 times as far. By connecting the stars at their new positions and intermediate points between these stars, the spiral structure for one arm of the galaxy becomes apparent. Applying these ideas, draw the shape of the spiral arm, on diagram 3, after stars originally at position A have moved half way around the galaxy. Axis of Rotation Axis of Rotation b. If rotation is an important protogalaxy property, which type of Hubble class galaxy represents the fastest protogalaxy rotation rate? c. One theory regarding the differences in the sub-classes of spiral galaxies is based on the hypothesis that protogalaxies are approximately spherical in shape. The differences subsequent- ly develop as star formation begins in the protogalaxy. The cause of the differences is that stars tend not to loose their space motion perpendicular to the "equator" of the galaxy because of their mass and relatively small size. Thus the motion of stars "remembers" the earlier distribution of mass in the protogalaxy. However, until the dust and gas form stars, it can interact, loose this perpendicular motion and form a disk. Of the galaxies in images B, F and I on the Supplementary Data Sheet, which most likely experienced the earliest star formation? d. Two natural types of rotation are: 1) rigid body rotation in which all parts of an object have the same period of rotation, and 2) differential rotation in which the rotational period decreases as we go away from the center of rotation. In diagram 1, in the next column, A, B and C are shown in a straight alignment representing the 3 e. Which of the drawings below best represents the spiral structure of the galaxy in part d after one rotation of star A? Note that two spiral arms. have been illustrated in each diagram. f. Most spiral galaxies only show 1 to 1½ rotations of the spiral arms, but the universe is known to be old enough for most regions of outer stars of spiral galaxies to have completed more than five rotations. Explain why this observation proves differential rotation is not the cause of a spiral pattern. g. The diagrams below show the results of a com- puter calculation showing the close approach of two normal galaxies. Which galaxy on the back of the Supplemental Data Sheet looks the most like the result of this simulated near miss? 3 (A. and Toome) (AD Hale O 8
Transcribed Image Text:C 11. The question regarding why galaxies have different shapes relates to both the origin and evolution of a galaxy. These in turn depend on a variety of factors such as how large a particular proto-galaxy was, how many neighboring galaxies are formed (cluster), the rotation rate of the proto-galaxy, how quickly stars form, how many collisions the galaxy experiences, and other properties. The importance of any one factor is under active research. Complete parts a-g of this question. a. The drawings below represent a side view of four different rotating protogalaxies. Assuming that each one started out approximately spherical in shape, and considering that the rate of rotation influences the shape, put in a number from 1-4 below each diagram starting with I for the slowest rotation. positions of stars at different distances from the nucleus of the galaxy. Assume the motion of stars at A, B and C are such, that the time it takes A to go around the nucleus once, B goes around twice, and C goes around four times. Diagram 2 illustrates the positions of stars A, B and C after A has gone 4 of a rotation. Note that in the same time, stars at B have gone twice as far along their orbit and stars at C, 4 times as far. By connecting the stars at their new positions and intermediate points between these stars, the spiral structure for one arm of the galaxy becomes apparent. Applying these ideas, draw the shape of the spiral arm, on diagram 3, after stars originally at position A have moved half way around the galaxy. Axis of Rotation Axis of Rotation b. If rotation is an important protogalaxy property, which type of Hubble class galaxy represents the fastest protogalaxy rotation rate? c. One theory regarding the differences in the sub-classes of spiral galaxies is based on the hypothesis that protogalaxies are approximately spherical in shape. The differences subsequent- ly develop as star formation begins in the protogalaxy. The cause of the differences is that stars tend not to loose their space motion perpendicular to the "equator" of the galaxy because of their mass and relatively small size. Thus the motion of stars "remembers" the earlier distribution of mass in the protogalaxy. However, until the dust and gas form stars, it can interact, loose this perpendicular motion and form a disk. Of the galaxies in images B, F and I on the Supplementary Data Sheet, which most likely experienced the earliest star formation? d. Two natural types of rotation are: 1) rigid body rotation in which all parts of an object have the same period of rotation, and 2) differential rotation in which the rotational period decreases as we go away from the center of rotation. In diagram 1, in the next column, A, B and C are shown in a straight alignment representing the 3 e. Which of the drawings below best represents the spiral structure of the galaxy in part d after one rotation of star A? Note that two spiral arms. have been illustrated in each diagram. f. Most spiral galaxies only show 1 to 1½ rotations of the spiral arms, but the universe is known to be old enough for most regions of outer stars of spiral galaxies to have completed more than five rotations. Explain why this observation proves differential rotation is not the cause of a spiral pattern. g. The diagrams below show the results of a com- puter calculation showing the close approach of two normal galaxies. Which galaxy on the back of the Supplemental Data Sheet looks the most like the result of this simulated near miss? 3 (A. and Toome) (AD Hale O 8
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