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The Sun rotates around the center of the Milky Way Galaxy (Fig. 5–46) at a distance of
Chapter 5, Problem 88GP(choose chapter or problem)
The Sun rotates around the center of the Milky Way Galaxy (Fig. 5-46) at a distance of about 30,000 light-years from the center . If it takes about 200 million years to make one rotation, estimate the mass of our Galaxy. Assume that the mass distribution of our Galaxy is concentrated mostly in a central uniform sphere. If all the stars had about the mass of our Sun , how many stars would there be in our Galaxy?
Figure 5-46 Problem 88. Edge -on view of our Galaxy
Questions & Answers
QUESTION:
The Sun rotates around the center of the Milky Way Galaxy (Fig. 5-46) at a distance of about 30,000 light-years from the center . If it takes about 200 million years to make one rotation, estimate the mass of our Galaxy. Assume that the mass distribution of our Galaxy is concentrated mostly in a central uniform sphere. If all the stars had about the mass of our Sun , how many stars would there be in our Galaxy?
Figure 5-46 Problem 88. Edge -on view of our Galaxy
ANSWER:Solution 88 GP
Step 1 of 3
We have to estimate the mass of the Milky Way Galaxy.
The mass of the Milky Way Galaxy can be estimated by using the expressions for rotational speed (orbital velocity) of the Sun about the galactic centre.
where,
Universal gravitational constant
Nm2/kg2
radius of the Sun’s orbit around the
galactic centre = 30,000 light years
Thus,