How many stars are in the Milky Way galaxy?

  • Thread starter Thread starter mark96
  • Start date Start date
  • Tags Tags
    Star
Click For Summary

Homework Help Overview

The discussion revolves around estimating the number of stars in the Milky Way galaxy based on the orbital characteristics of a star. The problem involves concepts from astrophysics and gravitational dynamics.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss calculating the volume of a sphere to estimate the number of stars, while others suggest finding the mass of the central object based on the star's orbit. There are also mentions of using Gauss's law to determine the mass enclosed by the sphere.

Discussion Status

The discussion is ongoing, with various approaches being explored. Some participants have pointed out potential errors in the problem's parameters, and there is a mix of ideas regarding the methods to apply for solving the problem.

Contextual Notes

Participants note discrepancies in the provided values for mass, distance, and time, which may affect the calculations. The nature of the problem suggests it may be intended for a university-level audience.

mark96
Messages
3
Reaction score
0
Pllllease help me I have been stuck on this for ages:

[HRW5 14-57E] A star, with mass 3.29 1030 kg, revolves about the center of the Milky Way galaxy, which is 3.33 1020 m away, once every 2.17 108 years. Assuming that each of the stars in the galaxy has a mass equal to that of our star, that the stars are distributed uniformly in a sphere about the galactic center, and that our star is essentially at the edge of that sphere, estimate roughly the number of stars in the galaxy.

Answer needed ASAP
(working out would also be nice)
Thanks
 
Physics news on Phys.org
What have you tried so far?
 
Here's what I think, find the volume of the star sphere. Then divide that by the mass of the star.
 
Ive noticed a mistake in the question by the way. Where it says 3.29 1030kg, 3.33 1020m and 2.17 108 years it is supposed to say 3.39 x 10^30 kg, 3.33 x 10^20 m and 2.17 x 10^8.

Keep trying please

I think this may be a uni type of question.
 
You need to find the mass of the object that the star is orbiting such that it orbits at that speed at that distance. you can then divide that by the mass of your star to find how many stars
 
i think you would need Gauss's law. find out the acceleration of the star, then apply gauss's law to find out the mass enclosed by that sphere.
 

Similar threads

High School Are the stars that we see in constellations within the Milky Way galaxy?
  • · Replies 31 ·
2
Replies
31
Views
5K
High School Questions about Supermassive stars in the Milky Way Galaxy
  • · Replies 6 ·
Replies
6
Views
3K
Initial Mass Function Question (white dwarfs, neutron stars and black holes)
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Any Galaxy (Milky-way) based coordinate systems?
  • · Replies 8 ·
Replies
8
Views
3K
Undergrad Inquiry Regarding the Determination of the Galactic Disk's Outer Bound
  • · Replies 6 ·
Replies
6
Views
2K
Kapteyn's and Shapley's Milky Way - a comparison
  • · Replies 2 ·
Replies
2
Views
4K
High School Neutron star 4U 1820-30 spins at 716 revolutions per second
  • · Replies 0 ·
Replies
0
Views
3K
High School Our Sun's position in the Milky Way Galaxy
  • · Replies 2 ·
Replies
2
Views
6K
High School How does the Milky Way galaxy move in the local Group?
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad How to find the distance from a star to the center of the Milky Way Galaxy?
  • · Replies 8 ·
Replies
8
Views
5K