How Do I Calculate Galactic Mass Proportional to Radius?

  • Thread starter Thread starter StephenPrivitera
  • Start date Start date
  • Tags Tags
    Mass Proportional
AI Thread Summary
To calculate galactic mass as a function of radius, the equations M(r)=v^2r/G and M(r)=vrc^2/G are discussed, with the first being the correct formula for calculating mass based on velocity and radius. The velocity, v, can be determined from the flat rotation curve by using the total mass and radius of the galaxy. For tidal force calculations, the derived formula r=(d^3m/(2MR))^1/2 is presented, where m is the mass of the galaxy containing the star, R is its radius, M is the mass of the nearby galaxy, and d is the distance between the galactic centers. Verification of these calculations is sought to ensure accuracy. Understanding these relationships is crucial for analyzing galactic dynamics and tidal interactions.
StephenPrivitera
Messages
360
Reaction score
0
How do I calculate galactic mass as a function of r? I know it is supposed to be proportional to r. I've seen,
M(r)=v2r/G
And also I've seen
M(r)=vrc2/G
Which if any is right?
And what do I use for v?
Thanks so much for your help!
 
Astronomy news on Phys.org
The rotation curve is flat so I can find v by plugging in the radius and total mass of the galaxy. Doing that I get,
M(r)=Mr/R, where M is the total mass of the galaxy and R is the radius of the galaxy
I'm trying to do a tidal force calculation to see how far away from the center of a galaxy a star needs to be to be tidally disrupted by a nearby galaxy. I'm getting
r=(d3m/(2MR))1/2 where m is the total mass of the galaxy that the star lies in, R is the radius of that galaxy, M is the total mass of the nearby galaxy, and d is the distance between the two galactic centers. Can anyone verify this?
 

Thread 'Does it make sense to build new radio telescopes?'

TL;DR Summary: In 3 years, the Square Kilometre Array (SKA) telescope (or rather, a system of telescopes) should be put into operation. In case of failure to detect alien signals, it will further expand the radius of the so-called silence (or rather, radio silence) of the Universe. Is there any sense in this or is blissful ignorance better? In 3 years, the Square Kilometre Array (SKA) telescope (or rather, a system of telescopes) should be put into operation. In case of failure to detect...
View full post »
Thread 'Could gamma-ray bursts have an intragalactic origin?'

Thread 'Could gamma-ray bursts have an intragalactic origin?'

This is indirectly evidenced by a map of the distribution of gamma-ray bursts in the night sky, made in the form of an elongated globe. And also the weakening of gamma radiation by the disk and the center of the Milky Way, which leads to anisotropy in the possibilities of observing gamma-ray bursts. My line of reasoning is as follows: 1. Gamma radiation should be absorbed to some extent by dust and other components of the interstellar medium. As a result, with an extragalactic origin, fewer...
View full post »

Thread 'Our Beautiful Universe - Photos and Videos'

This thread is dedicated to the beauty and awesomeness of our Universe. If you feel like it, please share video clips and photos (or nice animations) of space and objects in space in this thread. Your posts, clips and photos may by all means include scientific information; that does not make it less beautiful to me (n.b. the posts must of course comply with the PF guidelines, i.e. regarding science, only mainstream science is allowed, fringe/pseudoscience is not allowed). n.b. I start this...
View full post »

Similar threads

I Calculating Proportional Luminosity of Fictitious Star
Replies
11
Views
2K
A Interactive Galactic Dynamics Textbook -- Bovy 2022
Replies
2
Views
2K
B Relating Gravitational Field Strength and Mass
Replies
5
Views
2K
White dwarf mass-radius relationship
Replies
7
Views
6K
B Colliding Gas Cloud to form a Star
Replies
3
Views
987
I Orbital Velocities and Mass Distribution in Galaxies
Replies
7
Views
2K
I The proportion of kinetic energy of a rotating rigid body?
Replies
7
Views
1K
I Reframing Light Bending Using Density Instead of Radius
Replies
20
Views
554
Flat galaxy rotation curves without dark matter
Replies
1
Views
3K
I Measuring the rotation curve of galaxies
Replies
1
Views
2K

Hot Threads

Recent Insights

Back
Top