Measuring Galactic Rotation: How & What We Know

[PhDnotForMe]

TL;DR

How we measure galactic rotation

How have we been able to measure galactic rotation? I have seen graphs showing the relation between the velocity of stars in a galaxy and their distance from the center. These graphs show that the observed velocities of stars are much faster than they are expected to be, particularly ones that are farther from the center and they use dark matter to explain it. Do we look at our own galaxy or do we look at other galaxies? How are we so sure? Any links would be greatly appreciated.

 

[Arman777]

It can be measaured by using the redshift of the emission or the absorption lines that is coming from the gas.

Summary: How we measure galactic rotation

Do we look at our own galaxy or do we look at other galaxies?

We do both ?

Summary: How we measure galactic rotation

How are we so sure?

Why shouldn't we ?

 

[PhDnotForMe]

Why shouldn't we ?

Why should we ? -_-

 

[PhDnotForMe]

It can be measaured by using the redshift of the emission or the absorption lines that is coming from the gas.

Nice

 

[Arman777]

Nice

I find this nice site that explains it in more detail
http://www.astronomy.com/magazine/ask-astro/2018/05/rotational-speed-of-a-galaxy

Why should we ? -_-

There are always some errors in these measurements but this research is done for almost 90 years and for thousands of galaxies.

Do you have any opinion about what could be wrong with these measurements ?

 

[PhDnotForMe]

I find this nice site that explains it in more detail
http://www.astronomy.com/magazine/ask-astro/2018/05/rotational-speed-of-a-galaxyThere are always some errors in these measurements but this research is done for almost 90 years and for thousands of galaxies.

Do you have any opinion about what could be wrong with these measurements ?

Nope, was just curious on the actual method. Thanks for the link! You've been helpful:)