Measuring Galactic Rotation: How & What We Know

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In summary, we are able to measure galactic rotation by observing the velocity of stars in a galaxy and their distance from the center. These observations have shown that the velocities are faster than expected, leading to the use of dark matter to explain it. We look at both our own galaxy and other galaxies to gather evidence. This can be measured through the redshift of emission or absorption lines from gas. The research on galactic rotation has been ongoing for almost 90 years and has been done on thousands of galaxies. While there may be some errors in the measurements, the overall findings are considered reliable. A helpful link for further information is provided.
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PhDnotForMe
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TL;DR Summary
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.
 
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It can be measaured by using the redshift of the emission or the absorption lines that is coming from the gas.
PhDnotForMe said:
Summary: How we measure galactic rotation

Do we look at our own galaxy or do we look at other galaxies?
We do both ?
PhDnotForMe said:
Summary: How we measure galactic rotation

How are we so sure?
Why shouldn't we ?
 
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Arman777 said:
Why shouldn't we ?
Why should we ? -_-
 
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Arman777 said:
It can be measaured by using the redshift of the emission or the absorption lines that is coming from the gas.

Nice
 
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PhDnotForMe said:
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
PhDnotForMe said:
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 ?
 
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Arman777 said:
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:)
 
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1. How do scientists measure galactic rotation?

Scientists use a variety of methods to measure galactic rotation, including observing the Doppler shifts of stars and gas clouds, studying the distribution of mass within the galaxy, and analyzing the rotation curves of galaxies.

2. What is the rotation curve of a galaxy?

The rotation curve of a galaxy is a graph that shows how the rotational velocity of stars and gas clouds changes as a function of distance from the center of the galaxy. This curve can reveal information about the distribution of mass within the galaxy and the presence of dark matter.

3. How do scientists determine the mass of a galaxy?

Scientists use a combination of methods to determine the mass of a galaxy, including studying the rotation curves, observing the motion of stars and gas clouds, and analyzing the gravitational lensing effects caused by the galaxy.

4. What is dark matter and why is it important in measuring galactic rotation?

Dark matter is a type of matter that does not emit or absorb light, making it invisible to traditional telescopes. However, it exerts a gravitational pull on visible matter, affecting the rotation of galaxies. Understanding dark matter is crucial in accurately measuring galactic rotation and understanding the structure of the universe.

5. What are some current challenges in measuring galactic rotation?

One of the main challenges in measuring galactic rotation is the presence of dark matter, which makes up a significant portion of a galaxy's mass but cannot be directly observed. Scientists are also working to improve the accuracy and resolution of their measurements, as well as developing new techniques to study galactic rotation.

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