Measuring Galactic Rotation: How & What We Know

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Discussion Overview

The discussion centers on the methods used to measure galactic rotation, exploring both the techniques employed and the reliability of the data obtained. Participants inquire about the application of these methods to our galaxy versus other galaxies and express curiosity about the certainty of the findings, particularly in relation to dark matter explanations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes that galactic rotation can be measured using the redshift of emission or absorption lines from gas.
  • Another participant questions the certainty of the measurements, asking why we should trust them.
  • There is a suggestion that both our galaxy and other galaxies are studied in measuring galactic rotation.
  • Concerns are raised about potential errors in the measurements, with a participant mentioning that this research has been ongoing for nearly 90 years across thousands of galaxies.
  • A participant expresses curiosity about what could be wrong with the measurements but does not provide specific opinions.

Areas of Agreement / Disagreement

The discussion reflects a mix of curiosity and skepticism regarding the methods and reliability of galactic rotation measurements. While some participants provide information and resources, there is no clear consensus on the certainty of the measurements or the implications of potential errors.

Contextual Notes

Participants acknowledge the existence of errors in measurements but do not elaborate on specific assumptions or limitations that might affect the findings.

PhDnotForMe
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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.
 
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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 ? -_-
 
Arman777 said:
It can be measaured by using the redshift of the emission or the absorption lines that is coming from the gas.

Nice
 
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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