Who can explain to me how do u calculate distance of a star based on the redshift of receieved waves?


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  • I don't think you can calculate the "distance". You can calculate how quickly the star is moving away from us, by the redshift. Since the star is moving away, the emitted lightwave is being "stretched" out by the fact that the star is moving away. The stretched out lightwave shifts to the color red. Blueshift means the star is moving towards us. In that case, the light waves are compressed and the color shifts to blue.

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    • 3 d ago

      It was my understanding that the stretch in wavelength is caused by the amount of didtance light had to travel through space... higher distance traveled will shift to red more

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    • 2 d ago

      Yes the doppler effect also causes the red shift due to moving away source, but it can be also caused by the faster than speed of light continuous expansion of space. So basically the farther away the source is, it will pass through a greater amount of space to reach us. But what i dont know is how can that be used to measure distance of a star, we do need the source wavelength dont we.

    • 2 d ago

      Ah OK... Now that would take someone is who more knowledgable about astronomy than I...

  • I'm not the best person to explain it. But it's a combination of the the doppler effect, the emissions spectrum of stars, and the accelerating expansion of the universe. Shit further away, is moving at a faster speed so it's emissions spectrum is under a larger impact by the doppler effect.

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    • 3 d ago

      Yeah i get it higher the redshift farther the source.. but how do they know the wavelength when it was emitted by the source

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    • 1 d ago

      Right.. and that does not help with finding the distancr

    • 1 d ago

      Yes it does. Because the Doppler shift is a universal constant. You know which wavelengths of light should be absorbed, and you know which wavelengths are reaching Earth. From there it's just some simple calculations.

  • I don’t

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