Why Is Galaxy NGC 221 Exhibiting a Blue Shift in Its Light Spectrum?

Earth. In summary, the light from galaxy NGC 221 is shifted towards shorter wavelengths, specifically the calcium "line" is observed at a wavelength of 396.58nm instead of 396.85nm. To determine the speed of the galaxy, use the formula fobs = fsourcesqrt[(c-v)/c+v)]. By plugging in the observed and expected frequencies, it can be determined that the galaxy is moving towards the Earth at a speed of v = -0.67c.
  • #1
Engineergirl2
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Homework Statement



The light from galaxy NGC 221 consists of a recognizable spectrum of wavelengths. However, all are shifted to the shorter wavelength end of the spectrum. In Particular, the calcium "line" ordinarily observed at 396.85nm is observed at 396.58nm. (a) is this galaxy moving towards or away from the earth? (b) at what speed?

Homework Equations



Fobs=fsourcesqrt(1-v^2/c^2)/(1+v/ccostheta)

The Attempt at a Solution


I think that the galaxy is moving toward the earth, but I'm not sure how to get what speed it's going at. I tried totake the ration of 396.58/396.85 to plug in so the frequencies would cancel out, but I'm getting a very small negative number. This doesn't seem right. Any help would be appreciated!
 
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  • #2
Use the formula
fobs = fsourcesqrt[(c-v)/c+v)]
 

Related to Why Is Galaxy NGC 221 Exhibiting a Blue Shift in Its Light Spectrum?

1. What is the Doppler Effect of light?

The Doppler Effect of light is a phenomenon in which the wavelength of light emitted from a moving source appears to change depending on the relative motion between the source and the observer. This effect is similar to the change in pitch of a siren as it approaches and then passes by an observer.

2. How does the Doppler Effect of light work?

The Doppler Effect of light works by changing the frequency and wavelength of light as the source of the light moves towards or away from the observer. When the source is moving towards the observer, the wavelength of the light appears shorter and the frequency appears higher. When the source is moving away from the observer, the wavelength appears longer and the frequency appears lower.

3. What causes the Doppler Effect of light?

The Doppler Effect of light is caused by the relative motion between the source of the light and the observer. This can occur with any type of light, including visible light, radio waves, and microwaves. The effect is also influenced by the speed of the source and the observer, as well as the distance between them.

4. How is the Doppler Effect of light used in science?

The Doppler Effect of light is used in various fields of science, including astronomy and physics. It is used to measure the speed and direction of celestial objects, such as stars and galaxies, as well as to study the expansion of the universe. It is also used in medical imaging, such as Doppler ultrasound, to measure the flow of blood in the body.

5. What are some real-life examples of the Doppler Effect of light?

One real-life example of the Doppler Effect of light is the redshift of light from distant galaxies. This is caused by the expansion of the universe, which causes the galaxies to move away from us, resulting in a longer wavelength and lower frequency of light. Another example is the blue or red shift of light from stars, which can indicate their speed and direction of motion towards or away from Earth.

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