Junji
Jun5-11, 08:30 AM
Hi!
I want to estimate the distance and mass of a galaxy by given values.
The center of an inclined galaxy sends out light of a certain wavelength (f.ex. the HI line) out to a certain radius r.
At the outer edges of the galaxy the emitted line has a wavelength of l +/- dl
At first, I thought the distance is calculated by using the redshift principle. However, this would mean that one edge has a redshift whereas the other one has a blueshift, so the galaxy plane would be rotating. Can this be possible?
Yet, I don't know why else there are observed different wavelengths at the edges and why the center wavelength is observed out to a radius r. Any ideas?
If my first thought was right, I get to the following equation:
The formula for the redshift is given as c*z = H*d , with redshift z = dl/l and Hubble constant H.
So the distance for the more distance edge would be d = c*(dl/l)/H, right?
However, I don't have any ideas so far, how to estimate the mass of a galaxy.
Is there some relation between the emitted wavelengths and its mass at all?
Thank you in advance!
Junji
I want to estimate the distance and mass of a galaxy by given values.
The center of an inclined galaxy sends out light of a certain wavelength (f.ex. the HI line) out to a certain radius r.
At the outer edges of the galaxy the emitted line has a wavelength of l +/- dl
At first, I thought the distance is calculated by using the redshift principle. However, this would mean that one edge has a redshift whereas the other one has a blueshift, so the galaxy plane would be rotating. Can this be possible?
Yet, I don't know why else there are observed different wavelengths at the edges and why the center wavelength is observed out to a radius r. Any ideas?
If my first thought was right, I get to the following equation:
The formula for the redshift is given as c*z = H*d , with redshift z = dl/l and Hubble constant H.
So the distance for the more distance edge would be d = c*(dl/l)/H, right?
However, I don't have any ideas so far, how to estimate the mass of a galaxy.
Is there some relation between the emitted wavelengths and its mass at all?
Thank you in advance!
Junji