I will submit questions as an attachment Document Preview: 1.To what redshift/blueshift could we observe HI if our spectrometer covered a 64.00 MHz band centred on 1.410 GHz. [What velocities do...

Problem 1
It’s given that spectrometer covers a band of 64MHz and is entered it 1.410 GHz . To the maximum Shift in the
frequency that we can predict with the spectrometer is 64MHz .
We have the frequency band from
64 64
1.41GHz MHz 1.442GHz to 1.41GHz MHz 1.378GHz
2 2
   
So, so if we treat that the emitted frequency is 1.378 GHz then the observed frequency should be less than
1.442 GHz in order to predict by our spectroscope. This corresponds to the maximum red shift “z” .
which is given by o
e
1.442
z 1 1 0.0464 (redshift)
1.378

    


and the maximum blue shift is given by o
e
1.378
z 1 1 0.0443 (blueshift)
1.442

     


What velocities do these correspond to?
This maximum red shift corresponds to a velocity “v” given by
8 1 1
v z x c where cisspeed of light
0.0464x3x10 13920000ms 13920kms 

  

and the maximum blue shift corresponds to a velocity “v” given by
8 1 1
v z x c where cisspeed of light
0.0443x3x10 13290000ms 13290kms 

  

Problem 2
Doppler Shift
When a source of light is moving toward or away from an observer, the measured wavelength of the received
light (λobserved) will be different than the wavelength of the light if the source were at rest (λrest). The measured
wavelength of the observed light and the line-of-sight velocity (VLOS) of the source are related through the
Doppler equation:
los observed rest
rest
v
where cis speedof light
c
 


Rotation Velocity
The line-of-sight velocity (ie the point O, E, W in the figure ) that is calculated from the Doppler equation tells us
how fast the gas is moving directly toward or...