Hello everyone. I am doing an studi on Be stars, all of which are inside the Milky Way, I want to show that the red shift won't be a big deal here, but I am confused about how to prove it; what I have done is combining the equations λr=λe(1+z) and cz=Hd to get λr=λe(1+Hd/c) where z=v/c. I get extremely minor changes in my red shift if I introduce the Galaxy's diametre in d, but I am not sure that aplying the equation cz=Hd is legitimate here or if it can only be used to measure distances between galaxies. Can someone please tell me if I am using a good methode to calculate the red shift? Thanks for reading.