Suppose Hbeta absorption at 4861A is strong in all astronomical objects.  As a group, qualitatively predict the the observed spectra for the following scenarios.  A spectral slit laid across:

a single star that is not moving with respect to our Solar System.

a single star that is receding away from us.

a binary star system, with M1=10Msun, M2=1Msun.  The system is moving toward us.

a binary star system, with M1=100Msun, M2=1Msun.  The system is moving away from us.

the major axis of a spiral galaxy viewed face-on.

the major axis of a spiral galaxy viewed edge-on.

the minor axis of a spiral galaxy viewed edge-on.