In article ,
"Michael F. Stemper" writes:
However, I'm not sure what the term "z=0 galaxy" means. To me,
"z=0" means "zero redshift", or "right here".

Right. Specifically, it means galaxies so nearby that their
redshifts don't matter. That means the observed and emitted
wavelengths are effectively equal, and the lookback time is small
compared to any evolutionary timescale. Depending on what you are
trying to do, that could mean less than a few tens of megaparsecs to
z0.1 or even larger.

It probably wasn't an ideal term for an instructor to use without
clarification, but for the exercise "Characterize the star formation
history of z=0 satellite and central galaxies," you should be safe
out to Coma and maybe farther if the relevant data exist.

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