Please help! How to tell the difference between "backround" with megering
I have a question: When I see two galaxy in one picture and they are close, how can I tell one is megering with another or just one is backround of another?
(with no tidal debris)
Thank you for your replying!
by ElisabethB moderator
For me, it is a merger if I see a definite distortion in at least one of the galaxies.
Remember, here we classify only on sight.
If you have access to the redshifts (which we don't, prior to classification) that can give you a clue too.
But in GZ, the best indication is distortion.
Happy hunting !