Equatorial Mount for Nexstar 8SE

Hello everybody, I'm an armature astronomer/astrophotographer who owns a Celestron Nexstar 8SE. I've been very happy with the planetary and lunar images I have taken with its Alt-AZ mount and I'm interested in going to the next step of deep space astrophotography. I know that an ALT-AZ mount is not very good for deep space and would like to know what would be a good mount that is compatible with the nexstar 8se. I have also heard of something called a wedge and I'm not sure what that is.

I apologize for incorrect English, it is not my first language.

Thanks!