Learn German: Hieran müssen wir noch forschen. - We still need to do research on this.

Both translate to "on this" or "on it", but hieran is a proximate pronominal adverb. It points to something physically close or immediately present in the current conversation, like "this right here". The word daran is more neutral and often points to something previously mentioned, more like "on that".

Where does the -an in hieran come from?

It comes from the verb phrase forschen an (to research on / to do research on). When you want to say "research on this," you combine the prefix hier- with the required preposition an to create hieran.

Why is hieran in the first position of the sentence rather than wir?

Placing hieran at the very beginning emphasizes it. The speaker is stressing that on this specific topic, more research is needed. You could also say Wir müssen hieran noch forschen, but fronting the adverb makes the topic the focal point.

Could we use studieren instead of forschen here?

Not in this context. In German, studieren usually means to study a subject at a university (like majoring in physics) or to examine a document closely. The verb forschen specifically means to conduct scientific or academic research to discover new information.