Japanese Language Stack Exchange is a question and answer site for students, teachers, and linguists wanting to discuss the finer points of the Japanese language. It only takes a minute to sign up.
Sign up to join this community
I will soon be visiting research laboratories in Japan and meeting with the professors in charge.
The english website clearly lists their position as "professor" and not "teacher".
Of course, the direct translation of professor is 教授, but I am uncertain whether 先生 would be a better (more natural) term to use when talking to them. As in X-先生 or X-教授 where X is the professor's last name.
When talking directly to your teachers, you can almost always stick to ～先生 and be safe, regardless of their positions (教授, 講師, 助教, ...). In general, ～教授 is used only when referring to them in the third person. This is in contrast to private companies, where 部長 can be called (X-)部長, etc.
But depending on the university you visit, there may be rare local rules. For example, in Keio University, all the teachers seem to be addressed using ～君 at least in formal ceremonies and official documents.
I cannot comment since I don't have 50pts but I am a Keio student and everybody use 先生の苗字-先生 and never 先生の苗字-君.
An advice: Don't ever use くん as a suffix. Use everytime 先生.
