I noticed that the headline describes him as an “EMPLOYEE” of Duke University, like they were hiding the fact that he was a prof.
I don't believe he was a professor, which is a coveted title on a college or university campus which usually indicates that you hold a PhD as well as a tenured teaching position. And, depending on the campus, you may additionally have to meet other somewhat esoteric criteria before claiming the title of "professor".
Obama is frequently mischaracterized as a former professor of constitutional law. When in fact, he was just a lecturer with a class or two.