I graduated with my Master's degree in Computer Science a couple of years ago. For a graduate requirement, I had to take on a project of significant scope and write a paper about the project. I had continued my project after graduation in order to attempt to publish a paper. This unfortunately did not happen, as I entered the workforce and focused my time on my new employment.
I received an email from my professor a couple of days ago asking if I had a copy of the source code to my project, because he has a new student who he wants to take over the project. He noted that if he was able to publish a paper with the new student, that my name would be added to the paper.
The professor had asked if I wanted to participate in the project, I replied that I would be able to help work on it in hopes of upping the chances that we get the paper published.
Since I am putting in hours post-graduation: should I expect to be compensated for my further work on the project, should I expect that this work is strictly voluntary in order to get my name on a paper, or is compensation up to the professor in charge of the project?