The article seemed to be pretty vague about the study itself, it said that they tracked 28 stars over the span of 16 years and that this proved that their was a black hole at the center of the milky way. I'm going to to assume that that means that the paths of the stars indicated an outside force was "pulling" on them.
Is this the case or can someone enlighten me, also if someone else has addressed this, my bad, but I didn't see a post about it. I'm new here so you'll have to bear with me, interesting stuff though. I think I'll end up doing some research later on, I'm a bit ignorant on the subject.