Another idea is that they weren’t stars at all. The three bright points are within 10 arcseconds of each other. If they were three individual objects, then something must have triggered their brightening. Given the timespan of about 50 minutes, causality and the speed of light would require they were no more than 6 AU apart. This means they would have to be no more than 2 light-years away. They could have been Oort Cloud objects where some event caused them to brighten around the same time. Later observations couldn’t find them because they had since drifted on along their orbits.
I like this idea. There’s something shark in the water-ish about having three more planet(oids) in the solar system that we only caught a glimpse of for an hour in 1952. It reminds me of Melancholia.