What does the yellow asterisk symbol next to a torrent name mean?
I think it's related to torrents I've made?

it means that you made the torrent.

This happened to me because my PC crashed. I had a backup of all the torrent files but not the Tixati configs, so when I bought and populated a new PC all of my torrents were asterisked! I'm gradually finding most of them by searching the torrent sites I usually use. If you can download the right torrent, you can make sure it has a unique name and then copy all the completed files over the "new" torrent files.

A shame, though, that you can't edit the original torrent.