I know how to use a favicon but I mean something else: There must be a way to use images in html title tags see this page as an example: http://helios.io/
How is this little rockets right of the title text added?
You cannot use images in a title, not in the traditional sense of JPG, PNG, GIF, etc.
The little rocket ship that you see is a text character that can be 'typed'. There are numerous little characters you can type that way.
However, I believe the rocket ship you see is a Mac / iOS only character... as it's an emoji rocket ship.