Visible distance of stars

["Paul Barufaldi"]

Working on a story.  Just wondering if anyone in this group can answer
a question for me (or refer me a URL that explains it)

I'd like to know how far away a star can be and remain visible in the
Earth's night sky (to the naked eye).  That is to say, what is the
most distant star visible on a clear night and how many light years
away is it?  What about star with the same luminosity as our Sun: from
what distance could that be seen?