太郎が今ヨーロッパに行っている。 ‘Taro is now in Europe (as a result of having gone there).’
太郎が去年ヨーロッパに行っている。 ‘Taro is the one who has the experience of having gone to Europe last year.’
Can the latter mean the same as the former saying he went to Europe and has stayed there since?
What makes the latter different in meaning while both say ヨーロッパに行っている? Is it because of 今 and 去年？
What if both sentences have no indication of when it happened? That is 太郎がヨーロッパに行っている? What could this mean?