Without the element of attraction, I think that we would just say that a person was a "fangirl" or "fanboy". That is someone who is emotionally invested in their fandom for a certain star. Sometimes people become an "Obsessed fan", they are the ones who get a little crazy.

Thank for your answers... then what is the expression for the "love" for a celebrity. something as "amor platonico" in spanish

The phrase is usually "to have a crush on" someone. Like "I have a crush on Jimmy Fallon". It doesn't have to do with celebrity and it is a very common phrase, especially among young people. Significa algo como infatuación. No es tan fuerte como amor.

You have the right idea, but it can be anybody not just a celebrity. Its particularly used during adolescence when you find someone attractive and fantasize about them... but it's not real love.