Originally from Ireland, this all round compliment means you're a great person, you've risen to the occasion and been generally wonderful. It existed before the whole 'movie star' thing so it must relate more to a star in the sky.
Ah, thanks for bringing milk round for our cup of tea, sure you're a star!
Codeword for having sex later that evening/night in "socially unacceptable situations".
My lovely significant other and I were discussing afterlife sex and I proposed that what if new stars formed by gases were spiritually combined by orgasms and pretty much all the stars in the sky are couples in the afterlife glowing cause they're fucking. Surprisingly we weren't high..or at least, I wasn't. XD
"Hey babe, pass the salt? Only if we can make a star tonight." (;
*staring up at the night sky with your significant other*