黒い星 /ku roi ho shi/ would be the translation. As a title/name, ブラックスター /bu ra-kku su taa/ would be the Japanese spelling (like the character from Soul Eater manga/anime series).
'Hoshi.'
hikaru
its kuro
kuroikokoro
Kurotsuki
Kokushibyou
kokuchou
kuroji
kuroari
if you mean shooting star its nagare boshi
Kuroi sora is black sky.
Kuro Aisu=Black Ice