娄宿三 (白羊座α / α Ari)俗称Hamal和El Nath，是白羊座的最亮星。它在弗兰斯蒂德命名法中是白羊座13，但因为其有拜耳命名法分类而极少使用。

娄宿三光谱型是K2IIICa-1，即它是一颗K型巨星，表面温度只有太阳的80%，但由于直径比太阳大上15倍，它仍然能发出太阳90倍的光芒。光谱型中的Ca表示它光谱中的钙线。依巴谷卫星（Hipparcos satellite）表明娄宿三距地球约66光年。由于其本身很亮，而且距离地球相对较近，使得其视亮度为2.00星等，是夜空中第47亮星。据称其亮度会少量波动约0.06星等。

Hamal (α Ari, α Arietis, Alpha Arietis) is the brightest star in the northern zodiacal constellation of Aries. It has the Bayer designation α Arietis and the Flamsteed designation of 13 Arietis. With an apparent visual magnitude of 2.0, it is among the brightest stars in the night sky. Based upon parallax measurements made with Hipparcos astrometry satellite, Hamal is about 65.8 light-years (20.2 parsecs) from Earth. It is a giant star that may host an orbiting planet with a mass greater than Jupiter.