The Sterope /ˈstɛrəpiː/ or Asterope /əˈstɛrəpiː/[1] system is a double star in the zodiac constellation of Taurus. Its components have the Flamsteed designations 21 Tauri and 22 Tauri,[2] and are sometimes known as Sterope I and Sterope II, respectively.[3]
The International Astronomical Union applies the name Asterope specifically to 21 Tauri.[4] The two stars are thus
The two stars are separated by 0.047° on the sky, which is equal to 2.82 arc-minutes and thus closer than the usual naked-eye resolution limit of 4 arc-min, giving an elongated appearance of the two together. Both are members of the Pleiades open star cluster (M45) and approximately 440 light-years from the Sun.