M45 Pleiades

Pleiades, M45, or Seven Sisters, approx 440 light years from the Earth, is an open star cluster located in the constellation of Taurus. The Pleiades are at the moment passing through a cloud of interstellar medium, causing a blue glow around the stars.

Technical info:
TS 80mm f6 APO triplet refractor – Canon 40D – exposure (57x180sec) ~3 hours