10 Lacertae

10 Lacertae (10 Lac) is a star in the constellation Lacerta. With an apparent magnitude is 4.9, it is located around 700 parsecs (2,300 ly) distant in the small Lacerta OB1 association. It is a hot blue main-sequence star of spectral type O9V, a massive star that is currently fusing its core hydrogen. It is a suspected Beta Cephei variable star.

10 Lacertae was one of the first O-type stars (along with S Monocerotis) to be defined as an anchor point for the MKK spectral classification; since the early twentieth century it has served as such a point. Specifically, the star is representative of O9V stars, meaning relatively cool O-type stars on the main-sequence.

10 Lacertae has an 8th magnitude companion about one arc-minute away.