BL Lac object
From Free net encyclopedia
A BL Lac object or BL Lacertae object or BL Lac is a type of galaxy with an active galactic nucleus (AGN), making it a type of active galaxy. BL Lacs are based on the prototype BL Lacertae galaxy, which is highly variable. Their class is named like a star because BL Lacertae was originally thought to be a variable star. BL Lacs are classified as a subtype of blazar, the most energetic type of active galaxy.