出典:Wiktionary
出典:『Wiktionary』 (2025/05/08 12:52 UTC 版)
BL Lac object (plural BL Lac objects)
出典:Wikipedia
出典:『Wikipedia』 (2011/05/22 23:15 UTC 版)
A BL Lacertae object or BL Lac object is a type of active galaxy with an active galactic nucleus (AGN) and is named after its prototype, BL Lacertae. In contrast to other types of active galactic nuclei, BL Lacs are characterized by rapid and large-amplitude flux variability and significant optical polarization. Because of these properties, the prototype of the class (BL Lac) was originally believed to be a variable star. When compared to the more luminous active nuclei (quasars) with strong emission lines, BL Lac objects have spectra dominated by a featureless non-thermal continuum.