5-487: BL Lac may refer to: BL Lacertae , an active galaxy, prototype of the BL Lacertae objects BL Lacertae object , a type of active galaxy, based on the prototype BL Lacertae galaxy Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title BL Lac . If an internal link led you here, you may wish to change
10-523: A recession velocity of 21,000 km/s with respect to the Milky Way. The redshift figure implies that the object lies at a distance of 900 million light years. Due to its early discovery, BL Lacertae became the prototype and namesake of the class of active galactic nuclei known as " BL Lacertae objects " or "BL Lac objects". This class is distinguished by rapid and high-amplitude brightness variations and by optical spectra devoid (or nearly devoid) of
15-457: The broad emission lines characteristic of quasars . These characteristics are understood to result from relativistic beaming of emission from a jet of plasma ejected from the vicinity of a supermassive black hole . BL Lac objects are also categorized as a type of blazar . BL Lacertae changes in apparent magnitude over fairly small time periods, typically between values of 14 and 17. In January 2021, it exhibited extreme flaring behavior and
20-475: The link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=BL_Lac&oldid=1016944284 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages BL Lacertae BL Lacertae or BL Lac is a highly variable, extragalactic active galactic nucleus (AGN or active galaxy ). It
25-586: Was first discovered by Cuno Hoffmeister in 1929, but was originally thought to be an irregular variable star in the Milky Way galaxy and so was given a variable star designation . In 1968, the "star" was identified by John Schmitt at the David Dunlap Observatory as a bright, variable radio source . A faint trace of a host galaxy was also found. In 1974, Oke and Gunn measured the redshift of BL Lacertae as z = 0.07, corresponding to
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