BL Lac object is a term used in astrophysics and astronomy to describe a type of active galactic nucleus (AGN). These objects are known for their variable and intense emission of radiation, particularly in the radio and X-ray wavelengths. In this article, we will explore the meaning and definition of BL Lac object, its origin, and its associations. We will also look at the synonyms, antonyms, and example sentences to help understand the term better.
Definitions
BL Lac object is a type of AGN that is characterized by a lack of strong emission lines in its spectrum. This makes it difficult to determine the redshift of the object and its distance from Earth. BL Lac objects are also known for their rapid variability, which is caused by the emission of synchrotron radiation from high-energy electrons in the jet of material that is ejected from the AGN.
Origin
The name BL Lac object comes from the first object of this type that was discovered in 1968, BL Lacertae. This object was named after the constellation Lacerta, where it was located in the sky. Since then, many more objects of this type have been discovered, and they are now collectively known as BL Lac objects.
Meaning in different dictionaries
BL Lac object is not a term that is commonly found in general dictionaries. However, it is defined in specialized dictionaries of astronomy and astrophysics. According to the Oxford Dictionary of Astronomy, BL Lac object is “a type of active galaxy that emits strongly in the radio and X-ray regions of the spectrum, and shows rapid and large-amplitude variations in brightness.” The McGraw-Hill Dictionary of Scientific and Technical Terms defines it as “a type of active galactic nucleus that lacks strong emission lines in its spectrum.”
Associations
BL Lac objects are associated with a class of AGN known as blazars. Blazars are AGN that have a relativistic jet pointed directly at Earth, which makes them appear much brighter and more variable than other types of AGN. BL Lac objects are a subset of blazars that have particularly weak emission lines in their spectra.
Synonyms
There are no commonly used synonyms for BL Lac object, as it is a specific term that describes a particular type of AGN. However, it may be referred to simply as a blazar or an active galactic nucleus in some contexts.
Antonyms
There are no antonyms for BL Lac object, as it is a specific term that describes a particular type of AGN.
The same root words
The term BL Lac object is named after the first object of this type that was discovered, BL Lacertae. The name Lacertae comes from the Latin word for lizard, which is the name of the constellation where the object was located. The BL in BL Lac object stands for the constellation’s name, while Lac refers to Lacertae.
Example Sentences
- BL Lac objects are known for their intense and variable emission of radiation.
- The lack of strong emission lines in the spectra of BL Lac objects makes it difficult to determine their distance from Earth.
- Blazars, including BL Lac objects, are a type of AGN that have a relativistic jet pointed directly at Earth.
- The discovery of BL Lacertae in 1968 led to the identification of many more objects of this type.
- Astronomers use the emission of synchrotron radiation from high-energy electrons in the jet of a BL Lac object to study the object’s properties.