ACTIVE GALAXY Meaning and
Definition
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An active galaxy refers to a type of galaxy that exhibits unusually energetic phenomena, such as the release of massive amounts of energy across various parts of the electromagnetic spectrum. This energy emission is typically seen at the core or nucleus of the galaxy, and it outshines the remaining parts by a significant margin. Active galaxies are dynamic celestial structures that are not powered by regular stellar processes alone.
One prominent type of active galaxy is the active galactic nucleus (AGN). An AGN consists of a supermassive black hole at its center, surrounded by an accretion disk of gas and dust. As matter falls into the gravitational pull of the black hole, it heats up to extreme temperatures, causing intense brightness across all wavelengths. This phenomenon is known as quasar activity, giving rise to one of the brightest objects in the universe.
Active galaxies come in various forms, such as Seyfert galaxies, blazars, radio galaxies, and quasars. These galaxies often display high levels of energy release, indicating ongoing interactions and mergers between galaxies, as well as the presence of powerful magnetic fields and jets of particles moving at near-light speeds.
Studying active galaxies provides insights into the processes occurring near supermassive black holes, the evolution of galaxies, and the formation and behavior of energetic cosmic phenomena.
Etymology of ACTIVE GALAXY
The term "active galaxy" is derived from the combination of two words: "active" and "galaxy".
The word "active" comes from the Latin word "activus", which means "doing, performing, or energizing". In English, the term refers to something that is engaged in action or actively participating in an activity or process.
The term "galaxy" has its roots in the Greek word "galaxias kyklos", which means "milky circle". It refers to a vast system of stars, gas, dust, and other celestial objects held together by gravitational forces. The term "galaxy" was later adopted in Latin as "galaxia" and then transferred into English.
When combined, the term "active galaxy" refers to a type of galaxy that exhibits strong and often violent activities, such as the emission of significant amounts of energy across different wavelengths.
