M77
Cetus A or Squid Galaxy
Spiral
Proprietà
Posizione e identificatori
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Su M77
Descrizione
M77 (also called Cetus A) is a barred spiral galaxy in Cetus, about 47 million light-years from Earth. It is one of the largest Messier galaxies, spanning about 170,000 light-years. M77 harbors one of the brightest and most active Seyfert nuclei known — its supermassive black hole (about 15 million solar masses) actively accretes material and powers intense radiation across the electromagnetic spectrum.
Consigli per l'osservazione
Located about 1 degree east-southeast of Delta Ceti. In a telescope it appears as a bright, round, concentrated glow dominated by the brilliant nucleus. The spiral arms have low surface brightness and require 10 inches or more to detect. The intense nuclear brightness makes it easy to spot but hard to see detail. Best observed from October through January.
Storia
Discovered by Pierre Mechain on October 29, 1780. Charles Messier cataloged it on December 17, 1780. It was one of the first galaxies identified as having an active nucleus — Carl Seyfert included it in his 1943 study of galaxies with unusually bright cores, which defined the class of Seyfert galaxies.
Curiosità
M77 is the brightest and nearest Seyfert galaxy — a class of galaxies with active galactic nuclei powered by supermassive black holes devouring surrounding material. The galaxy emits strongly in X-rays, infrared, and radio wavelengths. In 2022, the Very Large Telescope directly imaged the thick ring of dust surrounding M77's central black hole, confirming the unified model of active galactic nuclei.
Foto della comunità (1)
Credit: NASA, ESA & A. van der Hoeven. License: Public domain. (Wikimedia Commons)
Skybred Feb 28, 2026