NGC 1365 is truly a giant of the sky. Located in the Fornax cluster of galaxies the symmetric spiral structure spans 200,000 light years across. Its size, rivaled only by M101, another giant spiral in the local universe, makes NGC 1365 a true supergiant galaxy. NGC 1365 is a prototypical barred galaxy with an active galactic nucleus (AGN) belonging to the subclass of Seyfert galaxies. Galaxies with AGN properties exhibit copious energy release from their nuclear regions from a nonstellar source. The energy source is believed to be a rotating accretion disk losing matter to a massive black hole at the galaxy's center. Seyfert galaxies constitute the largest group of galaxies hosting an AGN and are characterized by a bright point source of light that can at times outshine the entire parent galaxy. The point source within the nucleus of NGC 1365 is less than 10 light years across but is obscured optically by thick dustlanes that penetrate into the nuclear region. Seyferts are further subdivided into type I and II (NGC 1365 is type II) by their emission lines. Typical of galaxies with an AGN, a bi-directional jet of superheated plasma is being expelled from the nuclear region at relativistic speeds. The jets have been detected at both radio and x-ray wavelengths.
The nature of unseen dark matter within the halos of galaxies is one of the most important problems in astronomy today. Dark matter must exist to explain the lack of fall off in the rotation velocity of disk components far from the galaxy's center. Without the existence of dark matter the galaxy would become unstable and its structure would breakdown. NGC 1365 shows a fairly steep fall off in its rotation curve suggesting it may lack a massive dark matter halo. Astronomers believe that the lack of such a halo may be conducive to the formation of a particularly strong bar which is consistent with what we see in NGC 1365. Also related to the strong bar is the presence of several nuclear "hot spots" in the center of the galaxy. Some of these represent young superclusters of massive stars. Gas inflow towards the circumnuclear region incites star formation and is heavily influenced by the presence of a strong bar at the center of the galaxy. The torque forces of the bar create preferred resonance rings where redistribution of disk matter occurs. Star formation tends to occur within these rings.