NGC 3521
NGC 3521, also known as the Bubble Galaxy, is a flocculent intermediate spiral galaxy located in the constellation Leo. Its velocity with respect to the cosmic [microwave background] is 1167 ± 26km/s, which corresponds to a Hubble distance of. However, 26 non-redshift measurements give a much closer distance of. It was discovered by German-British astronomer William Herschel on 22 February 1784.
NGC 3521 has a morphological classification of SABbc, which indicates that it is a spiral galaxy with a trace of a bar structure, a weak inner ring, and moderate to loosely wound arm structure. The bar structure is difficult to discern, both because it has a low ellipticity and the galaxy is at a high inclination of 72.7° to the line of sight. The relatively bright bulge is nearly 3/4 the size of the bar, which may indicate the former is quite massive. The nucleus of this galaxy is classified as an HII LINER, as there is an H II region at the core and the nucleus forms a low-ionization nuclear emission-line region.
NGC 3521 is structurally similar to the Milky Way; additionally, its supermassive [black hole] has a similar mass to that of the Milky Way, at about 7 million solar masses.