The morphological class of NGC 5584 is SAB(rs)cd,[8] which indicates this spiral galaxy has an inner bar (SAB), an incomplete inner ring structure (rs), and loosely wound spiral arms (cd). It is flocculent in appearance with only a small nucleus. Star formation is occurring along the spiral arms.[8] The galactic plane is inclined at an angle of 42.4° to the line of sight from the Earth,[7] and it spans more than 50,000 light-years across.[12] 250 Cepheid variables have been observed in NGC 5584.[1]
Two supernova events have been observed in NGC 5584. SN 1996aq was a Type Ic supernova discovered August 17, 1996 by Masakatsu Aoki in Japan. It was offset by 15″ west and 8″ south of the galactic center. It reached magnitude 14.7 on August 18.[13]SN 2007af was spotted at magnitude 15.4 on February 24, 2007 by K. Itagaki, also of Japan. This was a Type Ia supernova at an offset 40″ west and 22″ of the galaxy center.[14] A light echo of this event was observed about 1,000 days after its discovery.[15]
^Nakano, S.; et al. (August 1996). Green, D. W. E. (ed.). "Supernova 1996aq in NGC 5584". IAU Circular. 6454 (1): 1. Bibcode:1996IAUC.6454....1N.
^Hurst, G. M. (October 2007). "Supernova 2007af in NGC 5584". Journal of the British Astronomical Association. 117 (5): 280–281. Bibcode:2007JBAA..117..280H.
^Drozdov, Dina; Leising, M. D.; Milne, P.; Riess, A. G. (June 2013). "The Detection of a Light Echo from Type Ia SN 2007af in NGC 5584". American Astronomical Society, AAS Meeting #222. 222. Bibcode:2013AAS...22211804D. 118.04.