Messier 59

Lore & Background

Messier 59 was discovered by Johann Gottfried Koehler in April 1779 while observing a comet that seemed close by. Charles Messier listed it in the Messier Catalogue about three days after Koehler's discovery. It is an elliptical galaxy of type E5 with a position angle of 163.3°, indicating a flattening of 50%. However, its isophotes deviate from perfect ellipticity, showing pointed shapes. These can be decomposed into a three-component model: a main elliptical part (62% of luminosity), a flatter disk-like feature, and a circular halo (22% of luminosity). The light ratio of the disk to the main elliptical body is 0.25, lower than the typical 0.5 in lenticular galaxies.

The core contains a supermassive black hole with an estimated mass of 270 million solar masses, which counter-rotates relative to the rest of the galaxy and is bluer. The black hole is quiescent but detectable as an X-ray and radio source indicating an outflow. The nucleus contains an embedded stellar disk that is bluer (younger) than the bulge, with a blue component stretching along a position angle of around 150°. This extended disk feature may result from a galactic merger followed by a starburst event.

Messier 59 is very rich in globular clusters, with an estimated population of about 2,200. It has two satellites: the ultra compact dwarf galaxy M59-UCD3 and M59cO, a rare example of a galaxy between compact ellipticals and ultra compact dwarfs. One supernova has been recorded: SN 1939B (Type Ia, mag. 15), discovered by Fritz Zwicky on 19 May 1939, reaching a peak magnitude of 11.9. The region shows no trace of star formation, consistent with a Type Ia supernova.

Reader's Guide

Messier 59 is significant as an elliptical galaxy that challenges simple classification due to its complex structure, including a disk-like component and a circular halo. Its supermassive black hole, which counter-rotates and is bluer than the galaxy, provides insight into galaxy mergers and black hole dynamics. The galaxy's rich globular cluster population (about 2,200) and its two satellite galaxies, including the rare M59cO, make it a valuable target for studying galaxy formation and evolution. The detection of a Type Ia supernova (SN 1939B) in a region with no star formation reinforces the standard model for such supernovae. Its legacy lies in its role as a nearby example of an elliptical galaxy with unusual internal motions and structure, contributing to understanding of how galaxies assemble and evolve within the Virgo Cluster.

Did You Know?

• Its supermassive black hole has an estimated mass of 270 million solar masses and counter-rotates relative to the galaxy.
• The galaxy has about 2,200 globular clusters and two satellite galaxies, including the rare M59cO.
• Only one supernova has been recorded in M59: SN 1939B, a Type Ia discovered by Fritz Zwicky.