NGC 4393
Flocculent spiral galaxy in Coma Berenices with a nuclear star cluster.
NGC 4393 is a spiral galaxy around 46 million light-years from Earth, located in the constellation Coma Berenices. It belongs to the NGC 4274 Group, which is part of the larger Coma I Group or Cloud. William Herschel discovered it on April 11, 1785.
The galaxy has a flocculent spiral structure, meaning its arms are chaotic, fragmented, and not symmetric. Within it lies IC 3329, an HII region discovered by Max Wolf on March 23, 1903. Wolf described it as "very faint, small, irregular figure, attached to (NGC) 4393."
NGC 4393 contains a pseudo-bulge, a type of galactic bulge that resembles a disk galaxy more than a classical bulge. It has a flatter shape, a high ratio of ordered stellar motions over random ones, a small velocity dispersion relative to the Faber-Jackson relation, and may include a spiral structure or nuclear bar in its bulge. Its brightness profile is nearly exponential, and it can host starbursts.
At its center is a nuclear star cluster with a mass of 0.4048 ± 0.0819 million solar masses and a diameter of roughly 4.8 parsecs.
Quick Facts
- Epoch
- J2000
- Ra
- 12 · 25 · 51.2
- Dec
- 27 · 33 · 42
- Dist Ly
- 14.2 Mpc
- Group Cluster
- Coma I (NGC 4274 subgroup)
- H Radial V
- 751 km/s
- Z
- 0.002505
- Appmag V
- 12.7
- Constellation Name
- Coma Berenices
- Names
- UGC 07521, PGC 040600, MCG +05-29-083
Facts from the source article.
Lore & Background
NGC 4393 was discovered by astronomer William Herschel on April 11, 1785. It is a flocculent spiral galaxy, characterized by chaotic, fragmented, and unsymmetric arms. Within it lies IC 3329, an HII region discovered by astronomer Max Wolf on March 23, 1903, described as 'very faint, small, irregular figure, attached to (NGC) 4393'.
The galaxy hosts a pseudo-bulge, a type of galactic bulge that resembles a disk galaxy more than a classical bulge. This pseudo-bulge exhibits flatter shapes, large ratios of ordered stellar motions rather than random motions, small velocity dispersions relative to the Faber-Jackson correlation, a spiral structure or nuclear bar in the bulge light profile, nearly exponential brightness profiles, and starbursts.
The central region of NGC 4393 contains a nuclear star cluster with a mass of 0.4048 ± 0.0819 million solar masses and a diameter of approximately 4.8 parsecs.
Reader's Guide
NGC 4393's significance lies in its role as a member of the NGC 4274 Group within the larger Coma I Group or Cloud, contributing to the understanding of galaxy clustering in the local universe. Its flocculent spiral structure, with chaotic and fragmented arms, provides an example of a galaxy where star formation and spiral arm dynamics are irregular rather than well-defined. The presence of a pseudo-bulge, rather than a classical bulge, offers insight into the diversity of galactic bulge types and their evolutionary pathways, as pseudo-bulges share characteristics with disk galaxies such as ordered stellar motions and exponential brightness profiles. The nuclear star cluster at its center, with a precisely measured mass and diameter, serves as a valuable data point for studies of supermassive black hole formation and the relationship between nuclear clusters and their host galaxies. Additionally, the HII region IC 3329, discovered by Max Wolf, highlights the detailed substructure within NGC 4393 and the historical contributions of early 20th-century astronomers to extragalactic astronomy.
Did You Know?
- NGC 4393 is a flocculent spiral galaxy with chaotic, fragmented, and unsymmetric arms.
- It hosts a pseudo-bulge, which has characteristics more similar to disk galaxies than classical bulges.
- IC 3329, an HII region in NGC 4393, was discovered by Max Wolf and described as 'very faint, small, irregular figure, attached to (NGC) 4393'.
More in Galaxy Clusters and Groups, Part 4 1-24
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