Fornax Cluster
Second richest galaxy cluster within 100 million light-years after Virgo.
The Fornax Cluster, a grouping of galaxies, sits 19 megaparsecs (62 million light-years) away. Only the much larger Virgo Cluster outranks it in richness among clusters within 100 million light-years. Spanning roughly 6 degrees (about 28 square degrees) of sky, it mostly occupies the constellation Fornax, with its southern edge dipping into Eridanus. It may be linked to the nearby Eridanus Group.
Because it lies relatively close to the Sun, the Fornax Cluster offers valuable insights into how such clusters evolve. The gravitational effects of a merging galaxy subgroup with the main group are visible here, providing clues about the larger galactic superstructure. At its core sits NGC 1399. Other notable members include NGC 1316 (the cluster’s brightest galaxy), NGC 1365, NGC 1427A, NGC 1427, and NGC 1404.
The cluster splits into two subclusters. The main one centers on NGC 1399, while a subgroup about 3 degrees to the southwest, centered on the lenticular galaxy NGC 1316, is currently falling in to merge with it. Galaxies in this subgroup show relatively strong star formation.
Like many galaxy clusters, Fornax contains a hot, thin gas that emits X-rays, filling its intracluster medium. It also hosts a number of intergalactic stars, some of which have produced novae.
- Distance
- 19 megaparsecs (62 million light-years)
- Angular size
- about 6° across or about 28 square degrees
- Constellation
- Fornax (partially Eridanus)
- Central galaxy
- NGC 1399
- Brightest galaxy
- NGC 1316
- Notable members
- NGC 1365, NGC 1427A, NGC 1427, NGC 1404
Lore & Background
The Fornax Cluster can be divided into two subclusters: the main cluster centered on NGC 1399, and a subgroup 3 degrees to the southwest centered on the lenticular galaxy NGC 1316. This subgroup is currently in the process of infalling with the largest subcluster to merge with it, and its galaxies are experiencing relatively strong star formation activity. The cluster shows the gravitational effects of a merger of a galaxy subgroup with the main galaxy group, lending clues about the associated galactic superstructure.
As with many other galaxy clusters, the Fornax intracluster medium is filled with a hot, rarefied gas that emits X-rays and contains a number of intergalactic stars, some of which have produced novae. The cluster may be associated with the nearby Eridanus Group.
Reader's Guide
The Fornax Cluster is a particularly valuable source of information about the evolution of galaxy clusters due to its relatively close proximity to the Sun. Its structure reveals an ongoing merger process: a subgroup centered on NGC 1316 is infalling and merging with the main subcluster centered on NGC 1399. This merger provides observable gravitational effects that offer clues about the associated galactic superstructure. The cluster's intracluster medium, filled with hot X-ray-emitting gas and intergalactic stars that have produced novae, contributes to understanding the dynamics and evolution of such environments. As the second richest cluster within 100 million light-years, it serves as a key comparative object to the Virgo Cluster, helping astronomers study cluster formation and evolution at a relatively nearby distance.
Did You Know?
- The Fornax Cluster is the second richest galaxy cluster within 100 million light-years, after the Virgo Cluster.
- The cluster's intracluster medium contains intergalactic stars that have produced novae.
- A subgroup centered on NGC 1316 is currently infalling and merging with the main subcluster.
More in Galaxy Clusters and Groups, Part 4 1-24
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