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Antlia Cluster
The Antlia Cluster (or Abell S0636) is a cluster of galaxies located in the Hydra–Centaurus Supercluster. The Antlia Cluster is the third-nearest to the Local Group after the Virgo Cluster and Fornax Cluster. Antlia's distance from Earth is to and can be viewed from Earth in the constellation Antlia. The Antlia Cluster should not be confused with the Antlia Dwarf galaxy. Antlia is classified as a rare '' Bautz–Morgan type III'' cluster, meaning it has no central dominant (cD) brightest cluster galaxy. However, the cluster is dominated by two massive elliptical galaxies, NGC 3268 and NGC 3258, and contains a total of about 234 galaxies. The cluster is very dense compared to other clusters such as Virgo and Fornax, thus containing early-type galaxies and a larger portion of dwarf ellipticals. The cluster is split into two galaxy groups, ''the Northern subgroup'' gravitating around NGC 3268, and ''the Southern subgroup'' centered on NGC 3258. The cluster has an overall reds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epoch (astronomy)
In astronomy, an epoch or reference epoch is a instant, moment in time used as a reference point for some time-varying astronomical quantity. It is useful for the celestial coordinates or orbital elements of a Astronomical object, celestial body, as they are subject to Perturbation (astronomy), perturbations and vary with time. These time-varying astronomical quantities might include, for example, the mean longitude or mean anomaly of a body, the node of its orbit relative to a reference plane, the direction of the apogee or Perihelion and aphelion, aphelion of its orbit, or the size of the major axis of its orbit. The main use of astronomical quantities specified in this way is to calculate other relevant parameters of motion, in order to predict future positions and velocities. The applied tools of the disciplines of celestial mechanics or its subfield orbital mechanics (for predicting orbital paths and positions for bodies in motion under the gravitational effects of other bodi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |