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Andromeda 3
Andromeda III is a dwarf spheroidal galaxy about 2.44 million light-years away in the constellation Andromeda. It is part of the Local Group and is a satellite galaxy of the Andromeda Galaxy (M31). The galaxy was discovered by Sidney van den Bergh on photographic plates taken in 1970 and 1971. Observations of the dwarf galaxy using the WFPC2 in 2002 indicate that the bulk of the galaxy is around three billion years younger than the general population of globular clusters in our own galaxy. However, there are some older stars that are comparable in age to the Milky Way galactic clusters. There is no evidence for younger stars in this dwarf galaxy, suggesting no star formation is occurring. The dwarf galaxy is located at a distance of around from the center of M31. A total of 56 variable stars have been discovered in And III, including 51 RR Lyrae variables. See also * List of Andromeda's satellite galaxies The Andromeda Galaxy (M31) has satellite galaxies just like the Milky ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epoch (astronomy)
In astronomy, an epoch or reference epoch is a 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 celestial body, as they are subject to 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 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 bodies) can be used to generate an ephemeris, a table of values giving the posit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |