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Galaxy X (galaxy)
Galaxy X is a postulated dark satellite dwarf galaxy of the Milky Way Galaxy. If it exists, it would be composed mostly of dark matter and interstellar gas with few stars. Its proposed location is some from the Sun, behind the disk of the Milky Way, and some in extent. Galactic coordinates would be (l= -27.4°,b=-1.08°). Discovery Observational evidence for this galaxy was presented in 2015, based on the claimed discovery of four Cepheid variable stars by Sukanya Chakrabarti (RIT) and collaborators. Search for the stars was motivated by an earlier study that linked a warp in the HI (atomic hydrogen) disk of the Milky Way Galaxy to the tidal effects of a perturbing galaxy. The unseen perturber's mass was calculated to be about 1%approximately 10 billion solar masses of that of the Milky Way, which would make it the third heaviest satellite of the Milky Way, after the Magellanic Clouds (Large Magellanic Cloud and Small Magellanic Cloud, each some 10x larger than Galaxy X ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dark Galaxy
A dark galaxy is a hypothesized galaxy with no, or very few, stars. They received their name because they have no visible stars, but may be detectable if they contain significant amounts of gas. Astronomers have long theorized the existence of dark galaxies, but there are no confirmed examples to date. Dark galaxies are distinct from intergalactic gas clouds caused by galactic tidal interactions, since these gas clouds do not contain dark matter, so they do not technically qualify as galaxies. Distinguishing between intergalactic gas clouds and galaxies is difficult; most candidate dark galaxies turn out to be tidal gas clouds. The best candidate dark galaxies to date include HI1225+01, AGC229385, and numerous gas clouds detected in studies of quasars. On 25 August 2016, astronomers reported that Dragonfly 44, an ultra diffuse galaxy (UDG) with the mass of the Milky Way galaxy, but with nearly no discernable stars or galactic structure, is made almost entirely of dark matter. Obse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |