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Ursa Major Dwarf (other)
Ursa Major Dwarf is a name for two dwarf spheroidal galaxies orbiting the Milky Way Galaxy The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galaxy, which are .... * Ursa Major I Dwarf, also called UMa I dSph, was discovered in 2005. * Ursa Major II Dwarf, also called UMa I, dSph, was discovered in 2006. See also * Palomar 4, once thought to be a satellite galaxy, now known to be a globular cluster of the Milky Way {{SIA Ursa Major ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dwarf Spheroidal Galaxy
A dwarf spheroidal galaxy (dSph) is a term in astronomy applied to small, low-luminosity galaxies with very little dust and an older stellar population. They are found in the Local Group as companions to the Milky Way and as systems that are companions to the Andromeda Galaxy (M31). While similar to dwarf elliptical galaxies in appearance and properties such as little to no gas or dust or recent star formation, they are approximately spheroidal in shape and generally have lower luminosity. Discovery Despite the radii of dSphs being much larger than those of globular clusters, they are much more difficult to find due to their low luminosities and surface brightnesses. Dwarf spheroidal galaxies have a large range of luminosities, and known dwarf spheroidal galaxies span several orders of magnitude of luminosity. Their luminosities are so low that Ursa Minor, Carina, and Draco, the known dwarf spheroidal galaxies with the lowest luminosities, have mass-to-light ratios (M/L) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Milky Way
The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the #Appearance, galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galaxy, which are so far away that they cannot be individually distinguished by the naked eye. The Milky Way is a barred spiral galaxy with a Galaxy#Isophotal diameter, D25 isophotal diameter estimated at , but only about 1,000 light-years thick at the spiral arms (more at the bulge). Recent simulations suggest that a dark matter area, also containing some visible stars, may extend up to a diameter of almost 2 million light-years (613 kpc). The Milky Way has several List of Milky Way's satellite galaxies, satellite galaxies and is part of the Local Group of galaxies, forming part of the Virgo Supercluster which is itself a component of the Laniakea Supercluster. It is estimated to contain 100–400 billion stars and at least that number of pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ursa Major I Dwarf
Ursa Major I Dwarf (UMa I dSph) is a dwarf spheroidal galaxy that orbits the Milky Way galaxy. It was discovered in 2005 within the Ursa Major constellation and is the third least luminous known galaxy. Discovery # It was discovered by Beth Willman, Julianne J. Dalcanton, David Martinez-Delgado, and Andrew A. West in 2005. Properties Being a small dwarf galaxy, it measures only a few thousand light-years in diameter. As of 2006, it is the third least luminous galaxy known (discounting possible dark galaxies such as VIRGOHI21 in the Virgo cluster of galaxies), after the Boötes Dwarf (absolute magnitude −5.7) and the more recently discovered Ursa Major II Dwarf (absolute magnitude −3.8). The absolute magnitude of the galaxy is estimated to be only −6.75, meaning that it is less luminous than some stars, like Deneb in the Milky Way. It is comparable in luminosity to Rigel. It has been described as similar to the Sextans Dwarf Galaxy. Both galaxies are ancient and met ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ursa Major II Dwarf
Ursa Major II Dwarf (UMa II dSph) is a dwarf spheroidal galaxy situated in the Ursa Major constellation and discovered in 2006 in the data obtained by the Sloan Digital Sky Survey. The galaxy is located approximately 30 kpc from the Sun and moves towards the Sun with the velocity of about 116 km/s. It has an elliptical (ratio of axes ~ 2:1) shape with the half-light radius of about 140 pc. Ursa Major II is one of the smallest and faintest satellites of the Milky Way—its integrated luminosity is about 4000 times that of the Sun (absolute visible magnitude of about −4.2), which is much lower than the luminosity of the majority of globular clusters. UMa II is even less luminous than some stars, like Canopus in the Milky Way. It is comparable in luminosity to Bellatrix in Orion. However, its mass is about 5 million solar masses, which means that the galaxy's mass to light ratio is around 2000. This may be an overestimate as the galaxy has a somewhat irregular sh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palomar 4
Palomar 4 is a globular cluster of the Milky Way galaxy belonging to the Palomar Globular Clusters group. It was discovered in 1949 by Edwin Hubble and again in 1955 by A. G. Wilson. It is calculated to be from the Sun. This star cluster is further away than the SagDEG satellite galaxy. Initially it was thought to be a dwarf galaxy A dwarf galaxy is a small galaxy composed of about 1000 up to several billion stars, as compared to the Milky Way's 200–400 billion stars. The Large Magellanic Cloud, which closely orbits the Milky Way and contains over 30 billion stars, is so ..., and it was given the name Ursa Major Dwarf. However, it was later discovered to be a globular cluster. See also * Ursa Major Dwarf References External links * * Palomar 04 Palomar 04 Palomar 04 Local Group UGCA objects {{star-cluster-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
