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Wolf–Lundmark–Melotte
The Wolf–Lundmark–Melotte (WLM) is a barred irregular galaxy discovered in 1909 by Max Wolf, located on the outer edges of the Local Group. The discovery of the nature of the galaxy was accredited to Knut Lundmark and Philibert Jacques Melotte in 1926. It is in the constellation Cetus. Properties Wolf–Lundmark–Melotte is a rotating disk that is seen edge-on. It is relatively isolated from the rest of the Local Group, and does not seem to show much evidence of interaction. However, the rotation curve of Wolf–Lundmark–Melotte is asymmetrical, in that the receding side and approaching side of the galaxy are rotating in different ways. Although isolated, Wolf–Lundmark–Melotte shows evidence of ram pressure stripping. It is far outside of the virial radius of the Milky Way, so it is possible that Wolf–Lundmark–Melotte is currently passing through some relatively dense medium. Star formation In 1994, A. E. Dolphin used the Hubble Space Telescope to create a c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Local Group
The Local Group is the galaxy group that includes the Milky Way. It has a total diameter of roughly , and a total mass of the order of . It consists of two collections of galaxies in a "dumbbell" shape: the Milky Way and its satellites form one lobe, and the Andromeda Galaxy and its satellites constitute the other. The two collections are separated by about and are moving toward one another with a velocity of . The group itself is a part of the larger Virgo Supercluster, which may be a part of the Laniakea Supercluster. The exact number of galaxies in the Local Group is unknown as some are occluded by the Milky Way; however, at least 80 members are known, most of which are dwarf galaxies. The two largest members, the Andromeda Galaxy and the Milky Way, are both spiral galaxies with masses of about solar masses each. Each has its own system of satellite galaxies: * The Andromeda Galaxy's satellite system consists of Messier 32 (M32), Messier 110 (M110), NGC 147, NGC 185, A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lensman Series
The ''Lensman'' series is a series of science fiction novels by American author E. E. "Doc" Smith. It was a runner-up for the 1966 Hugo award for Best All-Time Series, losing to the ''Foundation'' series by Isaac Asimov. Plot The series begins with ''Triplanetary'', beginning two billion years before the present time and continuing into the near future. The universe has no life-forms aside from the ancient Arisians, and few planets besides the Arisians' native world. The peaceful Arisians have foregone physical skills in order to develop contemplative mental power. The underlying assumption for this series, based on theories of stellar evolution extant at the time of the books' writing, is that planets form only rarely, and therefore our First and Second Galaxies, with their many billions of planets, are unique. The Eddorians, a dictatorial, power-hungry race, come into our universe from an alien space-time continuum after observing that our galaxy and a sister galaxy (the S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cetus
Cetus () is a constellation, sometimes called 'the whale' in English. The Cetus (mythology), Cetus was a sea monster in Greek mythology which both Perseus and Heracles needed to slay. Cetus is in the region of the sky that contains other water-related constellations: Aquarius (constellation), Aquarius, Pisces (constellation), Pisces and Eridanus (constellation), Eridanus. Features Ecliptic Cetus is not among the 12 true zodiac constellations in the Epoch (astronomy), J2000 epoch, nor classical 12-part zodiac. The ecliptic passes less than 0.25° from one of its corners. Thus the moon and planets will enter Cetus (occulting any stars as a foreground object) in 50% of their successive orbits briefly and the southern part of the sun appears in Cetus for about one day each year. Many asteroids in belts have longer phases occulting the north-western part of Cetus, those with a slightly greater inclination to the ecliptic than the moon and planets. Astronomy on Mars#Celestial pole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virial Radius
In astrophysics, the virial mass is the mass of a gravitationally bound astrophysical system, assuming the virial theorem applies. In the context of galaxy formation and dark matter halos, the virial mass is defined as the mass enclosed within the virial radius r_ of a gravitationally bound system, a radius within which the system obeys the virial theorem. The virial radius is determined using a "top-hat" model. A spherical "top hat" density perturbation destined to become a galaxy begins to expand, but the expansion is halted and reversed due to the mass collapsing under gravity until the sphere reaches equilibrium – it is said to be ''virialized''. Within this radius, the sphere obeys the virial theorem which says that the average kinetic energy is equal to minus one half times the average potential energy, \langle T \rangle = -\frac \langle U \rangle, and this radius defines the virial radius. Virial radius The virial radius of a gravitationally bound astrophysical system i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WLM Galaxy Webb
WLM or wlm may refer to or stand for: Computing * Windows Live Mail, a former e-mail and newsgroup client included in Microsoft's Windows Live group of services * Windows Live Messenger, a former free instant message program by Microsoft * Workload Manager, a resource distributor in IBMs mainframe z/OS operating system Organizations and movements * West London Methodist Mission, a British Methodist mission, also known as West London Mission * White Lives Matter, an international activist group created in response to Black Lives Matter * Women's Liberation Movement, a former political alignment of women and feminist intellectualism Other uses * Middle Welsh, based on its iso language code wlm. * Wiki Loves Monuments Wiki Loves Monuments (WLM) is an annual international photographic competition held during the month of September, organised worldwide by Wikipedia community members with the help of local Wikimedia affiliates across the globe. Participants ..., an annual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Absolute Magnitude
Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse Logarithmic scale, logarithmic Magnitude (astronomy), astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it were viewed from a distance of exactly , without Extinction (astronomy), extinction (or dimming) of its light due to absorption by Interstellar medium, interstellar matter and cosmic dust. By hypothetically placing all objects at a standard reference distance from the observer, their luminosities can be directly compared among each other on a magnitude scale. As with all astronomical magnitude (astronomy), magnitudes, the absolute magnitude can be specified for different wavelength ranges corresponding to specified Filter (optics), filter bands or passbands; for stars a commonly quoted absolute magnitude is the absolute visual magnitude, which uses the visual (V) band of the spectrum (in the UBV phot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Globular Cluster
A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of member stars. Their name is derived from Latin (small sphere). Globular clusters are occasionally known simply as "globulars". Although one globular cluster, Omega Centauri, was observed in antiquity and long thought to be a star, recognition of the clusters' true nature came with the advent of telescopes in the 17th century. In early telescopic observations globular clusters appeared as fuzzy blobs, leading French astronomer Charles Messier to include many of them in his catalog of astronomical objects that he thought could be mistaken for comets. Using larger telescopes, 18th-century astronomers recognized that globular clusters are groups of many individual stars. Early in the 20th century the distribution of globular clusters in the sky w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WLM Globular Cluster
WLM or wlm may refer to or stand for: Computing * Windows Live Mail, a former e-mail and newsgroup client included in Microsoft's Windows Live group of services * Windows Live Messenger, a former free instant message program by Microsoft * Workload Manager, a resource distributor in IBMs mainframe z/OS operating system Organizations and movements * West London Methodist Mission, a British Methodist mission, also known as West London Mission * White Lives Matter, an international activist group created in response to Black Lives Matter * Women's Liberation Movement, a former political alignment of women and feminist intellectualism Other uses * Middle Welsh, based on its iso language code wlm. * Wiki Loves Monuments Wiki Loves Monuments (WLM) is an annual international photographic competition held during the month of September, organised worldwide by Wikipedia community members with the help of local Wikimedia affiliates across the globe. Participants ..., an annual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultraviolet
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun. It is also produced by electric arcs and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights. Although long-wavelength ultraviolet is not considered an ionizing radiation because its photons lack the energy to ionization, ionize atoms, it can cause chemical reactions and causes many substances to glow or fluorescence, fluoresce. Consequently, the chemical and biological effects of UV are greater than simple heating effects, and many practical applications of UV radiation derive from its interactions with organic molecules. Short-wave ultraviolet light damages DNA and sterilizes surf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horizontal Branch
The horizontal branch (HB) is a stage of stellar evolution that immediately follows the red-giant branch in stars whose masses are similar to the Sun's. Horizontal-branch stars are powered by helium fusion in the core (via the triple-alpha process) and by hydrogen fusion (via the CNO cycle) in a shell surrounding the core. The onset of core helium fusion at the tip of the red-giant branch causes substantial changes in stellar structure, resulting in an overall reduction in luminosity, some contraction of the stellar envelope, and the surface reaching higher temperatures. Discovery Horizontal branch stars were discovered with the first deep photographic photometric studies of globular clusters and were notable for being absent from all open clusters that had been studied up to that time. The horizontal branch is so named because in low-metallicity star collections like globular clusters, HB stars lie along a roughly horizontal line in a Hertzsprung–Russell diagram. Because the sta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metallicity
In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal physical matter in the Universe is either hydrogen or helium, and astronomers use the word ''"metals"'' as a convenient short term for ''"all elements except hydrogen and helium"''. This word-use is distinct from the conventional chemical or physical definition of a metal as an electrically conducting solid. Stars and nebulae with relatively high abundances of heavier elements are called "metal-rich" in astrophysical terms, even though many of those elements are nonmetals in chemistry. The presence of heavier elements hails from stellar nucleosynthesis, where the majority of elements heavier than hydrogen and helium in the Universe (''metals'', hereafter) are formed in the cores of stars as they evolve. Over time, stellar winds and supernovae deposit the metals into the surrounding environment, enriching the interstellar medium and providing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
