NationMaster - Encyclopedia: Supergiant

Supergiants are the most massive stars. In the Hertzsprung-Russel diagram they occupy the top region of the diagram. In the Yerkes spectral classification supergiants are class Ia (most luminous supergiants) or Ib (less luminous supergiants). The most luminous supergiants are often classified as hypergiants of class 0. STAR is an acronym for: Scientific and Technological Advanced Research Labs, a fictional research organization in the DC Comics universe. ... Hertzsprung-Russell diagram In stellar astronomy, the Hertzsprung-Russell diagram (usually referred to by the abbreviation H-R diagram) shows the mathematical relationship between absolute magnitude, luminosity, stellar classification, and surface temperature. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequenly refined in terms of other characteristics. ... A hypergiant is a massive star, larger than even a supergiant, with a mass up to 100 times that of our Sun. ...

Supergiants can have masses from 10 to 70 solar masses and brightness from 30,000 up to hundreds of thousands times the solar luminosity. They vary greatly in radii, usually from 30 to 500, or even in excess of 1000 solar radii. The Stefan-Boltzmann law dictates that the relatively cool surfaces of red supergiants radiate much less energy per unit area than those of blue supergiants; thus, for a given luminosity red supergiants are larger than their blue counterparts. For other uses, see Sun (disambiguation). ... Luminosity has different meanings in several different fields of science. ... In classical geometry, a radius of a circle or sphere is any line segment with one endpoint on the circle (i. ... In astronomy, the solar radius is a unit of length used to express the size of stars and larger objects such as galaxies. ... Stefan-Boltzmann law (also Stefans law) states that tom is a brain the total energy radiated per unit surface area of a black body in unit time (black-body irradiance), (or the energy flux density (radiant flux) or the emissive power), j* is directly proportional to the fourth power...

Because of their extreme masses they have short lifespans of only 10 to 50 million years and are only observed in young cosmic structures such as open clusters, the arms of spiral galaxies, and in irregular galaxies. They are less abundant in spiral galaxy bulges, and are not observed in elliptical galaxies, or globular clusters, all of which are believed to be composed of old stars. An open cluster is a group of up to a few thousand stars that were formed from the same giant molecular cloud, and are still loosely gravitationally bound to each other. ... A spiral galaxy is a type of galaxy in the Hubble sequence which is characterized by the following physical properties: Spiral Galaxy M74 presents a face-on view of its spiral arms. ... An irregular galaxy is a galaxy that does not fall into the Hubble classification for galaxies. ... An elliptical galaxy is a type of galaxy in the Hubble sequence characterized by the following physical properties: The giant elliptical galaxy NGC 4881 (the spherical glow at upper left) lies at the edge of the Coma Cluster of Galaxies. ... A globular cluster is a spherical bundle of stars (star cluster) that orbits a galaxy as a satellite. ...

Supergiants occur in every spectral class from young blue class O supergiants stars to highly evolved red class M supergiants. Rigel, the brightest star in the constellation Orion is a typical blue-white supergiant, whereas Betelgeuse and Antares are red supergiants. In the fictional Star Trek universe, a Class M planet is the classification used to refer to planet that is suitable for supporting life. ... Rigel (pronounced ) (Î² Orionis) is the brightest star in the constellation Orion and the seventh brightest star in the sky, with visual magnitude 0. ... Orion is a remarkable constellation, visible from most places on the globe at one time or another during the year. ... Orion, a constellation often referred to as The Hunter, is a prominent constellation, perhaps the best-known in the sky. ... Hubble UV picture of Betelgeuse. ... This article is about the star. ... Red supergiants are supergiant stars of spectral type M. See also Blue supergiant Categories: Star stubs | Star types | Red supergiants ...

The modelling of supergiants is still an active area of research and is made more difficult by issues such as stellar mass loss. Rather than modelling individual stars, the latest trend has been to model clusters of stars and then compare the distribution of the resulting models with the observed supergiant distributions in galaxies like the Magellanic Clouds. The two Magellanic Clouds are irregular dwarf galaxies orbiting our Milky Way galaxy, and thus are members of our Local Group of galaxies. ...

The first stars in the universe are thought to have been considerably brighter and more massive than the stars in modern universe. These stars were part of the theorized population III of stars. Their existence is necessary to explain observations of elements other than hydrogen and helium in quasars. The deepest visible-light image of the cosmos. ... Population III stars are a hypothetical population of extremely massive stars that are believed to have been formed in the early universe. ... A chemical element, often called simply element, is a chemical substance that cannot be divided or changed into other chemical substances by any ordinary chemical technique. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ... This view, taken with infrared light, is a false-color image of a quasar-starburst tandem with the most luminous starburst ever seen in such a combination. ...

Most type II supernova progenitors are thought to be red supergiants. However, the progenitor for Supernova 1987A was a blue supergiant. It is believed that it was a red supergiant before losing its outer layers to the strong stellar wind. Multiwavelength X-ray image of the remnant of Keplers Supernova, SN 1604. ... 1987A supernova remnant near the center SN 1987A was a supernova in the Large Magellanic Cloud, a nearby dwarf galaxy. ... Blue supergiants are supergiant stars of spectral type O. They are extremely hot and bright, with surface temperatures of between 20,000 - 50,000Â°C. They typically have 10 to 50 solar masses on the Hertzsprung-Russell diagram, and can have radii up to about 25 solar radii. ... A solar wind is a stream of particles (mostly high-energy protons ~ 500 keV) which are ejected from the upper atmosphere of a star (in the case of a star other than the Earths Sun, it may be called a stellar wind instead). ...

Currently, the largest known stars in terms of physical size, not mass or luminosity, are the supergiants KW Sagitarii, KY Cygni, V354 Cephei, VV Cephei, and μ Cephei (the Garnet Star). KY Cygni is a red supergiant star located in the constellation Cygnus. ... VV Cephei is a star located in the constellation Cepheus. ... Mu Cephei (Î¼ Cep / Î¼ Cephei) is a star in the constellation Cepheus. ...