Flare starA flare star is a variable star that can undergo unpredictable dramatic increases in brightness for a few minutes. It is believed that the flares on flare stars are analogous to solar flares in that they are due to the magnetic energy stored in the stars' atmospheres. The brightness increase is across the spectrum, from X-rays to radio waves. Flare activity among late-type stars was first reported by A. van Maanen in 1945, for WX UMa and YZ CMi. However, the best-known flare star is UV Ceti, first observed to flare in 1948.
Variable (computer science)In computer programming, a variable is an abstract storage location paired with an associated symbolic name, which contains some known or unknown quantity of data or object referred to as a value; or in simpler terms, a variable is a named container for a particular set of bits or type of data (like integer, float, string etc...). A variable can eventually be associated with or identified by a memory address. The variable name is the usual way to reference the stored value, in addition to referring to the variable itself, depending on the context.
Stellar designations and namesIn astronomy, stars have a variety of different stellar designations and names, including catalogue designations, current and historical proper names, and foreign language names. Only a tiny minority of known stars have proper names; all others have only designations from various catalogues or lists, or no identifier at all. Hipparchus in the 2nd century BC enumerated about 850 naked-eye stars. Johann Bayer in 1603 listed about twice this number. Only in the 19th century did star catalogues list the naked-eye stars exhaustively.
Giant starA giant star is a star with substantially larger radius and luminosity than a main-sequence (or dwarf) star of the same surface temperature. They lie above the main sequence (luminosity class V in the Yerkes spectral classification) on the Hertzsprung–Russell diagram and correspond to luminosity classes II and III. The terms giant and dwarf were coined for stars of quite different luminosity despite similar temperature or spectral type by Ejnar Hertzsprung about 1905.
Irregular galaxyAn irregular galaxy is a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy. Irregular galaxies do not fall into any of the regular classes of the Hubble sequence, and they are often chaotic in appearance, with neither a nuclear bulge nor any trace of spiral arm structure. Collectively they are thought to make up about a quarter of all galaxies. Some irregular galaxies were once spiral or elliptical galaxies but were deformed by an uneven external gravitational force.
AntaresAntares is the brightest star in the constellation of Scorpius. It has the Bayer designation α Scorpii, which is Latinised to Alpha Scorpii. Often referred to as "the heart of the scorpion", Antares is flanked by σ Scorpii and τ Scorpii near the center of the constellation. Distinctly reddish when viewed with the naked eye, Antares is a slow irregular variable star that ranges in brightness from an apparent visual magnitude of +0.6 down to +1.6. It is on average the fifteenth-brightest star in the night sky.
Interacting galaxyInteracting galaxies (colliding galaxies) are galaxies whose gravitational fields result in a disturbance of one another. An example of a minor interaction is a satellite galaxy disturbing the primary galaxy's spiral arms. An example of a major interaction is a galactic collision, which may lead to a galaxy merger. A giant galaxy interacting with its satellites is common. A satellite's gravity could attract one of the primary's spiral arms.
Wilkinson Microwave Anisotropy ProbeThe Wilkinson Microwave Anisotropy Probe (WMAP), originally known as the Microwave Anisotropy Probe (MAP and Explorer 80), was a NASA spacecraft operating from 2001 to 2010 which measured temperature differences across the sky in the cosmic microwave background (CMB) – the radiant heat remaining from the Big Bang. Headed by Professor Charles L. Bennett of Johns Hopkins University, the mission was developed in a joint partnership between the NASA Goddard Space Flight Center and Princeton University.
SupergiantSupergiants are among the most massive and most luminous stars. Supergiant stars occupy the top region of the Hertzsprung–Russell diagram with absolute visual magnitudes between about −3 and −8. The temperature range of supergiant stars spans from about 3,400 K to over 20,000 K. The title supergiant, as applied to a star, does not have a single concrete definition. The term giant star was first coined by Hertzsprung when it became apparent that the majority of stars fell into two distinct regions of the Hertzsprung–Russell diagram.
Variable-star designationIn astronomy, a variable-star designation is a unique identifier given to variable stars. It uses a variation on the Bayer designation format, with an identifying label (as described below) preceding the Latin genitive of the name of the constellation in which the star lies. See List of constellations for a list of constellations and the genitive forms of their names. The identifying label can be one or two Latin letters or a V plus a number (e.g. V399). Examples are R Coronae Borealis, YZ Ceti, V603 Aquilae.
