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Topic: Variable star designation

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Leo constellation

Draco (constellation)

Cancer (constellation)

	Variable star Summary
		Variable stars of this type only occur when the binary star system is properly aligned for the observer to see one member being eclipsed by the other.
		Variability of T Tauri stars is due to spots on the stellar surface and gas-dust clumps, orbiting in the circumstellar disks.
		Stars with sizable sunspots may show significant variations in brightness as they rotate, and brighter areas of the surface are brought into view.
	www.bookrags.com /Variable_star (4064 words)

	Variable star - Wikipedia, the free encyclopedia
		Variable stars are generally analysed using photometry and photospectrometry.
		For regular variables, the period of variation and its amplitude can be very well established; for many variable stars, though, these quantities may vary slowly over time, or even from one period to the next.
		Stars with sizable sunspots may show significant variations in brightness as they rotate, and brighter areas of the surface are brought into view.
	en.wikipedia.org /wiki/Variable_star (1250 words)

	Star - Encyclopedia.WorldSearch (Site not responding. Last check: 2007-11-03)
		Scientifically, stars are defined as self-gravitating spheres of plasma in hydrostatic equilibrium, which generate their own energy through the process of nuclear fusion.
		Stellar astronomy is the study of stars and the phenomena exhibited by the various forms/developmental stages of stars.
		As learned by star formation astronomers, stars are born in molecular clouds, large regions of slightly higher density of matter (though still less dense than the inside of an earthly vacuum chamber), and form by gravitational instability inside those clouds triggered by shockwaves from supernovae.
	encyclopedia.worldsearch.com /star.htm (1448 words)

	Variable star designation - Wikipedia, the free encyclopedia
		Variable stars are named using a variation on the Bayer designation format of an identifying label (as described below) combined with the Latin genitive of the name of the constellation in which the star lies.
		In previous centuries few variable stars were known, so it seemed reasonable to use the letters of the Roman alphabet, starting from the letter R so as to avoid confusion with letter spectral types or the (now rarely used) Latin-letter Bayer designations.
		This system of nomenclature was developed by Friedrich W. Argelander, who noted that many variable stars were red and so began the naming with the letter R for rot ("red" in German).
	en.wikipedia.org /wiki/Variable_star_designation (295 words)

	Variable star -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-11-03)
		Variable stars are generally analysed using (Measurement of the proterties of light (especially luminous intensity)) photometry and photospectrometry.
		For regular variables, the (A unit of geological time during which a system of rocks formed) period of variation and its (Greatness of magnitude) amplitude can be very well established; for many variable stars, though, these quantities may vary slowly over time, or even from one period to the next.
		Stars with sizable (A cooler darker spot appearing periodically on the sun's photosphere; associated with a strong magnetic field) sunspots may show significant variations in brightness as they rotate, and brighter areas of the surface are brought into view.
	www.absoluteastronomy.com /encyclopedia/v/va/variable_star.htm (1614 words)

	Learn more about Star designation in the online encyclopedia. (Site not responding. Last check: 2007-11-03)
		Note that there are companies that purport to name obscure stars after paying customers, but these names are recognized by nobody except the registering company and the customer, and there is nothing to stop two companies from claiming the same star, or even one company from registering the same star to two customers.
		Johann Bayer introduced a system of designating the brightest stars in each constellation by means of Greek (or less often) Latin letters, a system which is still widely used.
		Variable stars which do not have Bayer designations are given special designations which mark them out as variable stars.
	www.onlineencyclopedia.org /s/st/star_designation.html (373 words)

	Bayer designation - Wikipedia
		These designations, which were introduced by Johann Bayer in his star atlas Uranometria in 1603, consist of a Greek letter followed by the genitive of the name of the constellation in which the star lies.
		In practice, there are numerous examples where the designations are out of order, and there are even cases where a star has a designation for a constellation in which it does not lie (according to the modern constellation boundaries).
		Note that uppercase Latin Bayer designations never went beyond Q, and names such as W Virginis are variable designations, not Bayer designations.
	nostalgia.wikipedia.org /wiki/Bayer_designation (347 words)

	GCVSEGVARS - General Catalog of Variable Stars (GCVS4.2): Extragalactic Variables
		An alternative designation for the variable star that is used in the reference whose code is given in the ref_star parameter.
		An alternative designation for the variable star that is used in the reference whose code is given in the ref_chart parameter.
		This is a flag indicating the nonmembership status of the variable star in the Galaxy in whose field the star lies.
	starchild.gsfc.nasa.gov /W3Browse/star-catalog/gcvsegvars.html (1499 words)

	How to Read the Grazing Occultation Limit Predictions
		TANZ The tangent of the zenith angle of the star.
		During lunar eclipses, the cusp angle is meaningless and is replaced by the UMBRAL DISTANCE, the distance of the star from the center of the umbra, expressed as a percent of the radius of the umbra.
		LINE 2 The star number in the ZC or X catalog, the version of the USNO profile prediction program that generated the data for the plot, and the longitude libration of the graze are given.
	www.lunar-occultations.com /iota/grlimit.htm (5019 words)

	NASA - Star
		A star with an absolute magnitude of -3 is 100 times as luminous as a star whose absolute magnitude is 2 and 10,000 times as luminous as a star that has an absolute magnitude of 7.
		Dark red stars have surface temperatures of about 2500 K. The surface temperature of a bright red star is approximately 3500 K; that of the sun and other yellow stars, roughly 5500 K. Blue stars range from about 10,000 to 50,000 K in surface temperature.
		The hottest stars in a spectral class are assigned the numeral 0; the coolest stars, the numeral 9.
	www.nasa.gov /worldbook/star_worldbook.html (6934 words)

	AAVSO: RU Vir
		Because the Mira stars are in the stage of their evolution during which most of their mass is returned to the galaxy through stellar winds and mass loss, they are a key mechanism for cosmic chemical enrichment for new generations of stars.
		By the end of the 20th Century, the long-term light variations of RU Vir proved to be cyclical, and the natures of this star and similar stars were under intense scrutiny by the astronomical community.
		Since the AGB stars soon begin to return some of their mass to interstellar space, the study of carbon stars and other AGB stars is crucially important in understanding the chemical enrichment of the interstellar medium.
	www.aavso.org /vstar/vsots (2782 words)

	[No title]
		The designation is either a letter from R to Z, or two letters, or V plus a number, and a constellation.
		X-ray jet variable An X-ray jet variable is an X-ray variable star where the matter falling on the neutron star or white dwarf or fl hole gives rise to jets.
		In the case of X-ray jet stars, the jets are moving at a significant fraction of the speed of light.
	www.projectpluto.com /gloss/help_19.htm (3214 words)

	AAVSO: AAVSO Section
		The brightness changes of these stars can range from a thousandth of a magnitude to as much as twenty magnitudes over periods of a fraction of a second to years, depending on the type of variable star.
		Variable stars need to be systematically observed over decades in order to: determine the long-time behavior of a star, provide professional astronomers with data needed to analyze variable star behavior, to schedule observations of certain stars, to correlate data from satellite and ground-based observations, and to make computerized theoretical models of variable stars.
		Cepheid Variables have played a pivotal role in determining distances to far away galaxies and the age of the universe.
	www.aavso.org /vstar (377 words)

	Astronomical Association of Queensland
		The star received the preliminary designation BV520 and was subsequently included in the New Catalogue of Suspected Variable Stars (NSV) with the designation NSV6708.
		The RCB variable stars are evolved F and G supergiants whose atmosphere is rich in carbon and deficient in hydrogen, but with other elements at near solar abundances.
		Variable star charts 932 and 933 from the RASNZ VSS for V854 Centauri are shown opposite.
	www.aaq.org.au /variablestars_V854Centauri.htm (1350 words)

	Variable star designation -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-11-03)
		Variable stars are named using a variation on the (Click link for more info and facts about Bayer designation) Bayer designation format of Identifier
		In previous centuries few variable stars were known, so it seemed reasonable to use the letters of the (The alphabet evolved by the ancient Romans which serves for writing most of the languages of western Europe) Roman alphabet, starting from the letter R so as to avoid confusion with letter spectral types.
		Sample designations are (Click link for more info and facts about R Coronae Borealis) R Coronae Borealis, YY Geminorum, and V348 Sagitarii.
	www.absoluteastronomy.com /encyclopedia/V/Va/Variable_star_designation.htm (208 words)

	Wolf 1055 AB / Van Biesbroeck's Star
		Both Stars A and B are flare stars, but the fainter member of the system was once thought to be low enough in mass to be a possible brown dwarf and is now commonly referred to as "Van Biesbroeck's Star" (or VB 10) after its discovery in 1940 by George Van Biesbroeck (1880-1974).
		Although the star's normal surface temperature is 4,500° F, the sudden burst heated VB 10's outer atmosphere to around 270,000° F. The astronomers attributed this rapid heating to the presence of an intense, but unstable, magnetic field (Linsky et al, 1995).
		Hence, Earth-type life around flare stars may be unlikely because their planets must be located very close to dim red dwarfs to be warmed sufficiently by star light to have liquid water (less than 0.08 AU for Wolf 1055 A or B), which makes flares even more dangerous around such stars.
	www.solstation.com /stars/wolf1055.htm (1236 words)

	The names and catalogues of variable stars
		The variable stars known in those days were scarce and it was sufficient to refer to "the variable in the Lion" or the one in Andromeda for every astronomer to know what star was talked of.
		I hope I will be forgiven for taking the liberty of designating by a letter a star which does not appear in the Bayer catalogue but it seems to me that owing to their originality, variable stars are entitled to claim such a distinction.
		As variable stars were being discovered at an accelerating pace, the Harvard Observatory had proposed to designate them with a 6-digit number, the first four representing the Right Ascension of the star expressed in hours and minutes, the last two representing the declination in degrees for the equinox 1900.
	cdsweb.u-strasbg.fr /afoev/var/edenom.htx (2706 words)

	General Catalogue of Variable Stars: Vols I-III (the new electronic version). (Site not responding. Last check: 2007-11-03)
		67-77 contain variable stars designated between 1982 and 2003; these stars are also incorporated in the combined catalog, but note that their cross-identifications with astronomical catalogues as well as remarks and references may be found in the file nl.zip, which is a complete electronic version of the Name-lists.
		All variables in the present data set are arranged in the order of their names inside constellations.
		Second, it is used for all variables of the Name-Lists Nos.67-76, it is followed by the two-digit number of the Name-list and the four-digit number of the star in the Name-list, and the information for the star follows the format of the Name-lists (see above).
	www.sai.msu.su /groups/cluster/gcvs/gcvs/iii (1504 words)

	Variable Star Naming (Site not responding. Last check: 2007-11-03)
		Variable stars are those stars that change their apparent brightness (or sometimes their color) over time.
		The second variable star discovered in that constellation is called S, the third T, then U, then V, then W, then X, then Y, and then Z. This covers the first nine variable stars discovered in any given constellation.
		The tenth variable star to be discovered in a constellation is named RR.
	www.stellar-database.com /variable.html (317 words)

	Semiregular variable star (Site not responding. Last check: 2007-11-03)
		Semiregular variable stars are giants or supergiants of intermediate and late spectral type showing considerable periodicity in their light changes, accompanied or sometimes interrupted by various irregularities.
		Amplitudes and light-curve shapes generally vary and periods are in the range of 35-1200 days.
		Amplitudes of light variation are in the range from 0.1 to 4 mag, and the range of periods is from 30 to 1100 days.
	www.sciencedaily.com /encyclopedia/semiregular_variable_star (383 words)

	Wolf 359
		The fifth nearest star (third nearest star system) to the Sun, after the Alpha Centauri trinary and Barnard’s Star; it lies in the constellation Leo.
		Discovered by Max Wolf in 1918, Wolf 359 is an extremely faint red dwarf that for 25 years was the least luminous star known.
		It is also a flare star with the variable star designation CN Leonis, and in 2001 became the first star, other than the Sun, to have its corona registered by near-optical ground-based detection when an emission line of highly ionized iron (Fe XIII at 3,388 Å) was reported.
	www.daviddarling.info /encyclopedia/W/Wolf_359.html (173 words)

	Cygnus X 1 (Site not responding. Last check: 2007-11-03)
		It is a high-mass X-ray binary, with the optical counterpart (HDE 226868) being a variable star 8.9 Apparent magnitude star (visible with good binoculars in good observing conditions.) at right ascension 19 h 56.5 min and declination of 35 deg 4 min (for 1950 epoch (astronomy)).
		Cyg X-1 is a binary star that contains a Stellar classification supergiant (with a surface temperature of 31000 kelvins) and a compact object.
		The compact object has a mass of 7-13 solar masses, as the largest possible mass of a neutron star can not exceed three solar masses, it is believed to be a fl hole.
	read-and-go.hopto.org /Variable-stars/Cygnus-X-1.html (225 words)

	The Universe within 12.5 Light Years - The Nearest stars
		Roughly eighty percent of all the stars in the universe are red dwarfs, and the nearest star - Proxima - is a typical example.
		Recorded in JJ Lalande's star catalogue compiled in the 1790's, this is one of the brightest red dwarfs in the sky, but still requires binoculars to see it.
		Both stars are variable in brightness and have the variable star names of GX And and GQ And.
	www.ldps.ws /Mirror/Universe/12lys.html (1054 words)

	Nearby Stars
		The stars were discovered in 1949 by Willem Jacob Luyten (1899-1994), who found the proper motions of over 520,000 stars despite the loss of sight in one eye since 1925 by building an automated photographic plate scanner and measuring machine.
		There also may be an optical companion star seen in telescopes that is not actually bound by gravity to Tau Ceti, and the star does not appear to have a dim stellar or substellar companion based on astrometric measurements (Lippincott and Worth, 1980) or radial velocity variations (Campbell et al, 1988).
		It is the first star to be found to have a disk of dust and comets around it similar in size and shape to the disk of comets and asteroids that orbits the Sun.
	hyperphysics.phy-astr.gsu.edu /hbase/starlog/grm34.html (1541 words)

	constellation (Site not responding. Last check: 2007-11-03)
		In three-dimensional space, most of the stars we see have little relation to one another, but can appear to be grouped on the celestial sphere of the night sky.
		The stars in a constellation or asterism rarely have any astrophysical relationship to each other; they just happen to appear close together in the sky as viewed from Earth and typically lie many light years apart in space.
		The grouping of stars into constellations is essentially arbitrary, and different cultures have had different constellations, although a few of the more obvious ones tend to recur frequently, e.g., Orion and Scorpio.
	copernicus.subdomain.de /constellation (479 words)

	early star concept from the Astronomy knowledge base (Site not responding. Last check: 2007-11-03)
		A star (25 kinds, 226 facts) - Star with spectral type A in which the spectrum of the Balmer lines of hydrogen attain their greatest strength.
		B star (30 kinds, 239 facts) - Blue-white star of spectral type B whose spectra are characterized by absorption lines of neutral helium which reach their maximum intensity at B2.
		F star (12 kinds, 135 facts) - Star of spectral type F in which lines of hydrogen and Ca II are of about equal strength.
	www.csi.uottawa.ca:4321 /astronomy/earlystar.html (777 words)

	Nearby Stars Ross 128, Ross 154, and Ross 248
		Ross 128 would be only one of many unremarkable stars except that it appears to be a flare star as well as one of Sol's closest neighbors.
		Ross 154 is a dim, main-sequence red dwarf that is comparable to the two stars, Gliese 623a and the dimmer Gliese 623b, shown in the NASA HST image at left.
		Ross 154 would be only one of many unremarkable stars except that it appears to be a flare star as well as one of Sol's closest neighbors.
	hyperphysics.phy-astr.gsu.edu /Hbase/Starlog/ross.html (656 words)

	variable concept from the Astronomy knowledge base (Site not responding. Last check: 2007-11-03)
		Some variables vary simply because they consist of two stars, one of which eclipses the other; Algol is the most famous example.
		Other variables, however, vary because the stars themselves actually change in brightness; the most famous are the Cepheids, RR Lyraes, and Miras, all of which pulsate.
		Be star (1 kind, 9 facts) - Irregular variables of spectral type B (or occasionally O or A) with hydrogen emission lines in their spectra.
	www.site.uottawa.ca:4321 /astronomy/variable.html (589 words)

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