Beta Persei A/B/C

The position of Algol.
Observation data Epoch J2000
Constellation	Perseus
Right ascension	03h 08m 10.1s
Declination	+40° 57′ 20.3″
Apparent magnitude (V)	1.58
Characteristics
Spectral type	B5-8 V/K02 IV/A5 V
B-V color index	-0.05
U-B color index	-0.37
Variable type	Eclipsing binary
Astrometry
Radial velocity (Rv)	3.7 km/s
Proper motion (μ)	RA: 2.39 mas/yr Dec.: -1.44 mas/yr
Parallax (π)	35.14 ± 0.90 mas
Distance	92.8 ly (28.5 pc)
Absolute magnitude (MV)	-0.69
Details
Mass	3.59/0.79/1.67 M☉
Radius	2.88/3.54/1.7 R☉
Luminosity	98/3.4/4.1 L☉
Temperature	12,500/4,500 K
Metallicity	?
Rotation	65 km/sec.
Age	? years
Other designations
Algol, Gorgona, Gorgonea Prima, Demon Star, El Ghoul, 26 Per, GJ 9110, HR 936, BD +40°673, HD 19356, GCTP 646.00, SAO 38592, FK5 111, Wo 9110, ADS 2362, WDS 03082+4057A, HIP 14576.

Algol (β Per / Beta Persei) is a bright star in the constellation Perseus. It is one of the best known eclipsing binaries, the first such star to be discovered, and also one of the first variable stars in general to be discovered. Algol's magnitude changes regularly between 2.3 and 3.5 over a period of 2 days, 20 hours and 49 minutes. Image File history File links The position of Beta Persei (Algol; Gorgona; Gorgonea Prima; Demon Star; El Ghoul) By Zwergelstern Thanks for the help of Patrick Chevalley File links The following pages link to this file: Algol ... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... Pierce this website is not very reliable!!!!!!!!!!!!!!!!! Some well-known constellations contain striking and familiar patterns of bright stars. ... Perseus with the head of Medusa, by Antonio Canova, completed 1801 (Vatican Museums) Perseus, or Perseos (Greek: Περσεύς, Περσέως), the legendary founder of Mycenae and of the Perseid dynasty there, was the first of the mythic heroes of Greek mythology whose exploits helped establish the hegemony of Zeus and the Twelve Olympians... Right ascension (RA; symbol α: Greek letter alpha; celestial longitude) is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. ... In astronomy, declination (dec) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. ... // Headline text HEY!! HOW ARE YOU ALL?? Its nice of you to come read this page. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequently refined in terms of other characteristics. ... Shanil Davendra Singh rules 4 life! ... Shanil Davendra Singh rules 4 life! ... Most stars are of almost constant luminosity. ... Animation showing how an eclipsing binary stars light intensity changes as they orbit An eclipsing binary star is a binary star in which the orbit plane of the two stars lies so nearly in the line of sight of the observer that the components undergo mutual eclipses. ... This article does not cite its references or sources. ... Radial velocity is the velocity of an object in the direction of the line of sight. ... kilometre per second is an SI derived unit of both speed (scalar) and velocity (vector), signified by the symbol km/s or km s-1. ... The proper motion of a star is the motion of the position of the star in the sky (the change in direction in which we see it, as opposed to the radial velocity) after eliminating the improper motions of the stars, which affect their measured coordinates but are not real... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... Parallax (Greek: παραλλαγή (parallagé) = alteration) is the change of angular position of two stationary points relative to each other as seen by an observer, due to the motion of an observer. ... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... The distance between two points is the length of a straight line segment between them. ... A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ... The parsec (symbol pc) is a unit of length used in astronomy. ... In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standard luminosity distance away from us. ... Mass is a property of a physical object that quantifies the amount of matter it contains. ... In astronomy, the solar mass is a unit of mass used to express the mass of stars and larger objects such as galaxies. ... 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. ... Luminosity has different meanings in several different fields of science. ... The solar luminosity is a unit of luminosity (power emitted in the form of photons) conventionally used by astronomers to give the luminosities of stars. ... Temperature is the physical property of a system which underlies the common notions of hot and cold; the material with the higher temperature is said to be hotter. ... The kelvin (symbol: K) is the SI unit of temperature, and is one of the seven SI base units. ... In astronomy, the metallicity of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium. ... Rotation of a plane, seen as the rotation of the terrain relative to the plane (exposure time 1. ... The Pleiades star cluster A star is a massive body of plasma in outer space that is currently producing or has produced energy through nuclear fusion. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... The Henry Draper Catalogue is an astronomy catalogue with astrometric and spectroscopic data about more than 225,000 stars. ... In astronomy, many stars are referred to simply by catalogue numbers. ... The Smithsonian Astrophysical Observatory (SAO) is a research institute of the Smithsonian Institution headquartered in Cambridge, Massachusetts, where it is joined with the Harvard College Observatory (HCO) to form the Harvard-Smithsonian Center for Astrophysics (CfA). ... In astronomy, many stars are referred to simply by catalogue numbers. ... Beta (upper case Î’, lower case β) is the second letter of the Greek alphabet. ... The Pleiades star cluster A star is a massive body of plasma in outer space that is currently producing or has produced energy through nuclear fusion. ... Pierce this website is not very reliable!!!!!!!!!!!!!!!!! Some well-known constellations contain striking and familiar patterns of bright stars. ... Perseus is a northern constellation, named after the Greek hero who slew the monster Medusa. ... Animation showing how an eclipsing binary stars light intensity changes as they orbit An eclipsing binary star is a binary star in which the orbit plane of the two stars lies so nearly in the line of sight of the observer that the components undergo mutual eclipses. ... Most stars are of almost constant luminosity. ... // Headline text HEY!! HOW ARE YOU ALL?? Its nice of you to come read this page. ...

As an eclipsing binary, it is actually two stars in close orbit around one another. Because the orbital plane coincidentally matches the Earth's line of sight, the dimmer star (Algol B) passes in front of the brighter star (Algol A) once per orbit, and the amount of light reaching Earth is temporarily decreased. To be more precise, however, Algol happens to be a triple star system: the eclipsing binary pair is separated by only 0.062 AU, while the third star (Algol C) is at an average distance of 2.69 AU from the pair and the mutual orbital period is 681 days (1.86 years). The total mass of the system is about 5.8 solar masses, and the mass ratios of A, B and C are about 4.5 : 1 : 2. The orbital plane of an object orbiting another is the geometrical plane in which the orbit is embedded. ... Earth is the third planet from the Sun. ... The astronomical unit (AU or au or a. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ...

The variability of Algol was first recorded in 1670 by Geminiano Montanari, but it is probable that this property was noticed long before this time; the name Algol means "demon star," (from Arabic الغول al-ghūl, "the ghoul") which was probably given due to its peculiar behavior. In the constellation Perseus, it represents the eye of the Gorgon Medusa. 1670 was a common year beginning on a Saturday in countries using the Julian calendar and a Wednesday in countries using the Gregorian calendar. ... Geminiano Montanari. ... The Arabic language (Arabic: ‎ translit: ), or simply Arabic (Arabic: ‎ translit: ), is the largest member of the Semitic branch of the Afro-Asiatic language family (classification: South Central Semitic) and is closely related to Hebrew and Aramaic. ... A ghoul is a monster from ancient Arabian folklore that dwells in graveyards and other uninhabited places. ... Pierce this website is not very reliable!!!!!!!!!!!!!!!!! Some well-known constellations contain striking and familiar patterns of bright stars. ... In Greek mythology, the Gorgons (terrible or, according to some, loud-roaring) were vicious female monsters with sharp fangs and hair of living, venomous snakes. ... A relatively modern image of Medusa painted by Arnold Böcklin In Greek mythology, Medusa (Μεδουσα Queen), was a monstrous female character whose gaze could turn people to stone. ...

Studies of Algol led to the Algol paradox in the theory of stellar evolution: although components of a binary star form at the same time, and massive stars evolve much faster than the less massive ones, it was observed that the more massive component Algol A is still in the main sequence, while the less massive Algol B is a subgiant star at a later evolutionary stage. The paradox can be solved by mass transfer: when the more massive star became a subgiant, it filled its Roche lobe, and most of the mass was transferred to the other star, which is still in the main sequence. In some binaries similar to Algol, a gas flow can actually be seen. In astronomy, stellar evolution is the sequence of changes that a star undergoes during its lifetime, the hundreds of thousands, millions or billions of years during which it emits light and heat. ... Hertzsprung-Russell diagram The main sequence of the Hertzsprung-Russell diagram is the curve where the majority of stars are located in this diagram. ... Subgiant star is a class of stars that are brighter than normal main sequence (dwarf) stars, but not as bright as true giant stars. ... Mass transfer is the phrase commonly used in engineering for physical processes that involve molecular and convective transport of atoms and molecules within physical systems. ... The Roche lobe is the region of space around a star in a binary system within which orbiting material is gravitationally bound to that star. ...

Algol is 92.8 light years from Earth; however, about 7.3 million years ago it passed within 9.8 light years and its apparent magnitude was approximately −2.5, considerably brighter than Sirius is today. Because the total mass of the system is 5.8 solar masses, and despite the fairly large distance at closest approach, this may have been enough to slightly perturb the solar system's Oort cloud and increase the number of comets entering the inner solar system. However, the actual increase in net cratering rate is believed to have been quite small. [1] A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ... // Headline text HEY!! HOW ARE YOU ALL?? Its nice of you to come read this page. ... Sirius (α CMa / α Canis Majoris / Alpha Canis Majoris) is the brightest star in the nighttime sky, with a visual apparent magnitude of −1. ... Presentation of the solar system (not to scale) The solar system comprises the Earths Sun and the retinue of celestial objects gravitationally bound to it. ... This image is an artists rendering of the Oort cloud and the Kuiper Belt. ... Comet Hale-Bopp For other uses, see Comet (disambiguation). ...

Astrologically, Algol is considered the most unfortunate star in the sky. In the Middle Ages it was one of the 15 Behenian stars, associated with the diamond and hellebore, and marked with the kabbalistic sign . Astrology refers to any of several systems, traditions or beliefs in which knowledge of the apparent positions of celestial bodies is held to be useful in understanding, interpreting, and organizing knowledge about human affairs and events on earth. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... The Middle Ages formed the middle period in a traditional schematic division of European history into three ages: the classical civilization of Antiquity, the Middle Ages, and modern times, beginning with the Renaissance. ... List of Behenian Stars Caput Algol (Algols head, associated with the head of Gorgona), Pleiades (actually, several stars), Aldebaran, Alhayhoch, Canis Maior (actually, a constellation, like the next one), Canis Minor, Cor Leonis (Hearth of the Lion), Cauda Urse (Tail of the Bear), Ala Corvi (Wing of the crow... For other uses, see Diamond (disambiguation). ... Species See text(#Species) Hellebores (the Genus Helleborus in the Family Ranunculaceae) are perennial flowering plants that are often grown in gardens for decorative purposes, as well as for their purported medicinal abilities and uses in witchcraft. ... The tree of life Kabbalah (קבלה Reception, Standard Hebrew Qabbala, Tiberian Hebrew Qabbālāh; also written variously as Cabala, Cabalah, Cabbala, Cabbalah, Kabala, Kabalah, Kabbala, Qabala, Qabalah) is a religious philosophical system claiming an insight into divine nature. ... Image File history File links after Agrippa File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...

External links

• Discusses the history of Algol
• SolStation article
• ARICNS entry
• MainStars data
• Algol by Jim Kaler