The position of Algol

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 ... 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 ... Beta (upper case Î’, lower case β) is the second letter of the Greek alphabet. ... The Pleiades star cluster A star is any massive gaseous body in outer space. ... Orion is a remarkable constellation, visible from most places on the globe (but not always the whole year long). ... Perseus is a northern constellation, named after the Greek hero who slew the monster Medusa. ... 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 nearly constant luminosity. ... The apparent magnitude (m) of a star, planet or other heavenly body is a measure of its apparent brightness; that is, the amount of light received from the object. ...

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 is an astronomical concept. ... Earth, also known as the Earth, Terra, and (mostly in the 19th century) Tellus, is the third planet outward 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. ... Arabic (العربية al-arabiyyah, or less formally arabi) 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. ... Ghouls are a variety of monster that come from Arab folklore. ... Orion is a remarkable constellation, visible from most places on the globe (but not always the whole year long). ... 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 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 which 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. 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. ... Presentation of the Solar system (not to scale). ... This image is an artists rendering of the Oort cloud and the Kuiper Belt. ... Comet Hale-Bopp, showing a white dust tail and blue gas tail (February 1997) A comet is a small body in the solar system that orbits the sun and (at least occasionally) exhibits a coma (or atmosphere) and/or a tail -- both due primarily to the effects of solar radiation...

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 . An astrological chart (or horoscope) - Y2K Chart — This particular chart is calculated for January 1, 2000 at 12:01:00 A.M. Eastern Standard Time in New York City, New York, USA. (Longitude: 074W0023 - Latitude: 40N4251), using the tropical zodiac Astrology (from Greek: αστρολογία = άστρον, astron, star + λόγος, logos, word) is... This article is about good and bad fortune. ... 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... A scattering of round-brilliant cut diamonds shows off the many reflecting facets. ... Hellebore (Ranunculaceae helleborus) is a white flower often grown in gardens for decorative purposes, as well as for 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
• http://www.solstation.com/stars2/algol3.htm