Stars ADS O.J. Algol (Beta Persei), known informally as the Demon Star, is a triple star system in which the components are designated Beta Persei Aa1, Aa2, and Ab, respectively. The three components of the bright triple star used to be, and still sometimes are, referred to as β Per A, B, and C. The Washington Double Star Catalog lists them as Aa1, Aa2, and Ab, with two very faint stars B and C about one arcmin distant. The x-ray flares are thought to be caused by the magnetic fields of the A and B components interacting with the mass transfer. [21] This was confirmed a few years later, in 1889, when the Potsdam astronomer Hermann Carl Vogel found periodic doppler shifts in the spectrum of Algol, inferring variations in the radial velocity of this binary system. This type of variable star is called an eclipsing binary system, and Algol was the first system of this kind to be discovered. This means they can be predicted so that we know when to watch for them. The Algol system is located within the constellation Perseus, which is visible from latitudes of between +90° and -35°, although best seen at about 9 PM (Local Time) during the month of December, when it is highest in the sky. The Algol system is also strong emitter of X-rays and radio wave flares, although the exact origins and/or causes of the emissions are not known for certain. In some binaries similar to Algol, a gas flow can be seen. The name Algol derives from Arabic رأس الغول raʾs al-ghūl : head (raʾs) of the ogre (al-ghūl) (see "ghoul"). [18][19] In May 1783, he presented his findings to the Royal Society, suggesting that the periodic variability was caused by a dark body passing in front of the star (or else that the star itself has a darker region that is periodically turned toward the Earth). In the Tetrabiblos, the 2nd-century astrological text of the Alexandrian astronomer Ptolemy, Algol is referred to as "the Gorgon of Perseus" and associated with death by decapitation: a theme which mirrors the myth of the hero Perseus's victory over the snake-haired Gorgon Medusa. Algol is a multiple-star system with three confirmed and two suspected stellar components. As can be seen from the image above, Capella in Auriga and the Pleiades in Taurus form a huge celestial triangle with Mirfak, the brightest star in Perseus, with Algol easily located just a few degrees to its right. However, the actual increase in cometary collisions in the inner solar system following the Algol system’s passing is generally believed to be relatively low as compared to other periods in the region’s history. In the case of the X-ray emissions, most investigators believe that these are caused by the magnetic fields of the primary stars interacting with the mass being transferred between them, while the radio flares are thought by some investigators to be caused by magnetic cycles on these stars that are somewhat similar to sunspots on the Sun. The eclipsing binary pair is separated by only 0.062 astronomical units (au) from each other, whereas the third star in the system (Algol Ab) is at an average distance of 2.69 au from the pair, and the mutual orbital period of the trio is 681 Earth days. Algol’s variability was first correctly explained by the English amateur astronomer John Goodricke in 1782, when he was only 18 years of age. A series of observations on, and a discovery of, the period of the variation of the light of the bright star in the head of medusa, called algol. At this time, the system would have had an apparent visual magnitude of about -2.5, which is several times brighter than the star Sirius is today. The light curve revealed the second minimum and the reflection effect between the two stars. In a letter from John Goodricke, Esq. • Luminosity: (Aa1) 182 sol 1", AEEA (Activities of Exhibition and Education in Astronomy), https://en.wikipedia.org/w/index.php?title=Algol&oldid=988755023, Astronomical objects known since antiquity, Articles with Chinese-language sources (zh), Short description is different from Wikidata, Articles containing Chinese-language text, Articles which use infobox templates with no data rows, Wikipedia articles needing clarification from July 2011, Creative Commons Attribution-ShareAlike License, This page was last edited on 15 November 2020, at 01:50. [15] The Arabic astronomer al-Sufi said nothing about any variability of the star in his Book of Fixed Stars published c.964. As the more massive star expands during the normal course of its evolution, it sometimes fills and exceeds its Roche lobe, and thus some of its mass is transferred onto the less massive star. The most interesting aspect of the Algol system involves the Algol Paradox, which had confounded investigators for a long time. • Surface Temperature: (Aa1) 13,000K It shows the dimmer companion star orbiting Algol and passing in front of it — a classic eclipsing binary star system. • Coordinates: RA 3h 8m 10s|Dec +40° 57′ 20″ Most people who identify as Starseeds also share the belief that they have not only lived on other planets before, but that their genes also possess extraterrestrially encoded DNA that influence their psyches in specific ways – this will be explored below Note, however, that a further seven faint stars are listed in the Washington Double Star Catalog as being members of the Algol system. Algol is a three-star system consisting of Beta Persei Aa1, Aa2, and Ab. The Starseed generally possesses a strong life-purpose and a deep underlying feeling of having a mission to fulfill on Earth. It is located at around 90 light-years / 28 parsecs away from the Sun. The first star, which was recognized as being an eclipsing binary, is a fairly bright star in the constellation of perseus ... A binary star system in which both stars are seen as slowly orbiting separate points of light. (We now know there is a third star in the Algol system, but it is not involved in the eclipses.) [37] Mass transfer between the components is small in the Algol system[38] but could be a significant source of period change in other Algol-type binaries. G. Montanari, "Sopra la sparizione d'alcune stelle et altre novità celesti", in: Meltzer, Alan S., A "Spectroscopic Investigation of Algol". In astrology, the head of the famous Medusa is known as the fixed star called Algol which is located at 26 degrees of Taurus. The stars’ orbit around each other takes 9.6 days, so the eclipses occur at highly regular intervals. For example, the Jan 3, 21h, eclipse will yield consecutive eclipse times on Jan 6, 18h, then Jan 9, 15h, then Jan 12, 12h, etc. An Ancient Egyptian Calendar of Lucky and Unlucky Days composed some 3,200 years ago is claimed to be the oldest historical documentation of the discovery of Algol. [11][12] (adsbygoogle = window.adsbygoogle || []).push({}). At issue is the fact that while the more massive star (Algol Aa1) in the system is still on the main sequence, the less massive secondary component (Algol Ab) is a sub-giant star that is at a much later evolutionary stage. In China, Algol is known by another grim name- “The Fifth Star of Mausoleum”, on account of its position in an asterism known as “Mausoleum”, which is made up of a number of other stars in the Perseus constellation. Algol is a known variable star, which waxes and wanes in brightness. [42] Hipparchus and Pliny made this a separate, though connected, constellation. Algol, Gorgona, Gorgonea Prima, Demon Star, El Ghoul, β Persei, β Per, 26 Persei, The constellation Perseus and Algol, the Bright Star in the Gorgon's head. Just knowing what kind of eclipsing binary system is present can be difficult enough, without the added challenge of distinguishing planets. It is so entered on the IAU Catalog of Star Names. [22] Thus Algol became one of the first known spectroscopic binaries. Here are a few examples of eclipsing binary systems: EA (Algol Type) Algol (Beta Persei) type eclipsing systems have spherical or slightly ellipsoidal components. • Radius: (Aa1) 2.73 sol [41] The English name Demon Star was taken from the Arabic name. Algol, Beta Persei (β Per) is a triple star system located in the constellation Perseus. • Rotational Velocity: 49 km/sec • Star Type: Aa1: B8V /Aa2: K0IV /Ab: A7m The third star in the system (Ab) is a magnitude 2.3 A-type star that is separated from the primary pair by a distance of 2.96 AU, giving the system a mutual orbital period of 681 days. Algol is about 92.8 light-years from the Sun, but about 7.3 million years ago it passed within 9.8 light-years of the Solar System[39] and its apparent magnitude was about −2.5, which is considerably brighter than the star Sirius is today. Reflection effect between the primary and secondary stars in Algol has been imaged using Doppler Tomography of this kind be. Class of eclipsing variable, known as Algol variables solved by the magnetic fields of the a and what kind of star system is algol... 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