Algol is the best known variable star of its type, but there are countless other Algol variables known. The eclipsing binary pair is separated by only 0.062 astronomical units (AU) from each other, so close in fact that Algol A is slowly consuming the less massive Algol B by continually stripping off Algol B’s outer layers. Rotational velocity: 49 km/s When a star exceeds its Roche lobe, the material outside the lobe falls off into the companion star’s Roche lobe. Even though both components in the binary system formed at approximately the same time, the primary, more massive star in the system is still on the main sequence, while the less massive secondary component has evolved into a subgiant. Goodricke also discovered the periodic variation of Delta Cephei, the prototype for the Cepheid variable stars. Mirach, the middle star in the chain, is used to find the Andromeda Galaxy (M31) and Triangulum Galaxy (M33). 466. Beta Persei Aa1 and Aa2 form a binary pair. Temperature: 4,500 K, Spectral class:  A7m In 2003, the General Catalogue of Variable Stars listed more than 3,500, which was 9% of all known variables. Luminosity: 10 solar luminosities Distance: 90 light years (28 parsecs) You will also be asked to do a paper review of a journal article on some variable star classification or light curve related subject. star if the period, inclination, and radial velocity of each star is known. Absolute magnitude: 2.9 The phase of each image is indicated at the lower left. The star is also known as Gorgona, Gorgonea Prima, Demon Star and El Ghoul. Arthur: Star of Bootes, situated in the extension of the tail of Ursa Major. It is a triple star system composed of Beta Persei Aa1, a B-class main sequence star, Beta Persei Aa2, an orange subgiant, and Beta Persei Ab, a dimmer A-class star. Algol – the “demon” star The shape and timing of the eclipses gives the shape and size of the stars. This is because our eyes, especially in low light conditions, cannot distinguish colour very well. 2.09) in Orion and Kochab (Beta Ursae Minoris, mag. The more evolved secondary component was not always the less massive one, but the flow of material between the stars disturbed the normal evolution process and the originally more massive star (in this case the subgiant) lost much of its mass to the companion (the main sequence star). The paradox is explained with mass transfer, a phenomenon that is not uncommon in close binary stars. Constellation: Perseus 2.00), the second brightest star in Vela and one of the stars of the False Cross, and Almaaz (Epsilon Aurigae, mag. Initially, the star system seemed to evolve in a manner that defied established beliefs about stellar evolution. 2.08) in Ursa Minor, and it just outshines Muhlifain (Gamma Centauri, mag. Tidal distortions of Algol B giving it an elongated appearance are readily apparent. Their components are not so close together as to cause deformations in shape, which is the case with the other two types. The elongated appearance of Algol B and the round appearance of Algol A are real. Animation done on Mathematica by Simon Tyran (Yukterez, Vienna, 2.2.2016). It is the second brightest star in the constellation, after Mirfak, Alpha Persei. The Roche lobe represents the maximum a star can reach before it starts transferring material to the companion. 2.88) and Almach (mag 2.1) can be used for reference when watching the progress of the eclipses. that it is periodically eclipsed by a dimmer companion of almost the same size as itself. The star’s brightness can sometimes be seen falling and rising on the same night. Algol is relatively easy to find because it is located in the same area of the sky as Cassiopeia and the Great Square of Pegasus, between Cassiopeia’s W and the Pleiades. 2.23), the westernmost star of Orion’s Belt, Alphecca (Alpha Coronae Borealis, mag. Names and designations: Algol, Demon Star, Gorgona, Gorgonea Prima, El Ghoul, Beta Persei (β Persei, β Per), 26 Persei, HD 19356, HR 936, BD+40°673, SAO 38592, FK5 111, PPM 46127, GC 3733, HIP 14576, Spectral class:  B8V Since you also know the velocity (from Doppler shift) and orbital period, you can get the true scale of the system (including star sizes and masses). Algol currently lies at a distance of about 90 light years, but it was once much closer to the solar system. Algol is sometimes called Gorgonea Prima, in reference to the Gorgon Medusa. It is only slightly fainter than Denebola (Beta Leonis, mag. The star has been known since ancient times. Mirfak lies along the imaginary line extended from Gamma to Delta Cassiopeiae, and forms a triangle with Algol and the bright Almach, Gamma Andromedae. Luminosity: 182 solar luminosities that it is p… 2.23), the brightest star in Corona Borealis, Alsephina (Delta Velorum, mag. Algol and β Lyrae eclipsing binaries are differentiated by constant variation in the light curve outside of eclipses for the β Lyrae systems to the nearly constant brightness outside of eclipses of the Algol-type systems. It was one of the 15 Behenian stars, believed to be a source of astrological power and used in various rituals. of Astronomy, University of Michigan, Ann Arbor, MI 48109-1090. The classification of variable stars has been evolving for more than a century. As our understanding grows (and new types of objects are discovered), the classification criteria change. Algol The primary to the Algolian homeworld, a B-class star, is also known as Beta Persei in the old Terran Bayer classification system. Algol’s eclipses can be observed without a telescope. Two nearby stars, Epsilon Persei (mag. The other three stars, all located in the vicinity of Algol, are Pi Persei (π Persei, Gorgonea Secunda), a white main sequence star with an apparent magnitude of 4.7, Rho Persei (ρ Persei, Gorgonea Tertia), a reddish (class M) bright giant with a visual magnitude of 3.39, and Omega Persei (ω Persei, Gorgonea Quarta), an orange giant with a magnitude of 4.6. The studies of Algol challenged the theory that stars’ rate of evolution depends on their mass, meaning that, the greater the mass, the sooner the star will evolve off the main sequence. Tidal distortions also result in “gravity darkening” effects, whereby in a significant number of images of Algol B, the edge or “limb” of the image is actually brighter than the center. They are very close to each other (separated by only 0.06 astronomical units on average, or about 1/17 of the distance between the Earth and the Sun) and they revolve quite quickly. This is not an artistic representation, but rather is a true two-dimensional image with 1/2 milli-arcsecond resolution in the near-infrared H-band, reconstructed from data of the CHARA interferometer. Algol’s variability was first correctly explained by the English amateur astronomer John Goodricke in 1782, when he was only 18 years of age. 2.98), one of the brightest stars in the northern constellation Auriga. As they orbit each other, the stars pass in front of each other, causing eclipses. The 19th century French astronomer Édouard Roche was the first to explain the mechanics of accretion that occurs in close binary systems. Commonly known as the Demon Star, it is one of the best-known variable stars in the sky and a prototype for a class of eclipsing variable stars known as Algol variables. With a period of rotation of 69 hours, it is a double system that provides aspect of variable, but it is actually a binary eclipsante, i.e., their periodic variations in brightness are due to the mutual filing of its components. Algol (β Persei) is a triple-star system (Algol A, B, and C) in the constellation Perseus, in which the large and bright primary Algol A is regularly eclipsed by the dimmer Algol B every 2.87 days. ALGOL: Star b of the constellation of Perseus. 2.21) in Carina, and Suhail (Lambda Velorum, mag. Over time, the more massive and evolved star sheds much of its material, which is accreted by the companion, which then gradually becomes more massive. 2.17) in Centaurus, Aspidiske (Iota Carinae, mag. Declination: +40°57’20.3280’’ Algol was one of the first non-nova variable stars ever discovered. Age: 570 million years, Spectral class:  K0IV You will share this with the class as a brief description of the paper and its main points in the discussion forum. A similar mechanism is at play in other types of eclipsing binary stars. After observing the star to determine the period of its light variations, he suggested that Algol was what we now know as an eclipsing binary, i.e. Radius: 2.73 solar radii Observations of Algol led to the Algol paradox, which lay in the disparity between the mass and evolutionary stage of the two components of the eclipsing binary system. Refer to Hoffman et al. Algol’s proximity and mass may have caused an increase – albeit a small one – in the number of comets coming into the inner regions of the solar system.
2020 algol star classification