It lies at an approximate distance of 90 light years from Earth and has an apparent magnitude that varies between 2.12 and 3.4. Goodricke also discovered the periodic variation of Delta Cephei, the prototype for the Cepheid variable stars. What distinguishes Algol variables from, e.g. The bright stars of Cassiopeia can be used to star-hop to Mirfak, the brightest star in Perseus and the central star of the Alpha Persei Cluster, and then to Algol. Two nearby stars, Epsilon Persei (mag. 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. 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. Algol, Beta Persei (β Per) is a triple star system located in the constellation Perseus. Initially, the star system seemed to evolve in a manner that defied established beliefs about stellar evolution. Algol is a triple-star system which dims on a regular basis and when at its brightest it shines three times that as when it’s dimming. 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). star if the period, inclination, and radial velocity of each star is known. (Sirius has an apparent magnitude of -1.46.) Constellation: Perseus The star has been associated with demons, violence and death across different cultures: ghouls in the Arabic world, the Gorgon in Greek mythology, and Rōsh ha Sāṭān (Satan’s Head) in Hebrew folklore. The separation has to be pretty small for the odds to be good this will happen. 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. Temperature: 7,500 K. Each star has a teardrop-shaped surrounding region, now called the Roche lobe, which contains orbiting material that is gravitationally bound to the star. This is because our eyes, especially in low light conditions, cannot distinguish colour very well. Declination: +40°57’20.3280’’ 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. 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. Mass: 3.17 solar masses Algol is a known variable star, which waxes and wanes in brightness. Refer to Hoffman et al. Perseus and Caput Medusæ, plate 6 in Urania’s Mirror, a set of celestial cards accompanied by A familiar treatise on astronomy … by Jehoshaphat Aspin. 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 Algol 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. It revolves around the main binary pair every 1.85 years. Almach is the third star in the chain that leads from Alpheratz and the Great Square of Pegasus to Perseus. Algol is the best known variable star of its type, but there are countless other Algol variables known. The star is also known as Gorgona, Gorgonea Prima, Demon Star and El Ghoul. Beta Persei Aa1 and Aa2 form a binary pair. Today, Algol is the 61st brightest star in the sky at its brightest (mag. Distance: 90 light years (28 parsecs) Algol’s brightness is usually at magnitude 2.1, with 10-hour long eclipses occurring every 2.867328 days (2 days, 20 hours and 49 minutes), when the fainter Beta Persei Aa2 passes in front of Beta Persei Aa1 and the system’s magnitude drops to 3.4. Image: Dr Fabien Baron, Dept. The form of Algol C, however, is an artifact. You will also be asked to do a paper review of a journal article on some variable star classification or light curve related subject. 2.88) and Almach (mag 2.1) can be used for reference when watching the progress of the eclipses. of Astronomy, University of Michigan, Ann Arbor, MI 48109-1090. If we could, we would see that stars vary a great deal in the wavelengths of the light they produce. In 2003, the General Catalogue of Variable Stars listed more than 3,500, which was 9% of all known variables. 2.12). As they orbit each other, the stars pass in front of each other, causing eclipses. This animation was assembled from 55 images of the CHARA interferometer in the near-infrared H-band, sorted according to orbital phase. 2.23), the westernmost star of Orion’s Belt, Alphecca (Alpha Coronae Borealis, mag. that it is p… Radius: 1.73 solar radii