INTRO

by Stanislav Tsanev and Momchil Rogelov
Advisor: Vanya Angelova

Algol belongs to Perseus, a constellation of the Northern Hemisphere. It is the second brightest star, and therefore, its name is Beta Persei. According to the legends, the Greek hero Perseus defeated Cetus using Medusa’s head. Algol lies in the position of Medusa’s eye, whose head is raised by Perseus. The star is interesting because its magnitude varies with time. Its name originates from the Arab "Ra's al Ghul", the Daemon’s Head. It is also sometimes referred to as “the devil’s eye” or “the blinking daemon”.

Algol’s variability was discovered by Geminiano Montanari, an Italian astronomer, in 1667. It was not until 1783 that the English scientist John Goodricke suggested the variations in magnitude were caused by eclipses of the bright component by a darker companion. He was also the first to determine that the period of variation was regular and to measure it. The binary nature of Algol was experimentally proved by a spectrographic analysis done by Hermann Carl Vogel in 1889. He found periodic Doppler shifts in the spectrum of the brighter star and an accompanying second spectrum, that of the darker star. Using spectroscopy, the two stars were determined to be of spectral class B8V and K2IV respectively for Beta Persei A and Beta Persei B.

In addition to those two, a third component, Beta Persei C, was discovered in spectral lines by Frank Schlesinger in 1912. Deviations in the movement of the system observed by Dean McLaughlin in 1934 and other scientists confirmed it.

Through spectroscopic and photometric analysis, the movement and relationships between the components of the system have been determined.