More Than You Ever Wanted to Know About the Algol System

by Gargoyle Sox
gargoylesox@juno.com

5/31/99

Okay, first off, a binary system is a type of star that is actually two stars
that orbit closely around each other. Algol is a specific type of binary,
called an eclipsing binary star. These are very interesting because they
orbit each other in such a way that it can be viewed from earth.
Periodically, one star will appear to pass in front of the other, causing a
minor eclipse in the night sky. If you watch an eclipsing binary night after
night for a while (sometimes weeks, sometimes months or more), you can
actually notice the star become darker and then brighter when this happens.
For a star as bright as Algol, you don't even need a telescope to see the
change.

Algol (the name is Arabic for "demon star"), is an excellent example of an
eclipsing binary system because it has a period of about 2.87 days. This
means that it eclipses about once every three nights. At mideclipse (when
one star is completely in front of the other), it drops sharply in
brightness. This lasts for about 2 hours, and it takes roughly another 4
hours for it to get back to it's brightest again.

Algol should be easy to locate and view from almost anywhere in the northern
hemisphere. You can observe the entire eclipse process in one night when the
eclipse itself occurs around midnight or (preferably) later.

Information taken from "Astronomy: The Evolving Universe" eighth edition, by
Michael Zeilik

From Admiral whats-his-name:

Algol is also known as Beta Persei, the Medusa's Head in the
constellation Perseus. This fixed star was considered by the Ancients
as "the most evil star in the heavens." 

The Hebrews named Algol "Rosh ha Sitan" Satan's Head. The Chinese named
it "Tseih She" the Piled-up Corpses. The Ancient Arabian astrologers
gave it names such as the Demon, The Demon's Head, and the Blinking
Demon (due to Algol's binary eclipse every 68+ hours). 

Algol is a relatively close star to our sun, at a distance of only 115
light years. The total luminosity of the double star system is on the
order of 140 times that of the sun; when comparing the mass of both
stars in the Algol system to the sun, we find that the smaller of the
two stars is only .86 times the mass of the sun, while the larger star
is 4.5 times more massive.