Algol B

By: Manasa Gudavalli

Beta Persei B (Scientific Name), The Demon Star (Nickname)

Background Info

Star: A self-luminous celestial body consisting of a mass of gas held together by its own gravity in whichthe energy generated by nuclear reactions in the interior is balanced by the outflow of energy to thesurface, and the inward-directed gravitational forces are balanced by the outward-directed gas andradiation pressures.

Luminosity: the brightness of a star in comparisonwith that of the sun

Absolute Magnitude: brightness of a celestial object as it would be seen

Apparent Magnitude: brightness celestial object as it is actually measured from the earth


Mass: 0.79 Solar

Density: 3.54 Solar

Size Relative to Earth: 3.3 million times larger than Earth

Size Relative to Sun: 3 times as larger than Sun

Age: greater than 3×10^8 years

Color: orange-red

Temperature: 4,500 Kelvins

Luminosity: 3.4 Solar Luminosity

Absolute Magnitude: −0.15

Apparent Magnitude: 2.12

Stellar evolution stage : sub giant star

Distance From Earth: 93 light years

Distance From Sun: 92.8 light years

Spectral Classification: K2


  • discovered in 1667 by the Italian astronomer Geminiano Montanari
  • it was said to have been seen before - watch this video to learn about the Egyptians who found Algol earlier