Alpha Herculis

Ras Algethi or Rasalgethi (Arabic رأس الجاثي, DMG ra ʾ s al - ǧāṯī, head of the kneeling ' ) is the third brightest star in the constellation Hercules. In astronomy, he is referred to as α Herculis or short α production. The proper name Ras Algethi comes from a translation of the Almagest and was taken over in 1438 by John of Gmunden.

Ras Algethi is about 382 light-years away from Earth ( Hipparcos database). It involves a resolvable in small scopes double star.

The main star, a yellow-red giant star of spectral type M5, is a semi- regular variable star of type SRc whose apparent brightness like with a period of 125 days between 3.1 and 4.2 may fluctuate. He radiates strongly in the infrared.

The at an angular distance of 4 ", 7 at position angle 107 ° ( J2000.0 ) lying companion is a 5.4 like a bright star of spectral type F8. For a round the system requires about 3600 years.