Sections

Catalogues

Show the direction and distance to this object on the Galactic Map.

Proper Names	Rasalgethi, Ras Algethi
Bayer Designation	Alpha¹ Herculis
Flamsteed Number	64 Herculis
HR (BSC)	6406
HD	156014
Constellation	Hercules
Right Ascension	17h 14m 39s
Declination	+14° 23' 25"
Distance	382 light years 117 parsecs
Magnitude	Apparent: +3.3 Absolute: -2.0
Spectral Class	M5 Red Supergiant
Optimum Visibility	June / July
Notes	The primary star of the Ras Algethi system is a swollen red giant with a diameter some four hundred times that of the Sun, which pulsates in a semiregular pattern and shows considerable variability over time. It is part of a triple system, orbited at a distance of some 500 AU by a binary pair consisting of a yellow giant and a bright yellow dwarf star.

The brightest star in Hercules has an Arabic name meaning 'head of the kneeling man'. The primary in this distant and complex system is a very massive red giant, but orbiting this is a closer double star that shines with a yellow-green light.

v2.1g