The seventh brightest star in the night sky, ranking just behind Capella, Rigel is a blue supergiant star in the constellation of Orion. It is truly enormous, with a diameter 60 times greater, and an overall luminosity 66,000 times greater than our sun, but at 7751 light years away its apparent magnitude falls below that of smaller, closer stars such as the Summer Triangle of Vega, Capella and Arcturus. Its surface temperature is approximately 11,000 degrees Kelvin, twice as hot as the sun.

Rigel means "the foot" in Arabic, and represents the left foot of Orion. Orion was stung on this foot by a scorpion sent by Gaia, the Earth goddess, after he boasted that he would exterminate all the animals of the world. Interestingly, in the Norse mythology Rigel represents one toe of Orwandil, the other of which was broken off by Thor and thrown into the sky to become the star Alcor of Ursa Major. In earlier Arabic times Rigel was known as Ra'i al Jauzah, the Herdsman of Jauzah, who herded camels represented by the stars Betelgeuse, Bellatrix, Mentaka and Saiph.

Rigel actually has two younger companion stars, a binary system composed of Rigel B and Rigel C, orbiting at between 9 and 10 arc seconds from Rigel itself. The smaller stars are in their hydrogen fusion phase, while Rigel is dying, having entered its helium fusion phase. Stars of Rigel's size almost invariably end in a supernova, but there is an outside chance that it might shed enough mass to collapse into an oxygen/neon white dwarf without exploding. Rigel is a very young star (perhaps as little as 1 million years old) when compared with our sun, which is approximately 4.6 billion years old and only halfway through its life cycle. It is burning its energy at such a ferocious rate that it is likely to go supernova at some point in the next couple of million years.

1. Several different sources on the Web give Rigel's distance from Earth as anything between 700 and 1000 light years. I have chosen a figure that seemed to crop up more often, but if anyone has a definitive figure and source, please /msg me and I will include it here.
References and further reading:

Ri"gel (?), n. [Ar. rijl, properly, foot.] Astron.

A fixed star of the first magnitude in the left foot of the constellation Orion.

[Written also Regel.]


© Webster 1913.

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