Iota Aurigae
A K-type giant star in Auriga, also known as Hassaleh.
Iota Aurigae is a star in the northern constellation of Auriga, with the Bayer designation ι Aurigae. It has the official proper name Hassaleh, approved by the IAU Working Group on Star Names, and is bright enough at apparent visual magnitude 2.7 to be readily visible to the naked eye. Parallax measurements place it roughly 450 light-years from the Sun, and it is drifting further away with a radial velocity of +18 km/s.
- Constellation
- Auriga
- Apparent magnitude
- 2.7
- Distance
- ~450 light-years (140 parsecs)
- Spectral type
- K3 II–III
- Radial velocity
- +18 km/s
- Proper name
- Hassaleh
Lore & Background
Iota Aurigae bears the traditional name Al Kab, short for Kabdhilinan, from the Arabic phrase meaning 'the ankle of the rein holder (charioteer)'. Under the name Alkab, this star was used as a marker on the astrolabe described by Geoffrey Chaucer in his Treatise on the Astrolabe in 1391. The novel name Hassaleh appeared in Antonín Bečvář's 1951 atlas; its origin and meaning have not been discovered despite extensive search, and no connection to any language has been found. In Chinese, it is known as 五車一, meaning 'the First Star of the Five Chariots'.
Reader's Guide
Iota Aurigae is significant as a stable anchor point for stellar classification; since 1943, its spectrum has served as one of the reference standards by which other stars are classified. With a spectral type of K3 II–III, it is an evolved hybrid giant star, cooler than the Sun at an effective temperature of 4,160 K, giving it an orange hue. It is a weak X-ray emitter, with emission likely from transient plasma loops in its outer atmosphere at about 3 million K. The star is a suspected variable, and in 2007, Reffert et al. announced the detection of two substellar objects in 2:1 resonance, possibly brown dwarfs with orbital periods of about 2 and 4 years, though as of 2008 the detection remained unconfirmed. Hekker et al. (2008) listed significant radial velocity variations at periods of 767 and 1586 days, and the star may instead be an oscillating star undergoing non-radial pulsations with a period of about four years. Its legacy lies in its role in classification and the ongoing uncertainty about its companions.
Did You Know?
- Iota Aurigae has the official proper name Hassaleh, approved by the IAU Working Group on Star Names.
- Its spectrum has been a stable anchor point for classifying other stars since 1943.
- In 2007, two possible brown dwarf companions were announced in 2:1 resonance, but the detection remained unconfirmed as of 2008.
- The star may instead be an oscillating star undergoing non-radial pulsations with a period of about four years.
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