The Chinese Flying Corridor asterism is formed by Segin with Iota Cassiopeiae, Ruchbah (Delta Cassiopeiae), Theta Cassiopeiae, Nu Cassiopeiae, and Omicron Cassiopeiae. In Chinese astronomy, Segin is known as 閣道二 ( Gé Dào èr), the Second Star of Flying Corridor. The name was officially approved by the International Astronomical Union’s (IAU) Working Group on Star Names (WGSN) on September 5, 2017.Įpsilon Cassiopeiae once shared the name Ruchbah with Delta Cassiopeiae, which has kept the name. It may be a mistranscription of Seginus, another name with an uncertain origin, which now formally applies to Gamma Boötis.
The origin of the name Segin (pronunciation: /ˈsɛɡɪn/) is uncertain. Schedar, Caph, and Ruchbah are much closer to us, at 228, 54.7, and 99.4 light years respectively. Only Gamma Cassiopeiae is more distant, lying about 550 light years away. Even though it is the second most luminous of the W stars, Segin is the faintest because it is also the second most distant. Of the five stars, Gamma Cassiopeiae is the only one that is hotter (25,000 K), more massive (17 solar masses), more luminous (34,000 solar luminosities), and younger (8 million years) than Segin. It appears inverted during the northern winter months and when seen from locations south of the equator. The asterism appears as a W during the northern hemisphere spring and summer.
Segin forms Cassiopeia’s W with Ruchbah (Delta Cassiopeiae), Gamma Cassiopeiae, Schedar (Alpha Cassiopeiae) and Caph (Beta Cassiopeiae).