X-rays. However, difficulties remain with this mechanism, among which is that there are no disk dynamos known to exist in other stars, rendering this behavior more difficult to analyze. Companions Gamma Cassiopeiae has three faint companions, listed in double star catalogues as components B, C, and D. Star B is about 2 arc-seconds distant and magnitude 11, and has a similar space velocity to the bright primary, making it likely to be physically associated. Component C is magnitude 13, nearly an arc-minute distant, and is listed in Gaia Early Data Release 3 as having a very different proper motion and being much more distant than Gamma Cassiopeiae. Finally, component D, about 21 arc-minutes distant, is the naked-eye star HR 266 (HD 5408), itself a quadruple system. Gamma Cassiopeiae A, the bright primary, itself contains a spectroscopic binary with an orbital period of about 203.5 days and an eccentricity alternately reported as 0.26 and "near zero." The mass of the companion is believed to be about that of the Sun, but its nature is unclear. It has been proposed that it is a degenerate star or a hot helium star, but it seems unlikely that it is a normal star. Therefore, it is likely to be more evolved than the primary and to have transferred mass to it during an earlier stage of evolution. Additionally, Hipparcos data show a "wobble" with an amplitude of about 150 mas, that may correspond to the orbit of a third star. This star would have an orbital period of at least 60 years. Names The Chinese name Tsih, "the whip" (), is commonly associated with this star. The name however originally referred to Kappa Cassiopeiae, and Gamma Cassiopeiae was just one of four horses pulling the chariot of legendary charioteer Wangliang. This representation was later changed to make Gamma the whip. The star was used as an easily identifiable navigational reference point during space missions and American astronaut Virgil Ivan "Gus" Grissom nicknamed the star Navi after his own middle name spelled backwards. See also Iota Ursae Majoris, informally named Dnoces for astronaut Ed White Gamma Velorum, informally named Regor for astronaut Roger B. Chaffee References External links Philippe Stee's homepage: Hot and Active Stars Research Gamma Cassiopeiae and the Be Stars. A New Class of X-ray Star? Gamma Cas and Friends, Astronomy Picture of the Day, 2009 December 24 Cassiopeiae, Gamma B-type subgiants Cassiopeia