Gamma Cassiopeiae was one of the many stars used as to calibrate the gyroscopes aboard Apollo spacecraft. Occasionally, though, Gamma Cassiopeiae is referred to informally as “Navi.” This recent nickname came out of the Apollo Program of the 1960/70s. The Gamma Cassiopeiae label we use today is strictly utilitarian, part of Johann Bayer’s star-cataloging efforts of the 1600s. However, there is little existing mythology involving the star Gamma Cassiopeiae specifically, and the star oddly lacks a traditional Greek or Arabic name, and doesn’t have a proper name at all. in Greek mythology, Cassiopeia is a queen whose boasts about her beauty land her and her royal family in big trouble. In some Chinese mythology, the W is incorporated in a chariot driver constellation, with Gamma Cassiopeiae representing the whip (“Tsih” in Chinese). In Greek myths, Queen Cassiopeia was the rather vain mother of Andromeda, and some star map illustrations portray the constellation as the queen seated in a W-shape chair, looking at herself in a mirror. The lowercase e stands for emission lines from hydrogen, first noted by Father Angelo Secchi in the 19th century. Gamma Cassiopeiae is classified as a Be star, different from ordinary B-class stars. The star’s brightness changes as matter is flung from the star - hence the name eruptive variable. While distance prevents us from directly observing the disk, we can nevertheless determine its existence through spectroscopy. This material then forms a disk of orbiting material. But Gamma Cassiopeiae spins much faster, some 400 kilometers per second (900,000 mph), and the resulting colossal forces are strong enough to occasionally dislodge matter from the star. Gamma Cassiopeiae rotates at a high speed - so fast that its shape is distorted, similar to the effects seen on Vega, Regulus, and Altair. But those changes aren’t predictable, so what’s going on? Sometimes Gamma Cassiopeiae dims to 3rd-magnitude, while during other periods it shines as brightly as magnitude 1.6, as it did in the 1930s. That star is Gamma Cassiopeiae, the middle point in the W shape of Cassiopeia. If you’d like to seek out one of these for yourself, there’s a bright and easy-to-find eruptive variable in the northern sky - and you’ve probably seen it many times without knowing it. Gamma Cassiopeiae is the middle point of the "W"-shape constellation. Cassiopeia hangs above the glow of Northern Lights. Other stars are more dramatic, including a class of irregularly changing stars known as eruptive variables. Even the Sun is slightly variable, brightening and dimming over a roughly 11-year period by 0.1%. Variable stars are a large class of objects that amateur and professional astronomers have long chased for both fun and science. Varies currently about 2.15 (historically 1.6–3.0)Ī variable star is a star that fluctuates in brightness over a period of time, perhaps less than a day, or maybe weeks, months, or years.
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