Each of the two stars can appear brighter or fainter than the other in different passbands. It just outshines its neighbour Caph in Cassiopeia, Epsilon Centauri in Centaurus, and Dschubba in Scorpius.Įven though the German astronomer Johann Bayer assigned it the designation Alpha, Schedar appears as bright as Caph, Beta Cassiopeiae. It is about as bright as Alphecca in the constellation Corona Borealis, Suhail in Vela, Sadr in Cygnus, Eltanin in Draco, and Mintaka in Orion. On average, Schedar is the 71st brightest star in the sky. It also appears inverted when seen from the northern hemisphere during the winter months. From locations south of the equator, the W appears inverted (if it rises at all). Schedar forms Cassiopeia’s prominent W pattern with Caph (Beta Cassiopeiae), Gamma Cassiopeiae, Ruchbah (Delta Cassiopeiae), and Segin (Epsilon Cassiopeiae). Other stars in this group are Capella in the constellation Auriga, Vega in Lyra, Deneb in Cygnus, Mirfak in Perseus, Alioth, Dubhe and Alkaid in Ursa Major, Polaris and Kochab in Ursa Minor, and Eltanin in Draco. It is one of the 11 northern navigational stars with a declination between 30° N and 90° N. As part of Cassiopeia’s W, Schedar is one of the easiest stars to find. Navigational stars have a special status in the field of celestial navigation because they are bright and easy to identify. It is the only navigational star in Cassiopeia. Schedar is one of the 58 bright stars selected for use in navigation. However, no evidence of variability has been detected in the past century. Schedar was reported to be a variable star in the 19th century and is still often listed as a suspected variable. Schedar (Alpha Cassiopeiae), image: Wikisky This translates into a physical radius of 0.393 astronomical units, or about 42 solar radii. Schedar’s angular diameter was measured in 1998, yielding a value of 5.62 ± 0.06 milliarcseconds for the limb-darkened diameter. With a projected rotational velocity of 21 km/s, it takes about 102 days to complete a rotation. The star’s estimated age is between 100 and 200 million years. With a surface temperature of 4,530 K, it shines with 676 solar luminosities. The star is 4-5 times more massive than the Sun and has a radius about 42.1 times solar. Schedar has the stellar classification K0IIIa, indicating a giant star appearing orange in colour. All three stars are part of Cassiopeia’s familiar W asterism. 1.6 – 3.0) and it just barely outshines Caph (Beta Cassiopeiae, mag. It is sometimes outshined by its variable neighbour Gamma Cassiopeiae (mag. With an apparent magnitude of 2.240, it is the brightest or second brightest star in Cassiopeia. It lies at a distance of 228 light years from Earth. Schedar, Alpha Cassiopeiae (α Cas) is an orange giant star located in the constellation Cassiopeia.
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