En cours

Cassiopeia is a constellation in the northern sky, named after the vain queen Cassiopeia in Greek mythology, who boasted about her unrivalled beauty. Cassiopeia was one of the 48 constellations listed by the 2nd-century Greek astronomer Ptolemy, and it remains one of the 88 modern constellations today. It is easily recognizable due to its distinctive 'W' shape, formed by five bright stars. It is opposite the Big Dipper. In northern locations above latitude 34ºN it is visible year-round and in the (sub)tropics it can be seen at its clearest from September to early November. Even in low southern latitudes below 25ºS it can be seen low in the North.

The next seven brightest stars in Cassiopeia are also all confirmed or suspected variable stars, including 50 Cassiopeiae which was not given a Greek letter by Bayer and is a suspected variable with a very small amplitude. Zeta Cassiopeiae is a suspected slowly pulsating B-type star. Eta Cassiopeiae is a spectroscopic binary star with a period of 480 years, and a suspected RS Canum Venaticorum variable. The primary is a yellow-hued star of magnitude 3.5 and the secondary is a red-hued star of magnitude 7.5. The system is 19 light-years from Earth. Kappa Cassiopeiae is a blue supergiant of spectral type BC0.7Ia that is some 302,000 times as luminous as the Sun and has 33 times its diameter.[23] It is a runaway star, moving at around 2.5 million mph relative to its neighbors (1,100 kilometers per second).[24] Its magnetic field and wind of particles creates a visible bow shock 4 light-years ahead of it, colliding with the diffuse, and usually invisible, interstellar gas and dust. The dimensions of the bow shock are vast: around 12 light-years long and 1.8 light-years wide.[25] Theta Cassiopeiae, named Marfak, is a suspected variable star whose brightness changes by less than a tenth of a magnitude. Iota Cassiopeiae is a triple star 142 light-years from Earth. The primary is a white-hued star of magnitude 4.5 and an α2 Canum Venaticorum variable, the secondary is a yellow-hued star of magnitude 6.9, and the tertiary is a star of magnitude 8.4. The primary and secondary are close together but the primary and tertiary are widely separated. Omicron Cassiopeiae is a triple star and the primary is another γ Cassiopeiae variable.

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Cassiopeia is a constellation in the northern sky, named after the vain queen Cassiopeia in Greek mythology, who boasted about her unrivalled beauty. Cassiopeia was one of the 48 constellations listed by the 2nd-century Greek astronomer Ptolemy, and it remains one of the 88 modern constellations today. It is easily recognizable due to its distinctive 'W' shape, formed by five bright stars. It is opposite the Big Dipper. In northern locations above latitude 34ºN it is visible year-round and in the (sub)tropics it can be seen at its clearest from September to early November. Even in low southern latitudes below 25ºS it can be seen low in the North.

The next seven brightest stars in Cassiopeia are also all confirmed or suspected variable stars, including 50 Cassiopeiae which was not given a Greek letter by Bayer and is a suspected variable with a very small amplitude. Zeta Cassiopeiae is a suspected slowly pulsating B-type star. Eta Cassiopeiae is a spectroscopic binary star with a period of 480 years, and a suspected RS Canum Venaticorum variable. The primary is a yellow-hued star of magnitude 3.5 and the secondary is a red-hued star of magnitude 7.5. The system is 19 light-years from Earth. Kappa Cassiopeiae is a blue supergiant of spectral type BC0.7Ia that is some 302,000 times as luminous as the Sun and has 33 times its diameter.[23] It is a runaway star, moving at around 2.5 million mph relative to its neighbors (1,100 kilometers per second).[24] Its magnetic field and wind of particles creates a visible bow shock 4 light-years ahead of it, colliding with the diffuse, and usually invisible, interstellar gas and dust. The dimensions of the bow shock are vast: around 12 light-years long and 1.8 light-years wide.[25] Theta Cassiopeiae, named Marfak, is a suspected variable star whose brightness changes by less than a tenth of a magnitude. Iota Cassiopeiae is a triple star 142 light-years from Earth. The primary is a white-hued star of magnitude 4.5 and an α2 Canum Venaticorum variable, the secondary is a yellow-hued star of magnitude 6.9, and the tertiary is a star of magnitude 8.4. The primary and secondary are close together but the primary and tertiary are widely separated. Omicron Cassiopeiae is a triple star and the primary is another γ Cassiopeiae variable.

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Description

The other prominent open clusters in Cassiopeia are NGC 457 and NGC 663, both of which have about 80 stars. NGC 457 is looser, and its brightest member is Phi Cassiopeiae, a white-hued supergiant star of magnitude 5.0. The stars of NGC 457, arrayed in chains, are approximately 10,000 light-years from Earth. NGC 663 is both closer, at 8200 light-years from Earth, and larger, at 0.25 degrees in diameter.

Galerie