jeudi 4 septembre 2008

Cassiopeia 2


Cassiopeia
The Queen or The Lady in the Chair



The Brighter Stars of Cassiopeia
Caph


Schedar


The Story
The Vanity of Cassiopeia

Queen Cassiopeia is the lovely, but vain queen and wife to King Cepheus of Ethiopia. Cassiopeia had the presumption to claim that she was even more lovely than the exquisite Nereids, the fifty sea nymphs who were the daughters of the gentle god Nereus, known as the Old Man of the Sea.
The Nereids' Revenge

Now the Nereid Amphitrite was the wife of Poseidon the God of the Sea. The Nereids begged Poseidon to punish the pride of Cassiopeia. This he did by sending the monster Cetus to ravage Ethiopia. To appease the god, King Cepheus had to offer his daughter Andromeda as a sacrifice to the monster, but the hero Perseus was able to slay the monster before it attacked Andromeda.
The Upside-down Queen

As an added punishment Cassiopeia was placed in the sky to revolve around the celestial pole forever, sometimes hanging upside down in undignified positions.


Caph
Beta Cassiopeiae



Distance (Light Years) 54.5 ± 0.5
Visual Magnitude 2.28
Color (B-V) 0.34

Names For This Star

This star is also known as Chaph, Kaff, or Al Sanam al Nakah.
The Arabs sometimes referred to the area of Cassiopeia as Kaff' al Hadib, "The Hand Stained with Henna." The usual name of the star, Caph, derives from this traditional name for the constellation.

Al Sanam al Nakah is "The Camel's Hump," reflecting another traditional version of Cassiopeia as a camel.

Description of the Star

Caph is a yellowish F2III-IV giant to subgiant star. The luminosity is 130 times that of the sun. The spectrum indicates that Caph is a binary star with an orbital period of 27 days, but there is little information available on the companion.
Caph is a variable star of Delta Scuti type as well. The brightness fluctuates by about 0.03 magnitudes with a period of 2.4 hours. See Burnham for a detail discussion of the Delta Scuti stars.


Schedar
Alpha Cassiopeiae



Distance (Light Years) 228.6 ± 9.1
Visual Magnitude 2.24
Color (B-V) 1.17

Names For This Star

Other names for the star are Shedir or Schedir, which, according to Allen probably derives from the Arabic Al Sadr, "The Breast. Alternatively the name may derive from the Persian name Shuter for the constellation.
Description of the Star

Schedar is an orange K0IIIa giant having a luminosity about 530 times that of the sun.

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