lundi 29 septembre 2008

Cetus 6

γ, Double, 3.5 and 7, pale yellow and blue.

Al Kaff al Jidhmah is the Arabs' name for the whole group marking the Whale's head, but in modern lists is exclusively applied to this star.
The components are 2ʺ.5 apart, at a position angle of 290°.
ε, of the 5th magnitude, with π, was a part of the Ostrich's Nest that mainly lay in Eridanus; and, with π, ρ, and σ, also was Al Sufi's Al Sadr al Ḳaiṭos, the Whale's Breast.
Notwithstanding its lettering, it is the faintest of these four stars.
ε, ρ, and σ were the Chinese Tsow Kaou, Hay n Straw.

ζ, 3.9, topaz yellow,

is Baten Kaitos, the Arabian Al Baṭn al Ḳaiṭos, the Whale's Belly, although the star is higher up the body. The Alfonsine Tables had Batenkaiton and Batenel Kaitos; and Chilmead, Boten.
In astrology it portended falls and blows.
It forms, with the 5th‑magnitude χ, a very coarse naked-eye double; and itself has a 7 1/2‑magnitude companion 3ʹ6ʺ distant.
η, 3.6, yellow.

Deneb and Dheneb are names for this star, especially in English lists, maps, and globes; but incorrectly, as η, on the Heis Atlas, lies at the base of the tail, and in Bayer's and Argelander's on the Monster's flank, while there are two others, β and ι, so named in the proper location. Still, although a misnomer, the title seems to be generally recognized. The Century Cyclopedia extends it as Deneb Algenubi. This error in name has led to another, for the star has been mistaken for the Rana Secunda of the Arabs, the Second Frog, the Arabs' Al Ḍifdiʽ al Thānī, — β Ceti.

ι, 3.6, bright yellow,

is another Deneb Kaitos to which the Arabians added Al Shamāliyy as being in the Northern branch of the tail, although Heis places it in the Southern. From this Arabic adjective the Standard Dictionary very unsatisfactorily gives Schemali simply as the star's title. With η, θ, ν, τ, and stars in the modern Fornax, it made up the Chinese asterism Tien Yuen, Heaven's Temporary Granary.
λ, of about 4 1/2 magnitude, is occasionally called Menkar, and, as it exactly marks the Nose of Cetus, the title would seem to be more appropriate than it is to α; but it was applied by the Arabs to both.
ο, Variable, 1.7 to 9.5, flushed yellow.

Mira, Stella Mira, and Collum Ceti are all titles for this Wonderful Star in the Whale's neck, the show object in the heavens as a variable of long period and typical of its class.
It was first noticed as a 3d‑magnitude on the 13th of August, 1596, and again on the 15th of February, 1609, by David Fabricius, an amateur astronomer and disciple of Tycho Brahē; but its true character was not ascertained till 1638 by Phocylides Holwarda of Holland, — the first established record of a variable star.
Bayer lettered it in 1603 as of the 4th magnitude, evidently at a time of its diminished brilliancy and without knowledge of its variability; Hevelius, having observed it from 1659 to 1682, inserted it in his Prodromus as the Nova in Collo Ceti; and Flamsteed, numbering it 68, described it as in pectore nova and of the 6th magnitude on the 18th of October, 1691, and again on the 28th of September, 1692.
"This was singular in its kind till that in Collo Cygni was discovered; and the attention it excited among astronomers is detailed in the Historiola Mirae Stellae" of Hevelius in 1662; thus virtually naming it and "commemorating the amazement excited by the detection of stellar periodicity."
Its period, fixed by Bouillaud in 1667 as 333 days, is now given as 331, but this is subject to extreme irregularities, — at various times it has not been seen at all with the naked eye for several years consecutively, — and its maxima and minima are even more irregular. While it has been known almost to equal Aldebaran in its light, as it did under Herschel's observations on the 6th of November, 1779, Chandler gives its maximum as from 1.7 to 5, and its minimum from 8 to 9.5. It thus sometimes sends out at its maximum fifteen hundredfold moderate light than at its minimum, and "after three centuries of notified activity gives no sign of relaxation." It is generally at its brightest for about a fortnight; the increase occupying about seven weeks and the decrease about three months. The maximum of 1897 occurred about the 1st of December, when it was a little below the 3d magnitude.
Sir William Herschel wrote of it in 1783 as being of a deep garnet color like μ Cephei.
The spectrum is of Secchi's 3d type, with extremely brilliant hydrogen lines at the time of maximum.
Mira lies almost exactly on the line joining γ and ζ, a little nearer the former star.
ϕ1, ϕ2, ϕ3, and ϕ4, 5th- to 6th‑magnitude stars, were the Arabs' Al Nithām. In China they were Tien Hwan, Heaven's Sewer. It was near these that Harding of Lilienthal discovered the minor planet Juno, on the 2d of November, 1804, the 3d of these objects found.
c and y, small stars near τ, were the Chinese Foo Chih, the Ax and Skewer.

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