dimanche 5 octobre 2008

Perseus 11

α, 2.1, brilliant lilac and ashy.

Algenib, with the early variations of Algeneb, Elgenab, Genib, Chenib, and Alchemb, is from Al Janb, the Side, its present position on the maps; Chrysococca similarly called it Πλευρά Περσάους.
Another name, Marfak or Mirfak, the Elbow, sometimes written Mirzac, comes from the Arabians' Marfiḳ al Thurayya, thus qualified as being next to the Pleiades to distinguish it from the other elbow. But this may indicate a different representation of Perseus in their day, — a suspicion strengthened by the nomenclature of others of his stars, especially of ξ and ο.
Assemani alluded to a title on the Borgian globe, — Mughammid, or Muliammir, al Thurayya, the Concealer of the Pleiades, — which, from its location, may be for this star.
With γ, δ, and others it was the Chinese Tien Yuen, the Heavenly Enclosure.
Algenib never sets in the latitude of New York City, but just touches the horizon at its lower culmination. Its spectrum is of Secchi's second, or Solar, type, and the Potsdam observations indicate that the star is approaching our system at the rate of 6 1/2 miles a second.

the Gorgon's Head, a ghastly sight,
Deformed and dreadful, and a sign of woe.

Bryant's translation of the Iliad.
β, Spectroscopic binary and variable, 2.3 to 3.5, white.

Algol, the Demon, the Demon Star, and the Blinking Demon, from the Arabians' Raʼs al Ghul, the Demon's Head, is said to have been thus called from its rapid and wonderful variations; but I find no evidence of this, and that people probably took the title from Ptolemy. Al Ghul literally signifies a Mischief-maker, and the name still appears in the Ghoul of the Arabian Nights and of our day. It degenerated into the Alove often used some centuries ago for this star.
Ptolemy catalogued it as τῶν ἐν γοργονίῳ ὁ λαμπρός, "the bright one of those in the Gorgon's head," which Al Tizini followed in his Nāʼir, for, with π, ρ, and ω, it made up that well-known group, itself being the Gorgonea prima; the Γοργόνιον of Chrysococca, Gorgoneum Caput of Vitruvius [IX.4.2], Caput Gorgonis of Hyginus, and the Gorgonis Ora of Manilius.
With astronomical writers of three centuries ago Algol was Caput Larvae, the Spectre's Head. Hipparchos and Pliny made a separate constellation of the Gorgon stars as the Head of Medusa, this descending almost to our own day, although always connected with Perseus.
The Hebrews knew Algol as Rōsh ha Sāṭān, Satan's Head, Chilmead's Rosch hassatan, the Divels head; but also as Līlīth, Adam's legendary first wife, - We are indebted to the Talmudists for this story, which probably originated in Babylonia; and they added that, after Adam had separated from Līlīth and their demon children, Eve was created for him. Our Authorized Version renders the original word, in Isaiah xxxiv.14, by "screech owl"; the Revised Version, by "night-monster"; Cheyne adopts the Hebrew Lilith in the Polychrome Bible; and Luther's Bible had Kobold, but this corresponded to the Scottish Brownie and the English "Robin Goodfellow," — Shakespeare's "Puck." Saint Jerome's Vulgate translated it "Lamia," the Greek and Roman title for the fabled woman, beautiful above, but a serpent below, that Keats reproduced in his Lamia. -the nocturnal vampire from the lower world that reappeared in the demonology of the Middle Ages as the witch Lilis, one of the characters in Goethe's Walpurgis Nacht.
The Chinese gave it the gruesome title Tseih She, the Piled-up Corpses.
p333 Astrologers of course said that it was the most unfortunate, violent, and dangerous star in the heavens, and it certainly has been one of the best observed, as the most noteworthy variable in the northern sky. It "continues sensibly constant at 2.3 magnitude during 2 1/2 days, then decreases, at first gradually, and afterward with increasing rapidity, to 3.5 magnitude"; its light oscillations occupying about nine hours; its total period being stated as 2 days 20 hours 48 minutes 55 seconds. Al Sufi, a good observer for his day, yet strangely making no allusion to its variability, called it a 2nd‑magnitude; and the phenomenon was first scientifically noted by Montanari during several years preceding 1672. This was confirmed by Maraldi's observations of 1694, and, later, by those of the Saxon farmer Palitsch, -Palitsch also was famous for his discovery of Halley's comet on Christmas night, 1758. - but its approximate period seems to have been first announced by Goodricke in 1782, who even then advanced the theory of a dark companion revolving around it with immense velocity, which periodically cut off its light. This, reaffirmed by Pickering in 1880, was made certain by the spectroscope in the hands of Vogel of Potsdam in 1889. Chandler thinks that there must exist another invisible body larger than either Algol or its companion, around which both revolve in a period of 130 years; but Tisserand has shown that the phenomenon on which Chandler bases this opinion can be explained in a different and simpler way. Its name is used for the type indicating short-period variables whose changes may be explained by this theory of "eclipses." Of these seventeen are now known.
Although classed among the white stars with a Sirian spectrum, Al Sufi wrote of it as red, which Schmidt confirmed as seen by him at Athens for a short time in 1841. It seems to be approaching us at the rate of about a mile a second; and is estimated as a little more than a million miles in diameter.
When on the meridian Algol is almost exactly in the zenith of New York City. This is at nine o'clock in the evening of the 23d of December.

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