mercredi 1 octobre 2008

Andromeda 13

α, Double, magnitudes 2.2 and 11, white and purplish.

Alpheratz, Alpherat, and Sirrah are from the Arabians' Al Surrat al Faras, the Horse's Navel, as this star formerly was associated with Pegasus, whence it was transferred to the Woman's hair; and some one has strangely called it Umbilicus Andromedae. But in all late Arabian astronomy taken from Ptolemy it was described as Al Rās al Marʼah al Musalsalah, the Head of the Woman in Chains.
Aratos designated it as ξῦνός ἀστήρ, i.e., common to both constellations, and it is still retained in Pegasus as the δ of that figure, although not in general use by astronomers.
In England, two centuries ago, it was familiarly known as Andromeda's Head.
With β Cassiopeiae and γ Pegasi, as the Three Guides, it marks the equinoctial colure, the prime meridian of the heavens; and, with γ Pegasi, the eastern side of the Great Square of Pegasus.
In the Hindu lunar zodiac this star, with α, β, and γ Pegasi, — the Great Square, — constituted the double nakshatra, — the 24th and 25th, — Pūrva and Uttara Bhādrapadās, the Former and the Latter Beautiful, or Auspicious, Feet; also given as Proshthapadās, Footstool Feet; while Professor Weber of Berlin says that it was Praṭishthana, a Stand or Support, which the four bright stars may represent.
With γ Pegasi, the determinant star, it formed the 25th sieu Pi, or Peih, a Wall or Partition, anciently Lek, and the manzil Al Fargu, from Al Farigh al Muʼaḣḣar, the Hindmost Loiterer; or, perhaps more correctly, the Hind Spout of the Water-Jar, for Kazwini called it Al Farigh al Thānī, the Second Spout; a Well-mouth and its accompaniments being imagined here by the early Arabs.
The Persian title for this lunar station, Miyan; the Sogdian, Bar Farshat; the Khorasmian, Wabir; and the Coptic, Artulosia, all have somewhat similar meanings.
In astrology α portended honor and riches to all born under its influence. It comes to the meridian — culminates — at nine o'clock (All culminations mentioned in this work are for this hour. ) in the evening of the 10th of November.
β, 2.3, yellow.

Mirach was described in the Alfonsine Tables of 1521 as super mirat, from which has been derived its present title, as well as the occasional forms Mirac, Merach, Mirar, Mirath, Mirax, etc.; mirat probably coming from the 1515 Almagest's super mizar, the Arabic miʼzar, a girdle or waist-cloth. Scaliger, the great critical scholar of the 15th century, adopted this Mizar as a title, and Riccioli followed him in its use, thus confounding the star with ζ Ursae Majoris. The Mirae of Smyth doubtless is a typographical error, although Mirae had appeared in Chilmead's Treatise This book, a Learned Treatise on Globes, was a translation by Master John Chilmead, of Oxford, of two early Latin works by Robert Hues and Io. Isa. Pontanus. It is an interestingly quaint description of the celestial globes of that and the preceding century, with their stellar nomenclature, of 1639 for the same word applied to β Ursae Majoris.
Hipparchos seems to refer to it in his ζώνη; and, synonymously, some have termed it Cingulum; others, Ventrale, from its former position in the figure, although now it is on the left hip. In later Arabian astronomy it marked the right side of Andromeda, and so was known as Al Janb al Musalsalah, the Side of the Chained Woman. β appeared in very early drawings as the lucida of the northern of the two Fishes, and marked the 26th manzil Al Baṭn al Ḥūt, the Belly of the Fish, or Al Ḳalb al Ḥūt, the Heart of the Fish; and the corresponding sieu Goei, or Kwei, the Man Striding, or the Striding Legs, anciently Kwet. In this location it was AI Risḣā, the Band, Cord, Ribbon, or Thread, as being on the line uniting the Fishes; but this title now belongs to α Piscium.
Brown includes it, with υ, φ and χ Piscium, in the Coptic lunar station Kuton, the Thread; and Renouf, in Arit, an asterism indigenous to Egypt. It lies midway between α and γ, about 15º distant from each; and in astrology was a fortunate star, portending renown and good luck in matrimony.
γ, Binary, — and perhaps ternary, 2.3, 5.5, and 6.5. orange, emerald, and blue.

This is Alamac in the Alfonsine Tables and 1515 Almagest; Riccioli's Alamak; Flamsteed's Alamech; now Almach, Almak, Almaack, and Almaac or Almaak; all from Al ʽAnaḳ al ʽArḍ, a small predatory animal of Arabia, similar to a badger, and popularly known there as Al Barīd. Scaliger's conjecture that it is from Al Mauk, the Buskin, although likely enough for a star marking the left foot of Andromeda, is not accepted; for Ulug Beg, a century and a half previously, as well as Al Tizini (The catalogue of this author, Muḥammād abu Bekr al Tizini al Muwakkit, was published at Damascus in 1533 with 302 stars, and from its long list of purely Arabic star-names was regarded as worthy of translation and republication by Hyde, in 1665, with the original text. The muwakkit of his title indicates that he was shaykh of the grand mosque. ) and the Arabic globes before him, gave it the animal's title in full. But the propriety of such a designation here is not obvious in connection with Andromeda, and would indicate that it belonged to very early Arab astronomy.
Bayer said of it, perperam Alhames, an erroneous form of some of the foregoing. Riccioli8 also mentioned this name, but only to repudiate it.
Muhammād al Achsasi ( The Arabic manuscript of this author, with its star-list of about the year 1650, has been reviewed by Mr. E. B. Knobel in the Monthly Notices of the Royal Astronomical Society for June, 1895. It contains 112 stars, perhaps taken from Al Tizini's catalogue of the preceding century. The Achsasi of his title was from the village of similar name in the Fayūm, doubtless his birthplace; and, like Tizini, he was shaykh of the grand mosque in Cairo, where his work was written. ) al Muwakkit designated γ as Al Ḣāmis al Naʽāmāt, his editor translating this Quinta Struthionum, the 5th one of the Ostriches; but I have not elsewhere seen the association of these birds with this constellation.
Hyde gives another Arabian designation for γ as Al Rijl al Musalsalah, the Woman's Foot.
In the astronomy of China this star, with others in Andromeda and in Triangulum, was Tien Ta Tseang, Heaven's Great General. Astrologically it was honorable and eminent.
Its duplicity was discovered by Johann Tobias Mayer of Göttingen in 1778; and Wilhelm Struve, (Struve was the first director of the Russian National Observatory at Poulkowa, where he was succeeded by his son Otto; and two of the grandsons bear names already celebrated in astronomy.) in October, 1842, found that its companion was closely double, less than 1″ apart at a position angle of 100°, and probably binary. The two larger components are 10″.4 apart with a position angle of 63°.3. The contrast in their colors is extraordinarily fine. William Herschel wrote of it in 1804:
This double Star is one of the most beautiful Objects in the Heavens. The striking difference in the colour of the two Stars suggests the idea of a Sun and its Planet, to which the contrast of their unequal size contributes not a little; but Webb thought them stationary.
It is readily resolved by a 2 1/4‑inch glass with a power of forty diameters, and it seems singular that its double character was not sooner discovered.
From its vicinity radiate the Andromedes II, the Bielid meteors of November, so wonderfully displayed on the 27th of that month in 1872 and 1885, and on the 23d in 1892, and identified by Secchi and others with the celebrated comet discovered by Biela in 1826, which, on its return in 1832, almost created a panic in France. The stream completes three revolutions in about twenty years, although subject to great perturbations from Jupiter, and doubtless was that noticed on the 7th of December, 1798, and in 1838. These objects move in the same direction as the earth, and so with apparent slowness, — about ten miles a second, — leaving small trains of reddish-yellow sparks. The radiant, lying northeast from γ, is remarkable for its extent, being from 7 to 10 degrees in diameter. The Mazapil iron meteorite which fell in northern Mexico on the 27th of November, 1886, has been claimed "as being really a piece of Biela's comet itself."

Aucun commentaire: