mardi 23 septembre 2008

Pegasus 7

That poetic steed,
With beamy mane, whose hoof struck out from earth
The fount of Hippocrene.

called thus in Germany, but Pégase in France and Pegaso in Italy, lies north of the Urn of Aquarius and the easternmost Fish, the stars of the Great Square inclosing the body of the Horse.
Mythologically he was the son of Neptune and Medusa, sprung by his father's command from the blood of the latter which dropped into the sea after her head had been severed by Perseus; and he was named either from Πηγαί, the Springs of the Ocean, the place of his birth, or from Πηγός, Strong. He was snowy white in color, and the favorite of the Muses, for he had caused to flow their fountain Pirene on Helicon,— or Hippocrene on the Acrocorinthus, — whence came one of the constellation titles, Fontis Musarum Inventor. Longfellow prettily reproduced in modern dress this portion of the story, in his Pegasus in Pound, where "this wondrous winged steed with mane of gold," straying into a quiet country village, was put in pound; but, finding his quarters uncomfortable, made his escape, and

To those stars he soared again.
. . . .
But they found upon the greensward
Where his struggling hoofs had trod,
Pure and bright a fountain flowing
From the hoofmarks in the sod.
He seems, however, to have come back to earth again, for he was subsequently caught by Bellerophon at the waters of his fountain, and ridden by him when he slew the Chimaera, helping in the latter's destruction. By this time classical legend had given him wings, and Bellerophon sought by their aid to ascend to heaven; but Jupiter, incensed by his boldness, caused an insect to sting the steed, which threw his rider, and, as Wordsworth wrote:
Bold Bellerophon (so Jove decreed
In wrath) fell headlong from the fields of air.
Pegasus then rose alone to his permanent place among the stars, becoming the Thundering Horse of Jove that carried the divine lightning.
Ptolemy mentioned the wings as well recognized in his day; and this has continued till ours, for the sky figure is now known as the Winged Horse, — a recurrence to Etruscan, Euphratean, and Hittite ideas, for the wings are clearly represented on a horse's figure on tablets, vases, etc., of those countries, where this constellation may have been known in pre-classical times. Indeed, it is said to have been placed in the heavens by the early Aryans to represent Asva, the Sun.
Early classical mythology did not associate the Horse with Perseus, although artists and authors do not seem to have remembered this, for the celebrated picture by Rubens in the Berlin Gallery shows the winged Pegasus held by a Cupid, while Perseus in full armor is unbinding Andromeda from the rocks, Cetus raging in the waters close by; and the late Lord Leighton left unfinished his Perseus on Pegasus at the cliffs of Joppa, with the Gorgoneion in his hand; while in Troilus and Cressida Shakespeare mentioned "Perseus' horse."
The Greeks called the constellation simply Ίππος, although Aratos added ἱερός, "divine," and Eratosthenes alluded to it as Πήγασος, but distinctly asserted that it was without wings, and until after middle classical times it generally was so drawn, although loose plumes at the shoulders occasionally were added. The figure was considered incomplete, a possible reason for this being given under Aries. Thus it was characterized as ἡμιτελής and ἡμίτομος, "cut in two," or as if partly hidden in the clouds; while Nonnus had Ἡμιφανής Λίβῦς ἴππος, the Half-visible Libyan Horse.

Thus the Equi Sectio used by Tycho and others for Equuleus would seem equally appropriate for this.
Euripides is said to have called it Melanippe, after a daughter of Chiron, also known as Euippe, changed by the goddess Artemis into a Black Mare and placed in the sky; but Bayer quoted from some later writer Menalippe. The Θεαιανα,º or Theano, of Nonnus does not seem intelligible.
Translated from Greece by the Romans, it was Equus, and later on Equus Ales, qualified at times by the adjectives alter, major, Gorgoneus, and Medusaeus; but Isidorus and Lampridius degraded it to Sagmarius Caballus, a Pack-horse;a La Lande cited Ephippiatus, Caparisoned; and elsewhere it was Cornipes, Horn-footed; Sonipes, Noisy-footed; and Sonipes Ales. Germanicus was apparently the first of Latin authors to style it Pegasus.
In the Alfonsine Tables it was Alatus, Winged, Secundus sometimes being added to distinguish it from Equuleus, which preceded it on the sphere; the Almagest of 1551 had Equus Pegasus, which the 17th‑century astronomers extended to Pegasus Equus alatus. Caesius cited Pegasides, and Bayer quoted Equus posterior, volans, aëreus, and dimidiatus, Bellerophon, and Bellerophontes.
Jewish legends made it the mighty Nimrod's Horse; Caesius, one of those of Jeremiah iv, 13, that "are swifter than eagles"; other pious people, the Ass on which Christ made his triumphal entry into Jerusalem; but Julius Schiller exalted it into the Archangel Gabriel. Weigel drew it as the heraldic Lüneburg Horse.
Pegasus appears on coins of Corinth from 500 to 430 B.C., and from 350 to 338 B.C., and 200 years thereafter, on the decadrachma, complete and with wings; as well as on coins of Lampsacus, Scepsis, and Carthage, — on these last with the asterisk of the sun, or with the winged disc, and the hooded snakes over its back. It is also shown on a coin of Narbonne as a sectional winged figure, and as a winged horse on a Euphratean gem, with a bull's head, a crescent moon, and three stars in the field. A coin of Panormus, the modern Palermo, has the Horse's head with what was probably intended for a dorsal plume.
Bochart said that the word is a compound of the Phoenician Pag, or Pega, and Sūs, the Bridled Horse, used for the figurehead on a ship, which would account for the constellation being shown with only the head and fore quarters; but others have considered it of Egyptian origin, from Pag, "to cease," and Sūs, "a vessel," thus symbolizing the cessation of navigation at the change of the Nile flow. From this, Pegasus seems to have been regarded, in those countries at least, as the sky emblem of a ship. In the p324old work the Destruction of Troye, we read of "a ship built by Perseus, and named Pegasus, which was likened to a flying horse."
Brugsch mentions as in its location an Egyptian constellation, the Servant; and some of its stars would seem to be shown on the Denderah planisphere as a Jackal.
The Arabs knew the familiar quadrangle as Al Dalw, the Water-bucket, the Amphora of some Latin imitator, which generally was used for the Urn in Aquarius; and the Arabian astronomers followed Ptolemy in Al Faras al Thānī, the Second Horse, which Bayer turned into Alpheras; Chilmead, into Alfaras Alathem; and La Lande, into Alpharès.
Argelander catalogued 108 stars here, down to the 6th magnitude; and Heis, 178, to the 6 1/2.
The starless region toward Pisces was Al Bīrūnī's Al Baldah, the Fox's Kennel, a term for whose stellar connection I find no explanation.
Before leaving this constellation, it is worth while to note that an asterism, now virtually lost to us and seldom mentioned except in the lists of Al Sufi, Al Amasch, and Kazwini, is described by the last-named under the title Al Faras al Tamm, the Complete Horse. Although somewhat indefinitely marked out, it is said to have occupied the space between the eastern wing of the Swan, the chest of Pegasus, Equuleus, and the tail of Lacerta, drawing for its components from the last three; but Beigel held that it could have existed only with the grammarians, — the Tāmm in its title being easily confused, in transcription, with the Thānī in the Arabians' name for Pegasus. Ideler's Sternnamen is the sole modern work in which I find any reference to this Complete Horse, and even that author, in one passage, seems to regard Monoceros as the modern representative of this somewhat mythical constellation; but this is impossible if Kazwini's description be accepted. Indeed, Ideler himself, later on in his book, changed his opinion to agree with that of Beigel.

α, 2.5, white.
Markab — Flamsteed's Marchab — is the Arabs' word for a Saddle, Ship, or Vehicle, — anything ridden upon, — that was early applied to this star; but they also designated it at Matn al Faras, the Horse's Withers or Shoulder, and Bayer cited Yed Alpheras, the Horse's Hand, or, more properly, Forearm, — the Arabian Yad. Kazwini knew it and β as Al ʽArḳuwah, the Cross-bar of the well in which Al Dalw, the Bucket, was used.
In India it was noted as the junction star of the Bhādra-padā nakshatras, detailed under β. In China it was Shih, a title borrowed from the sieu that it marked.
Brown thinks that, with γ and ζ, it was the Euphratean asterism Lik‑bar‑ra, the Hyaena, — perhaps Ur‑bar‑ra.
Among astrologers it portended danger to life from cuts, or stabs, and fire. It culminates on the 3d of November, and when on the meridian forms, with γ, the southern side of the Great Square, β and δ forming the northern, and all 15° to 18° apart.
Markab's spectrum is Sirian, and it is receding from us at the rate of three quarters of a mile a second.
It is one of the so‑called lunar stars, much observed in navigation.

β, Irregularly variable, 2.2 to 2.7, deep yellow.
This is the Scheat of Tycho, the Palermo Catalogue, and modern lists generally, either from Al Sāʽid, the Upper Part of the Arm, or, as Hyde suggested, from the early Saʽd, appearing in the subsequent three pairs of stars. Bayer had Seat Alpheras; Chilmead, Seat Alfaras; Riccioli, Scheat Alpheraz; and Schickard, Saidol-pharazi.
Arabian astronomers knew it as Mankib al Faras, the Horse's Shoulder, mentioned by Ulug Beg and still occasionally seen as Menkib. Chilmead had Almenkeb.
The Great Square, of which β formed one corner, constituted the double asterism, the 24th and 25th nakshatras, Pūrva, Former, and Uttara, Latter, Bhādra-padā, Beautiful, Auspicious, or Happy Feet, sometimes also called Proshtha-padā, Proshtha meaning a Carp or Ox; but Professor Whitney translated it "Footstool Feet," and said that the authorities do not agree as to the figures by which they are represented, for by some the one, by others the other, is called a Couch or Bed, the alternate one, in either case, being pronounced a Bifaced Figure, or Twins. This Couch is not an inapt representation of the group if both asterisms are taken together, the four stars well marking the feet. Weber calls them Pratishṭhana, a Stand or Support, as Whitney wrote,
an evident allusion to the disposition of the four bright stars which compose it, like the four feet of a stand, table, bedstead, or the like;
the regents of these nakshatras being Augusta Ekapāt, the One-footed Goat, and Ahi Budhya, the Bottom Snake, "two mythical figures, of obscure significance, from the Vedic Pantheon." The 24th manzil, formed by α and β, was Al Fargh al Muḳdim, the Fore Spout, i.e. of the water-bucket, — Al p326Bīrūnī's Al Fargh al Awwal, the First, or the Upper, Spout; and the 24th sieu was these same stars known as Ying She, or Shih, a House, anciently Sal and Shat; but it also comprised parts of Aquarius and Capricornus. They also were the Persian Vaht, the Sogdian and Khorasmian Farshat Bath, and the Coptic Artulos, all signifying something pertaining to Water; while in astrology β indicated danger to mankind from that element.
Within the area of this Square Argelander counted only about 30 naked-eye stars, but in the clearer sky of Athens Schmidt saw 102.
It was in the 24th sieu that the Chinese record a conjunction of the planets Mercury, Mars, Jupiter, and Saturn, on the 28th of February, 2449 B.C., according to Bailly's computations; but we sometimes see this statement made as to five planets, Venus being added, and as having taken place on the 29th of February, that year being bissextile. Smyth indefinitely mentions this conjunction as at some point between α Arietis and the Pleiades; Flammarion states that it was in Capricorn; and Steele alludes to it as of 2246 B.C., and between the tenth and eighteenth degrees of Pisces. At that date the signs and constellations were about coincident.
The variability of β was discovered by Schmidt in 1847, and Argelander found a period of forty-one days; but Schoenfeld thinks that irregular oscillations, in a period of thirty to fifty days, are more probable.
The spectrum of Scheat is of the third type of Secchi's classification, which includes the red and orange stars and most of the variables: "α Orionis, α Herculis, Antares, and ο Ceti (Mira) are good examples."
The star is receding from us about four miles a second.

γ, 3, white,
erroneously placed by Tycho in Pisces, marks the extreme tip of the Horse's wing, so that its name Algenib has been considered as derived from Al Janāḥ, the Wing, but it probably is from Al Janb, the Side. It has sometimes been written Algemo. Al Bīrūnī quoted it, with δ (α Andromedae), as Al Fargh al Thānī, the Second, or Lower, Spout, i.e. of the Bucket. This also is the title of the 25th manzil, but appears in Professor Whitney's list as Al Fargh al Muʼḥir, the Rear Spout, and in Smyth's as Al Fargu.
Chrysococca called it Πήγασος from the constellation.
Reeves said that it is the Chinese Peih, a Wall or Partition, thus taking the title of the 25th sieu, which it marked and, with δ, constituted. It lies at the junction of the nakshatras Bhādrapadā and Revatī; and, with δ, was included in the corresponding lunar station of several other nations.
With the same star and β Cassiopeiae it makes up the Three Guides, all these being almost exactly on the prime meridian, the vernal equinox lying in a starless region of Pisces about 15° south of γ Pegasi. Two 11th‑magnitude stars are close by.

δ, 2.2, white.
This, as already noted, is the same as Alpheratz (α Andromedae), and recognized by astronomers of every age as in either constellation; or, as Aratos wrote, ξυνός ἀστήρ, "a common star." It seems to be unnamed as a member of Pegasus.
Al Achsasi included it with γ in the Fargh al Muʼḥir.
ε, Triple, 2.5, 11.5, and 8.8, yellow, , and blue.
Enif, Enf, and Enir, all titles for this, are from Al Anf, the Nose, by which the Arabians designated it. Scaliger had Enf Alpharas, and Schickard Aniphol Pharasi. It was also Fum al Faras, the Horse's Mouth; and Al Jaḥfalah, the Lip, this last being found on one of their globes.
Bayer quoted from "the interpreters of the Almagest" Grumium and Muscida, respectively Jaw and Muzzle, so describing its position; but these have become proper names for ξ Draconis and π Ursae Majoris. Flamsteed knew it as Os Pegasi.
With θ, and the star α Aquarii, it was the 23d sieu, Goei, or Wei, Steep or Danger, anciently Gui.
Enif's spectrum is Solar, and it is receding from us about five miles a second. Gould thinks it probably variable.

ζ, 3.7, light yellow.
Homam seems to have been first given to this in the Palermo Catalogue, from Saʽd1 al Humām, the Lucky Star of the Hero, in which Ulug Beg included ξ; other lists have Homan. But Hyde said that the original was Al Hammām, Whisperer. Al Tizini mentioned it as Saʽd al p328Naʽamah, the Lucky Star of the Ostriches; and Al Achsasi, as Nāʼir Saʽd al Bahāim, the Bright Fortunate One of the Two Beasts, which Al Sufi had said were θ and ν. Thus ξ was one of the general group Al Suʽūd al Nujūm, the Fortunate Stars.
The Chinese called it Luy Tien, Thunder.
7° to the north of ζ is the point assigned by Denning as the radiant of the first stream of Pegasids, the meteors visible about the 28th of June; although Espin locates it near δ Cygni.

η, Double, 3.2,
on the left forearm, is the Matar of Whitall's Planisphere, from Al Saʽd al Maṭar, the Fortunate Rain; as such, however, ο was included with it.

θ, 3.8, and ν, 4.8,
were Al Sufi's Saʽd al Bahāim, the Good Luck of the Two Beasts; Al Achsasi adding to the group the still brighter ζ. θ alone is Baham in some modern lists; but Ulug Beg had Bihām, the Young of domestic animals.
It appears on the Dresden globe as Al Ḥawāʼim, the Thirsty Camels.
κ, Triple and binary, 4.8. 5.3, and 10.8, yellowish and orange,
marking the right forearm, is unnamed except in China, where it is Jih, the Sun, a title also for κ and λ Librae.
The two largest stars were divided by Burnham in 1880 and found to be 0ʺ.2 apart, this decreasing to 0ʺ.1 in 1891. Their orbital period of revolution is 11 1/2 years, and, with that of δ Equulei, the most rapid known to astronomers until See discovered the binary character of Ll. 9091 in Orion. The first and third stars are 11ʺ apart, at a position angle of 308°.5.

λ, 4.1, and μ, 3.4,
were Saʽd al Bārīʽ, the Good Luck of the Excelling One; but Kazwini designated it as Saʽd al Nāziʽ, the Good Luck of the Camel Striving to Get to Pasture.
p329 ν was Fum al Faras and Al Jaḥfalah, but both titles are more correctly applied to ε.
π was the Chinese Woo, a Pestle.

τ, 4.5,
with υ, was Al Sufi's Saʽd al Naʽamah, which Knobel thinks should be Al Naʽāim, the Cross-bars over a well; but they also were known as Al Karab, the Bucket-rope.
The usual titles for τ — Markab and Sagma or Salma — are from Bayer, but the last two should be Salm, a Leathern Bucket.
λ μ, η ο, and υ τ, forming a group of three pairs, were a noted asterism in Chian, under the title Li Kung.
This long list of names for rather inconspicuous stars shows unusual early interest in the constellation.

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