mercredi 1 octobre 2008

Sagitta 5

There is in front another Arrow cast
Without a bow; and by it flies the Bird
Nearer the north.

Brown's Aratos.
Sagitta, the Arrow, the French Flèche, the German Pfeil, and the Italian Saetta, lies in the Milky Way, directly north of Aquila and south of Cygnus, pointing eastward; and, although ancient, is insignificant, for it has no star larger than the 4th magnitude, and none that is named.
It has occasionally been drawn as held in the Eagle's talons, for the bird was armor-bearer to Jove; but Eratosthenes described it separately, as Aratos had done, and as it now is on our maps. The common belief that the latter included it with his Αἰετός was based, Grotius said, on an error in the version of Germanicus. And it has been regarded as the traditional weapon that slew the eagle of Jove, or the one shot by Hercules towards the adjacent Stymphalian birds, and still lying between them, whence the title Herculea; but Eratosthenes claimed it as the arrow with which Apollo exterminated the Cyclopes; and it sometimes was the Arrow of Cupid. The Hyginus of 1488 showed it overlying a bow; indeed, Eratosthenes called it Τόξον, a Bow, signifying Arrows in its plural form; Aratos mentioned it as the Feathered Arrow and the Well-shaped Dart, the ἄλλος ὀϊστός of our motto, "another arrow," in distinction from that of Sagittarius. Still, it has often been thought of as the latter's weapon strayed from its owner. Hipparchos and Ptolemy had plain Ὀϊστός.
Latin authors of classical times and since knew it as Canna, Calamus, and Harundo, all signifying the Reed from which the arrow-shafts were formed; and as Missile, Jaculum, and Telum, the Weapon, Javelin, and Dart; Telum descending even to Kepler's day. But Sagitta was its common title with all the Romans who mentioned its stars; Cicero characterizing it as clara and fulgens, which, however, it is not.
Bayer, who ascribed to it the astrological nature of Mars and Venus, picked up several strange names: Daemon, Feluco, and Fossorium, apparently unintelligible here; Obelus, one of the σεμεῖαι, or notae, of ancient grammarians, or, possibly, an Obelisk, which it may resemble;a Orfercalim, cited by Riccioli and Beigel from Albumasar for the Turkish Otysys Kalem, a Smooth Arrow; Temo meridianus, the Southern Beam; Vectis, a Pole; Virga and Virgula jacens, a Falling Wand. The Missore attributed to Cicero is erroneous, and was never used by the latter as a star-name, but for the one who shot the arrow; while the Musator of Aben Ezra is either a barbarism for Missore, or may be for the Arabic Saṭar, a Straight Line.
The Hebrews called it Ḥēṣ or Ḥēts; the Armenians and Persians, Tigris; and the Arabians, Al Sahm, all meaning an Arrow; this last, given on the Dresden globe, being turned by Chilmead into Alsoham, by Riccioli into Schaham, and by Piazzi into Sham.
In some of the Alfonsine Tables appeared Istusc, repeated in the Almagest of 1515 as Istiusc, both probably disfigured forms of ὀϊστός; and the Alfonsine Tables of 1521 had Alahance, perhaps from the Arabic Al Ḣams or Ḣamsah, the Five (Stars), its noticeable feature. The same Almagest also had Albanere, adding est nun, all unintelligible except from Scaliger's note:
legendum Alhance, id est Sagitta, hebraicae originis, converso Dages in Nun, ut saepe accidit in Arabismo et Syriasmo.
Schickard wrote it Alchanzato.
Sagitta is not noticed in the Reeves list of Chinese asterisms.
Caesius imagined it the Arrow shot by Joash at Elisha's command, or one of those sent by Jonathan towards David at the stone Ezel; and Julius Schiller, the Spear, or the Nail, of the Crucifixion.
Originally only 4° in length, modern astronomy has stretched the constellation to more than 10°; Argelander assigning to it 16 naked-eye stars, and Heis 18. Eratosthenes gave it only 4.
It comes to the meridian on the 1st of September.
None of Sagitta's stars seem to have been named, but its triple ζ is an interesting system. It has long been known as double, but the larger star was discovered by the late Alvan G. Clark to be itself an extremely close double and rapid binary.
The components are of 6, 6, and 9 magnitudes; the two larger 0ʺ.1 apart in 1891, at a position angle of 182°.8. The smallest star is 8ʺ.5 distant. The colors are greenish, white, and blue.

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