dimanche 5 octobre 2008

Hercules 10

The Sun flies forward to his brother Sun;
The dark Earth follows wheel'd in her ellipse.

Tennyson's The Golden Year.
Although Johann Tobias Mayer of Göttingen seems to have been the pioneer, in 1760, in the efforts to ascertain the direction of the sun's motion among the stars, yet Sir William Herschel was the first successful investigator as to this, about 1806, and he settled upon the vicinity of λ as the objective point of our solar system, the Apex of the Sun's Way; and his determination was, in a great measure, confirmed by later astronomers.
Some recent observations, however, change this: either to ν of this constellation, to the group of small stars four or five degrees north of west from ν, to the immediate vicinity of Wega in the Lyre, or to the neighborhood of Arided, near the tail of the Swan, — yet all in the same general quarter of the heavens. Thirty-five separate determinations of this Apex, made from 1783 to 1892, locate it variously between 227°18ʹ and 289° of right ascension, and between 14°26ʹ and 53°42ʹ in north declination; the weight of authority being in favor of some point ( Professor Young thinks the Apex in about 267° of right ascension and 31° of declination, but that the data are not yet sufficient to give a very close determination of either the sun's speed or direction, since the problem is embarrassed by the probability of systematic motions among the stars themselves. Results so far obtained are to be regarded only as rather rough approximations. ) in Hercules near the boundary between it and Lyra. The velocity of the sun's motion is found by Potsdam computers of spectroscopic observations to be from 7 1/2 to 11 1/4 miles a second; this is more reliable than the value deduced by other methods.
The Sun's Quit, the point in the heavens opposite to the Apex, according to Todd, lies about midway between the stars Sirius and Canopus.
μ1, a 4th‑magnitude triple, half-way between Wega of the Lyre and α Herculis, was the Chinese Kew Ho, the Nine Rivers.
The distance between the large star and its 9th‑magnitude companion is 31ʺ; while the companion itself is a close binary with a period of about 45 years, the distance seldom exceeding 1ʺ.
ν and ξ, of the 4th magnitude, with the small b, were the Chinese Chung Shan, the Middle Mountain. Some recent investigations place here the Apex of the Sun's Way.
ω, a 4th‑magnitude double, by some early transcriber's error, is now given as Cujam, from Caiam, the accusative of Caia, the word used by Horace for the Club of Hercules, which is marked by this star. Gaiam, Guiam, and Guyam, frequently seen, are erroneous. In Burritt's Atlas the star is wrongly placed within the uplifted right arm.
The Club of Hercules is supposed to have been a separate constellation with Pliny.

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