Astronomy and Astrophysics – Astronomy
Scientific paper
Jan 1931
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1931natur.127...34.&link_type=abstract
Nature, Volume 127, Issue 3192, pp. 34 (1931).
Astronomy and Astrophysics
Astronomy
Scientific paper
Astronomy in Virgil.Mr. S. B. Gaythorpe appropriately celebrates the Virgil bi-millenary by a paper in the November issue of the Journal of the British Astronomical Association on the astronomical allusions in his poems. He notes that Anchises places astronomy high among the arts that make a nation glorious: With the rod they will trace the paths of heaven and tell the rising of the stars (Aen. VI.). There is a well-known problem as to who was intended by Virgil for the unnamed companion of Conon Who marked out with his rod the whole heavens for man (Eel. III.). Many astronomers names have been suggested, but Mr. Gaythorpe suggests that the allusion is simply to the unknown man who first divided the heavens into constellations. Most authorities have assumed that Virgil was quoting from some work that was ancient even in his days when he spoke (in Georgic I.) of the Bull opening the year with his golden horns. Mr. Gaythorpe notes that there is a sense in which it was true in his own times. In mid-April Aldebaran could have been seen to set heliacally, with the horns of the Bull plainly visible in the twilight, and Sirius (also mentioned in the poem) farther to the left. It is clear that Virgil recognised the practical use of such observations for regulating the times of sowing and other agricultural operations. Mrs. Evershed, in a companion paper, notes that Dante, in the Inferno and Purgatorio makes Virgil give accurate information on many points of astronomy. Virgil seems, however, to have made an error about the southern hemisphere, thinking that its inhabitants reversed not only summer and winter but also night and day When dayspring comes to us, there Hesperus kindles his lamp (Georg. I.). In the corresponding passage in Dante, the travellers have emerged at the antipodes of Italy, so the reversal of night and day comes in correctly there. Spectrum of ? Lyr.A detailed analysis of the spectrum of this extraordinary star was undertaken at intervals by the late Mr. F. E. Baxandall during the last ten years of his life, and the results of his study are now given in the Annals of the Solar Physics Observatory of Cambridge (edited by Prof. F. J. M. Stratton). Two series of spectrograms taken at Cambridge, together with an earlier series kindly lent by the Allegheny Observatory, form the basis of this investigation, which adds many details to our knowledge of this stellar system, without, however, deciding conclusively its physical nature. The absorption spectrum is apparently of dual origin an oscillating B8-type spectrum, and one of type B5, which, though not stationary as previously thought, shows only slight radial velocity variations. There is also a suggestion of a third source of absorption lines which may be of the nature of a Trojan planet. Contrary to earlier hypotheses, the B5 star is apparently smaller and more massive than the B8 star, but is surrounded by an extensive gaseous envelope which is responsible for the bright lines. Several outstanding anomalies still remain unexplained, but the memoir is a valuable contribution to the subject, and forms a fitting memorial to the labours of its originator. Two more Trojan Planets.The Trojan group of minor planets is growing rapidly. Odysseus was discovered some months ago, and two more Trojans are announced in U.A.I. Circ. No. 307. These were discovered at K¶nigstuhl on Oct. 17, and designated UA and UB 1930. Using arcs of six weeks, Drs. Kahrstedt and Stracke have deduced orbits that indicate periods so close to that of Jupiter as to justify the designation of Trojans. The period found for UA is about a year longer than that of Jupiter, but it cannot yet be considered as accurately known. There are now five Trojans (including Odysseus) the longitude of which exceeds that of Jupiter by about 60°, and four (including UA and UB) on the other side of Jupiter. The eccentricity of A is given as 0.29, so that it is nearly twice as far from the sun at aphelion as at perihelion. The magnitudes of both planets are about 14½. The interesting planet 944 Hidalgo, which travels out almost to Saturn's orbit, is now returning sunward, and an ephemeris is given for next July in Kleine Planeten but as the magnitude is only 18½, it will probably not be detected until the following year. Its orbit is quite cometary, but its aspect has always been stellar.
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