Emmanuel Danezis

The stellar temperature scale for stars of spectral types from O8 to F6 and the standard deviation of the MK spectral classification

Empirical effective temperatures of 211 early-type stars found in a previous investigation (Kontizas and Theodossiou, 1980; Theodossiou, 1985) are combined with the effective temperatures of other 313 early-type stars found from literature. From these effective temperatures of a total number of 524 early-type stars of spectral types from O8 to F6 we derive a new stellar temperature scale and the standard deviation of the MK spectral classification.

THE RUSSIAN CALENDARS AFTER THE CHRISTIANIZATION OF THE COUNTRY

The Russians became acquainted with the Christian religion in 860 A.D. In the middle of the 10th Century, Princess Olga of Kiev visited Constantinople and was baptized under the name Elene. Later, when her grandson Vladimir became a Christian, all the Russians became Christians too. Moreover, the Russians adopted the Cyrillic alphabet and the Julian calendar. In 1918 the government replaced the Julian calendar with the Gregorian one. However, the Russian Orthodox Church never accepted the Gregorian or the New Rectified Julian calendar. Even today it retains the old Julian calendar. An important but short-lived change in the history of the Russian calendar took place in the year 1929. Then the seven-day week was abolished being substituted with five-day intervals. This attempt was unsuccessful and finally the Soviet government restored the use of the initial Gregorian calendar and the ancient seven-day week.

Nicephoros Gregoras: the greatest Byzantine astronomer

In the whole of Greece, no eminent astronomers appeared after the great Claudius Ptolemy (second century AD). For ten centuries after Ptolemy we can distinguish only one astronomer: Nicephoros Gregoras (1295–1360). The monk Nicephoros Gregoras is discussed together with his teacher, Theodoros Metochites, one of the most significant scholars of Byzantium. The literary work of Gregoras is especially important, while Byzantine astronomy owes indisputable progress to him. Gregoras was the first to propose, in 1324, a correction to the calculation of the date of Easter, and to the Julian calendar similar to that adopted later, in 1582, by Pope Gregory XIII. This proposition and, more obviously, his dispute with St Gregory Palamas created problems in the relationship between Gregoras and the Church, leading to the desecration of his corpse by a fanatical crowd.

The far UV spectrum of the O4I(n)f star ζ Puppis

A detailed list of line identifications of the far UV spectrum of the O4I(n)f star ζ Puppis (HD 66811) in the wavelength range λλ1168–1984 Å recorded on 16 April, 1981 with the International Ultraviolet Explorer (IUE) is presented. The detailed analysis of the radial velocities measured in the same wavelength range is also presented.