Georges-Antoine-Pons Rayet was a French astronomer and scientist who specialized in spectroscopy, which was a new field for his time. He is noted for discovering Wolf-Rayet stars together with Charles Wolf in 1867.
Background
Georges-Antoine-Pons Rayet was born on December 12, 1839, in Bordeaux, France. Rayet’s family belonged to the Bordeaux upper-middle class. His father, a magistrate removed from office in 1830 because of his Legitimist views, worked in the wine industry in Bordeaux and then, beginning in 1853, in Paris.
Education
When Rayet went to school, his studies did not suffer from this delay: he was admitted to the École Normale Supérieure in 1859 and graduated agrégé in physics three years later.
Career
After teaching for a year at the lycée in Orléans, Rayet obtained a post as a physicist, in the weather forecasting service newly created by Le Verrier, at the Paris observatory.
In addition to his regular work Rayet engaged in astronomical studies, participating in the research of Charles Wolf, an astronomer at the observatory. Their first joint success came in 1865 when they photographed the penumbra of the moon during an eclipse. In the meantime, they had improved spectroscopic techniques and had sought to obtain the spectra of bright comets. A nova appeared on 4 May 1866. Observing it on 20 May, when its brilliance was considerably diminished, Rayet and Wolf detected bright bands in the spectrum, a phenomenon that had never been noticed in star spectra. The bands were the result of a phase that can occur in the evolution of a nova after the explosion and is now known as the Wolf-Rayet stage.
The two astronomers next attempted to determine, through systematic investigation, whether permanently bright stars exhibit the same phenomenon, and in 1867 they discovered three such stars in the constellation Cygnus. “Wolf-Rayet stars,” the spectra of which contain broad, intense emission lines, are rare - barely more than 100 are known. They are very hot stars the mechanism of which has not yet been explained. The expansion of the shell is not sufficient to account for the width of the lines, and there is a great disparity between the energy produced in the interior and the radiated energy.
In 1868 Rayet participated in the mission sent by the Paris observatory to the Malay Peninsula to observe a solar eclipse; he was responsible for spectroscopic work. His observations on the solar prominences provided valuable information, and in conjunction with other observations made during the same eclipse, notably those of J. Janssen, they contributed to the establishment of the first precise data on the sun. Rayet then concentrated on spectroscopic observations of the solar atmosphere and of solar prominences. He identified the brilliant lines of their spectrum with the spectral lines of the elements and developed a theory of the physical constitution of the sun that, at least in its descriptive portion, contains material found in modern theories. This work formed the basis of his doctoral dissertation, which he defended in 1871.
Rayet had no serious disagreement with Le Verrier until the latter entrusted him with running the meteorological service in 1873. Within less than a year Rayet’s opposition to the practical organization of the forecasting of storms - which he had a good reason for judging to be premature - led to his dismissal. Rayet then became a lecturer in physics at the Faculty of Sciences of Marseilles and in 1876 was appointed a professor of astronomy at Bordeaux.
In 1871 the French government proposed to construct several new observatories. Rayet organized a collective survey of the history and equipment of the principal observatories in the world. With collaborators, he wrote three of the five volumes of the study. Rayet took a great interest in the history of science and wrote short, authoritative studies on Greek sundials (1875) and the history of astronomical photography (1887).
Along with his appointment to Bordeaux, Rayet was also designated director of the observatory to be built at Floirac in 1878. He held the post from 1879 and equipped the observatory with the most modern astrometric instruments. Rayet was one of the first supporters of the Carte international photographique du ciel. In 1900 he made an important contribution to the problem of the reduction of photographic plates. Rayet had the satisfaction of being able to publish, a year before his death, the first volume of the Catalogue photographique of the Bordeaux Observatory.
Rayet became a corresponding member of the Académie des Sciences in 1892 and of the Bureau des Longitudes in 1904.
Membership
Rayet became a corresponding member of the Académie des Sciences in 1892.
Personality
Rayet had a sophisticated conception of scientific research and appreciated the advantages of teamwork. He worked thus himself but gave his subordinates great freedom to take initiatives.
Raye was known as a person who was in a possession of great firmness of character. In the last year of his life, despite the poor state of his health, he took part in the expedition to Spain to observe the eclipse of August 1905.
Physical Characteristics:
Rayet died from the effects of a serious lung disease that troubled him during his last years.