To be published in slightly modified form in The Biographical Encyclopedia of Astronomers, 2d edition September 11, 2018 Biography of eight astronomers and physicists Emmanuel Davoust1 IRAP, Universit´ede Toulouse, CNRS, 14 Avenue Edouard Belin, F-31400 Toulouse, France e-mail: [email protected] Received 2012; accepted ABSTRACT We provide a brief biography of seven French astronomers and physicists and of a Russian astronomer from the 19th and 20th centuries. Roger Bouigue (1920- ) was the director of Toulouse Observatory in the 1960s. Claude-Louis Mathieu (1783-1875), a member of Bureau des Longitudes, worked in geodetics and celestial mechanics. Claude Pouillet (1790- 1868), a physics professor, was the first to measure the solar constant. Yves Rocard (1903-1992) conducted research in many fields of physics, and founded the radioastronomy Observatory of Nan¸cay. Jean R¨osch (1915-1999) was the director of Pic du Midi Observatory for over thirty years, and in this capacity lead it to the forefront of research in high-resolution solar and planetary astronomy. Cyrille Souillart (1828-1898) had a lifelong interest in the theory of Jupiter's satellites. Jules Violle (1841- 1923) was a physics professor who determined the temperature of the solar photosphere. The Russian astronomer Kirill Ogorodnikov (1900-1985) wrote a well-known manual on stellar dynamics. Key words. Biography, astronomer, physicist 1. Roger BOUIGUE of Science of Paris University in 1953, with Andr´eDanjon and the future Nobel Prize winner Alfred Kastler on the Roger Bouigue was the director of Toulouse Observatory jury. and a professor of astronomy at the Faculty of Science of Bouigue was a talented lecturer, teaching astrophysics Toulouse. He developed the study of carbon stars and spec- at Toulouse University starting in 1953, and he became one troscopic binaries at Toulouse Observatory. He identified of the few full professors at the Faculty of Science in 1962. the relatively rare carbon stars with unusually strong iso- topic bands of carbon as a homogeneous group and called Bouigue became the director of Toulouse Observatory them J-type carbon stars. in 1961, and, after finishing the astrometric reductions linked to the fourth catalogue of the Toulouse zone of the Roger Bouigue was born in Toulouse (France) on Carte du Ciel, organized research around the observation August 1, 1920. He was the son of the head of a workshop of spectroscopic binary stars. However, since most direc- of \Ponts et Chauss´ees",the French Highways Agency. He tors of French observatories were former students of Ecole was too young by a few months to be conscripted into the Normale Sup´erieure,he felt that he was at a disadvantage French army during WWII and served instead for eight running the Institute and interacting with astronomers at months on \Chantiers de Jeunesse en France" after the other institutes. In 1964 he participated in the search in armistice. He was a primary school teacher in the Pyrenees South Africa for a site for the future European Southern from 1940 to 1945, and obtained a Bachelor of Science de- Observatory. Jean R¨osch succeeded him as director in 1971. gree from Toulouse University in 1945. He taught at a high- school in the Pyrenees for two years before joining Toulouse In 1974 Bouigue became a scientific consultant for the Observatory in 1947, replacing Pierre Lacroute who had French military laboratories and developed a theory of left for Strasbourg. He pursued his predecessor's research molecular collisions which enabled these laboratories to projects { the spectroscopic study of binary and carbon solve a problem linked to the ignition and combustion of stars, using the observatory's instruments and, occasion- small- and medium-size ordinance. ally, the 1.2meter telescope at Haute-Provence Observatory, After his retirement in 1987, Bouigue worked for twenty where he obtained the spectra of carbon stars for his thesis. years at the library of a local learned society and wrote arXiv:1208.4739v1 [physics.hist-ph] 23 Aug 2012 He also briefly conducted theoretical studies in molecular a book entitled \Positions and Motions of the Stars: physics to determine the vibrational temperatures of the Introduction to Astronomy with your PC, with programs CN molecule and of the Swan bands of C2. He is mostly ac- in Basic on floppy disc". knowledged for having identified the common spectral fea- Bouigue was awarded the bronze medal of the CNRS tures of a small category of carbon stars, those with unusual (the French National Research Council) in 1955, was named isotopic abundances of carbon, and grouped them into a Chevalier (knight) of the Ordre des Palmes Acad´emiquesin single class, which he called J stars. 1957 and Officer in 1980. He received the Pierre Guzman Bouigue defended a thesis on two subjects, prize of the French Academy of Science in 1965 for his re- \Contribution to the study of red carbon stars" and search in stellar spectrography. He also became correspond- \A new machine for measuring spectra", at the Faculty ing member of the Royal Academy of Science of Belgium 1 Emmanuel Davoust: Biography of eight astronomers and physicists des Longitudes during the absence of its incumbent. The latter, Fran¸cois Arago, went with Jean-Baptiste Biot to the Balearic Islands to extend the measurement of the French meridian. Mathieu participated in the routine meridian observations of stars. Upon Arago's return in 1809, Mathieu obtained a position of astronome-adjoint at Paris Observatory in 1809, where he shared a lodging with Alexander von Humboldt. He reduced the geodetic observa- tions together with Biot and Johann Karl Burkhardt. Two mutually compensating errors were later found in the reduc- tion, and Mathieu participated in its reanalysis in 1841 with two other members of the Bureau des Longitudes, Charles- Louis Largeteau and Pierre Daussy. Another geodetic campain in which he participated with Arago was the measurement of the difference in longitude between Paris and Greenwich in 1821-23. The measure- ments on the French side were never given to the British who had to rely on the published coordinates of Calais to derive the longitude difference of 9m 21.18s. A more accu- rate value of 9m 20.63s was obtained in 1854. In 1812-13 Mathieu and Arago observed the star 61 Cygni to determine its parallax. Instead of measuring its position with respect to nearby stars, they determined the annual variations of the zenith angle of the star at the meridian. But such a method was bound to fail for par- Fig. 1. Roger BOUIGUE in 1987 allaxes smaller than half a second of arc because of at- mospheric refraction and other sources of errors. They re- peated the measurements in 1823 and correctly concluded in 1968 and member of the New York Academy of Sciences that the parallax of the star was less than half a second. In in 1982. 1838 Bessel used the classical method to derive a parallax of 0.31, which astounded astronomers at the time at the Selected references large distance of the star. In 1819 he participated in the observations of a comet, Bouigue, R. (1954). \Contribution `al'´etudedes ´etoilesrouges car- and in 1835 of Halley's comet, from which Arago concluded bon´eesII." Annales d'Astrophysique 17: 104-151. Bouigue, R. (1960). \Notice sur les titres et travaux scientifiques de that the luminosity of comets comes from reflected sunlight. M. Roger Bouigue." Archives of Observatoire Midi-Pyr´en´ees. At the request of Arago, who was then a member of Lombard, J.M., Bouigue, R. (1984). \Application of molecular colli- the commission of lighthouses, Mathieu participated with sions theory to gas-solid reactions : ignition and combustion of py- rotechnic compositions." 9th International Pyrotechnics Seminar, Augustin Fresnel in experiments to improve lighthouses in p.851-860. 1819. Fresnel's invention in 1820 of the lens that bears his name definitively settled the matter, to the great satisfac- tion of sailors. 2. Claude-Louis MATHIEU In 1822 the Bureau des Longitudes decided to re- Claude-Louis Mathieu, who was three years older than measure the speed of sound, considering that the value Fran¸coisArago, was admitted to Ecole Polytechnique the obtained in 1738 was of poor accuracy. Mathieu partici- same year as Arago, and spent most of his career following pated in the new measurements but the resulting value of in the footsteps of his friend and colleague, assisting him in 331.2m/s (at 0 degree centigrade) was a only slight im- various scientific endeavors. He became an active member provement. of the scientific establishment, of the French Academy of After the death of Delambre in 1822, leaving an unfin- Science, teaching at various schools, and played a signifi- ished History of Astronomy, Mathieu proceeded to write cant role in French politics as a member of parliament. the missing parts, mainly about the 18th century, and the Claude-Louis Mathieu was born in M^acon(France) on work was published in 1827. When Arago's complete works November 25, 1783. His father was a carpenter, and could were published by his sons a year after his death, a quar- not afford to pay for his education. His early gift for math- rel arose between them and Mathieu about the title of the ematics were noticed by a priest in his home town, who works, and it created an enduring rift between them which taught him algebra and arithmetics. In 1801, he went to resurfaced at the publication of Arago's Popular Astronomy Paris with a letter of introduction to Joseph Delambre, who in 1868. took him under his protection and housed him in his obser- In 1851 he made observations of scintillation from stars vatory.