The European Astronomical Society EAS has awarded the 2013 prizes to two female researchers from the Observatoire de Paris. Elisabetta Caffau got the best early career prize for observation in astrophysics. Suzy Collin-Zahn received the Lodewijk Woltjer lecture prize which honours astronomers of outstanding scientific distinction.
Best early career researcher
in astrophysics observation
In 2009, Elisabetta Caffau obtained a PhD in observational astronomy from the Observatoire de Paris. She then worked there in a one year post-doctoral position. In 2011, she discovered the most primitive star currently known SDSS J1029+1729 and determined its chemical composition. This is considered as an important step toward better understanding of stars formation and chemical elements in the early history of the Milky Way.
Elisabetta Caffau has developed a method to obtain high precision elements abundances from 3D hydrodynamical computations. She applied this to recognize extremely metal poor stars in the crowd of low-resolution spectra provided by large spectroscopic surveys like Sloan Digital Sky Survey. Thanks to this very efficient tool, she discovered in 2011 the most primitive star currently known SDSS J1029+1729 and defined its chemical composition. The discovery of a star with an extremely low abundance of all the elements from carbon to zinc is considered as a key for our understanding of the formation of stars and chemical elements in the early history of the Milky Way.
Work was carried out at Galaxie Etoiles Physique et Instrumentation GEPI department of Observatoire de Paris, centre for astronomy of Heidelberg University, and Landessternwarte Königstuhl.
After several years of work as professor in secondary schools in Italy, Elisabetta Caffau obtained a PhD in observational astronomy from Observatoire de Paris in 2009. She then stayed there in a one year post-doctoral position. She obtained a three year grant at the Zentrum für Astronomie of the Heidelberg University. With an infrared spectrograph of the ESO VLT telescope, she measured phosphorus abundance of twenty cool stars in the Galactic disk for the first time.
Lodewijk Woltjer medal and lecture
Suzy Collin-Zahn, astronome honoraire at the Observatoire de Paris, has made fundamental contributions to our understanding of Active Galactic Nuclei AGNs. These are among the most luminous objects in the Universe. Their emission covers the electro-magnetic spectrum from radio waves to gamma rays. Suzy Collin has been active in research, teaching and popularisation of astronomy.
Suzy Collin-Zahn turned to the study of Active Galactic Nuclei AGNs in the early days of the subject after the discovery of quasars in the 1960s. She subsequently led during many years a dynamic research group at the Observatoire de Paris. In particular, she was the first to show that a central source is responsible for exciting emitted radiation, which should vary quickly. More recently, monitoring of this has allowed researchers to study the nuclei structure of these objects and to determine the central black hole mass. She turned then to the study of the « accretion disc » where gas is spiralling towards black hole, thus producing radiation. Among other accomplishments, she showed that in certain AGNs where the luminosity reaches maximum allowed value, the black hole must be accreting at a rate exceeding that suggested by luminosity (the super Eddington value). Furthermore, she showed that when luminosity is very weak, stars can form in the outer gravitationnally unstable regions of the disc. This could explain the presence of many young stars close to the supermassive black hole in some currently inactive galaxies, as well as those located near the center of the Milky Way : they presumably formed during an outburst of activity a few million years ago.
Suzy Collin has made valuable contribution to astrophysics through research, teaching and popularisation. Now retired, she remains an "astronome honoraire" (honorary astronomer) in the Laboratoire Univers et Théorie LUTH at Observatoire de Paris.
