The Natural History of ‘Oumuamua

International audienceThe discovery of the first interstellar object passing through the Solar System, 1I/2017 U1 (`Oumuamua), provoked intense and continuing interest from the scientific community and the general public. The faintness of `Oumuamua, together with the limited time window within which observations were possible, constrained the information available on its dynamics and physical state. Here we review our knowledge and find that in all cases, the observations are consistent with a purely natural origin for `Oumuamua. We discuss how the observed characteristics of `Oumuamua are explained by our extensive knowledge of natural minor bodies in our Solar System and our current knowledge of the evolution of planetary systems. We highlight several areas requiring further investigation

The use of definitive methods based on radiochemical neutron activation analysis for the determination of selenium and arsenic in materials used in proficiency testing

This article describes the use of two definitive methods for the determination of Se and As traces in biological materials intended for proficiency testing. Radiochemical neutron activation analysis (RNAA) definitive methods are based on reactor neutron activation with a very selective and quantitative post-irradiation separation of the indicator radionuclide by column chromatography, followed by γ-ray spectrometric measurement. Each of these methods has detection limit of the order of ng·g–1 or better, and yields accurate results. The expanded standard uncertainty for both methods is ca. 4%. Definitive RNAA methods were used for establishing assigned values for Se and As in materials employed in proficiency testing of “Plants” series