Probing isotopic ratios at z = 0.89: molecular line absorption in front of the quasar PKS 1830-211

With the Plateau de Bure interferometer, we have measured the C, N, O and S isotopic abundance ratios in the arm of a spiral galaxy with a redshift of 0.89. The galaxy is seen face-on according to HST images. Its bulge intercepts the line of sight to the radio-loud quasar PKS 1830-211, giving rise at mm wavelengths to two Einstein images located each behind a spiral arm. The arms appear in absorption in the lines of several molecules, giving the opportunity to study the chemical composition of a galaxy only a few Gyr old. The isotopic ratios in this spiral galaxy differ markedly from those observed in the Milky Way. The $^{17}$O/$^{18}$O and $^{14}$N/$^{15}$N ratios are low, as one would expect from an object too young to let low mass stars play a major role in the regeneration of the gas.Comment: accepted in A&

Convective Core Mixing: a Metallicity Dependence?

The main scope of this paper is to investigate the possible existence of a metallicity dependence of the overshooting from main sequence stars turbulent cores. We focus on objects with masses in the range ~2.5 Msol - ~25 Msol. Basically, evolutionary time scale ratios are compared with star numbers ratios on the main sequence. Star populations are synthesized using grids of evolutionary tracks computed with various overshooting amounts. Observational material is provided by the large and homogeneous photometric database of OGLE 2 project for the Magellanic clouds. Attention is paid to the study of uncertainties: distance modulus, intergalactic and interstellar reddening, IMF slope and average binarity rate. Rotation and chemical composition gradient are also considered. The result for the overshooting distance is l_over(SMC)= 0.40 +0.12-0.06 Hp (Z=0.004) and l_over(LMC)= 0.10+0.17-0.10 Hp (Z=0.008) suggesting a possible dependence of the extent of the mixed central regions with metallicity within the considered mass range. Unfortunately it is not yet possible to fully disentangle effects of mass and chemical composition.Comment: 13 pages, 8 figures, accepted in Astronomy & Astrophysic

METALLIC ION DEVELOPMENTS AT GANIL

Radioactive ion beams (RIB) are routinely produced at GANIL by fragmentation of the projectile. A possible way to improve the RIB intensity is to increase the primary beam intensity impinging the target. Although high intensities can be obtained with an ECR ion source for gaseous elements, it is more difficult for metallic elements due to the poor ionization efficiency of the source. This report deals with metallic ion beam production at high intensity. Experimental results for Ca, Ni and Fe are presented. The oven and the MIVOC methods are compared

Production de faisceaux d'ions radioactifs par la méthode ISOL pour SPIRAL

CAEN-BU Sciences et STAPS (141182103) / SudocSTRASBOURG-Bib.Central Recherche (674822133) / SudocSudocFranceF

Contribution of different farming and forage systems to biodiversity: an example in a PDO cheese area in French mountains

International audienc

Distributions and fluxes of 226^{226}Ra and 228^{228}Ra in the Irish Sea and in the English channel, in relation to hydrological conditions and sediment interactions

International audienceDistribution of $^{226}$Ra activities and $^{228}$Ra/$^{226}$Ra activity ratios were measured in the surface waters of the Irish Sea and in the English Channel. 226Ra activities vary from 0.001 Bq.l$^{−1}$ for the Atlantic water to 0.002 Bq.l$^{-1}$ for coastal waters, whereas $^{228}$Ra/$^{226}$Ra activity ratios increase from 0.18 to 2.18. The coastal waters are clearly dominated by radium injection from nearshore sediments

Fréquence de l'infection du pigeon par le Pigeon herpèsivurs 1 et le virus de la maladie de Newcastle dans le nord de la France

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