37 research outputs found
The MACHO Project Large Magellanic Cloud Variable Star Inventory. VIII. The Recent Star Formation History of the LMC from the Cepheid Period Distribution
We present an analysis of the period distribution of Cepheids in the Large Magellanic Cloud, based on data obtained by the MACHO microlensing experiment and on a previous catalogue by Payne-Gaposchkin. Using stellar evolution and pulsation models, we construct theoretical period-frequency distributions that are compared to the observations. These models reveal that a significant burst of star formation has occurred recently in the LMC ( years). We also show that during the last years, the main center of star formation has been propagating from SE to NW along the bar. We find that the evolutionary masses of Cepheids are still smaller than pulsation masses by % and that the red edge of the Cepheid instability strip could be slightly bluer than indicated by theory. There are Cepheids with periods below days cannot be explained by evolution theory. We suggest that they are anomalous Cepheids; a number of these stars are double-mode Cepheids
Yersinia enterocolitica biotype 1B case report: an unusual pathogen in an osteoarticular infection on device
International audienceYersinia enterocolitica is an aero-anaerobic Gram-negative coccobacilli of the Enterobacteriaceae family, rarely reported in osteoarticular infection