The disagreement between theory and observations for surface 7Li abundance is a long standing problem which requires a quantitative analysis of the main uncertainties affecting theoretical models. We performed a detailed evaluation of the errors affecting 7Li abundance predictions coming from the chemical composition and the adopted physical inputs. Then, present 7Li abundances have been compared with the observations available for five young open clusters of different ages and chemical composition, namely, Ic 2602, α Per, Blanco1, Pleiades, and Ngc 2516, and for four detached double-lined eclipsing binary systems. We confirm, for standard models, the disagreement between theoretical predictions and 7Li observations for young open clusters if the same convection efficiency (mixing length parameter) during the pre-main sequence and the main sequence phase is adopted. However, if during the pre-main sequence a convection efficiency lower than the main sequence one is used, a satisfactory agreement with 7Li observations can be achieved. Such value is with a good approximation independent of the age and the metallicity, at least in the range covered by our analysis.
7Li abundance in pre-main sequence stars. Testing theory against clusters and binary systems
TOGNELLI, EMANUELE;DEGL'INNOCENTI, SCILLA;PRADA MORONI, PIER GIORGIO
2012-01-01
Abstract
The disagreement between theory and observations for surface 7Li abundance is a long standing problem which requires a quantitative analysis of the main uncertainties affecting theoretical models. We performed a detailed evaluation of the errors affecting 7Li abundance predictions coming from the chemical composition and the adopted physical inputs. Then, present 7Li abundances have been compared with the observations available for five young open clusters of different ages and chemical composition, namely, Ic 2602, α Per, Blanco1, Pleiades, and Ngc 2516, and for four detached double-lined eclipsing binary systems. We confirm, for standard models, the disagreement between theoretical predictions and 7Li observations for young open clusters if the same convection efficiency (mixing length parameter) during the pre-main sequence and the main sequence phase is adopted. However, if during the pre-main sequence a convection efficiency lower than the main sequence one is used, a satisfactory agreement with 7Li observations can be achieved. Such value is with a good approximation independent of the age and the metallicity, at least in the range covered by our analysis.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
