We performed an analysis of the main theoretical uncertainties that affect the radius of low- and very-low mass-stars predicted by current stellar models. We focused on stars in the mass range 0.1-1Msun, on both the zero-age main-sequence (ZAMS) and on 1, 2 and 5 Gyr isochrones. First, we quantified the impact on the radius of the uncertainty of several quantities, namely the equation of state, radiative opacity, atmospheric models, convection efficiency and initial chemical composition. Then, we computed the cumulative radius error stripe obtained by adding the radius variation due to all the analysed quantities. As a general trend, the radius uncertainty increases with the stellar mass. For ZAMS structures the cumulative error stripe of very-low mass stars is about $\pm 2$ and $\pm 3$ percent, while at larger masses it increases up to $\pm 4$ and $\pm 5$ percent. The radius uncertainty gets larger and age dependent if isochrones are considered, reaching for $M\sim 1$Msun about $+12(-15)$ percent at an age of 5 Gyr. We also investigated the radius uncertainty at a fixed luminosity. In this case, the cumulative error stripe is the same for both ZAMS and isochrone models and it ranges from about $\pm 4$ percent to $+7$ and $+9$($-5$) percent. We also showed that the sole uncertainty on the chemical composition plays an important role in determining the radius error stripe, producing a radius variation that ranges between about $\pm 1$ and $\pm 2$ percent on ZAMS models with fixed mass and about $\pm 3$ and $\pm 5$ percent at a fixed luminosity.
Uncertainties in modeling low-energy neutrino induced reactions on iron group nuclei
利用基于相对论和Skyrme能量密度泛函以及壳模型的框架，计算和比较了54，56 Fe和58，60 Ni的带电中微子-核截面.根据预测的Gamow-Teller跃迁强度和现有数据、截面的多极分解以及Michel通量和Fermi-Dirac分布的平均截面，对当前中微子-核截面模型的理论不确定性进行了评估。采用不同的微观方法和模型，我们估算了DAR中微子-56 Fe的截面及其理论不确定度：<sigma>_th=（258+-57）10^{-42} cm ^2，与实验值：<sigma>_exp=（256+-108+-43）10^{-42} cm ^2非常吻合。
