标题： (54Fe+58Ni)/56Ni 比率作为Ia型超新星性质的第二个参数 显示英文标题

标题： The (54Fe+58Ni)/56Ni ratio as a second parameter for Type Ia supernova properties

摘要： （54Fe+58Ni）与56Ni相对含量的变化可能是导致观测到的Ia型超新星（SNe Ia）在其固有亮度和光变曲线形状之间的平均关系上存在分散现象的原因。 我们计算了参数化钱德拉塞卡质量爆炸模型的合成光变曲线，这些模型具有恒定的动能，其中喷发物质被分为内核NSE区域（内部由（54Fe+58Ni）组成，外部由56Ni组成）、中间区域含有中间质量元素以及CO区域。 内核NSE区域的大小和（54Fe+58Ni）与56Ni的比例都系统性地变化。 尽管原始NSE含量相同的模型达到不同的峰值亮度，但它们的光变曲线形状相似。 合成光谱表明，V波段衰减率不受（54Fe+58Ni）/56Ni比例的影响。 虽然56Ni质量和总NSE质量分别是决定峰值亮度和光变曲线形状的主要参数，但（54Fe+58Ni）/56Ni比例的变化（可能取决于前身星的金属丰度）很可能会解释局域SNe Ia在平均亮度-衰减率关系上的部分观测分散。 显示英文摘要

摘要： A variation of the relative content of (54Fe+58Ni) versus 56Ni may be responsible for the observed scatter of Type Ia Supernovae (SNe Ia) about a mean relation between their intrinsic brightness and the shape of their light curve. Synthetic light curves are computed of parametrised Chandrasekhar-mass explosion models of constant kinetic energy, where the ejecta are divided into an inner NSE zone, composed of (54Fe+58Ni) inside and 56Ni outside, an outer zone with Intermediate Mass Elements and a CO zone. Both the size of the NSE zone and the fraction of (54Fe+58Ni) v. 56Ni are varied systematically. Models with the same original NSE content but different (54Fe+58Ni)/56Ni ratios reach different peak brightness but have similar light curve shapes. Synthetic spectra indicate that the V-band decline rate is not affected by the (54Fe+58Ni)/56Ni ratio. While the 56Ni mass and the total NSE mass are the dominant parameters determining the peak luminosity and the shape of the light curve, respectively, a variation in the (54Fe+58Ni)/56Ni ratio, which may depend on the metallicity of the progenitor (Timmes, Brown & Truran 2003) is likely to account for a significant part of the observed scatter of local SNe Ia about the mean brightness--decline rate relation.