标题： Ia型超新星的紫外多样性 显示英文标题

标题： Ultraviolet Diversity of Type Ia Supernovae

摘要： 紫外线（UV）观测类型Ia超新星（SNe Ia）探测爆炸的最外层，SNe Ia的紫外线光谱预计对前身星成分和爆炸细节的差异非常敏感。在这里，我们介绍了第一个高信噪比SN Ia光谱样本，这些光谱延伸到2900 A蓝端。我们重点关注在最大亮度5天内拍摄的光谱。我们的10个SNe Ia样本涵盖了SN Ia光学多样性的主要参数空间。我们发现，SNe Ia在紫外线中的多样性显著大于光学中，光谱方差随着波长减小而继续增加，至少到1800 A（我们数据的极限）。大多数紫外线方差与光学光曲线形状相关，而光谱形状与抛射物速度或宿主星系形态之间没有明显且唯一的相关性。使用光曲线形状作为主要变量，我们创建了峰值亮度时SNe Ia的紫外线光谱模型。通过该模型，我们可以检查个别SNe相对于仅基于其光曲线形状的预期如何变化。这样做，我们确认了SN 2011fe在短波长处的通量过剩，这与其前身星具有亚太阳金属度一致。虽然其他大多数SNe Ia没有显示出与模型的大偏差，但ASASSN-14lp在短波长处有通量不足，表明其前身星相对金属丰富。 显示英文摘要

摘要： Ultraviolet (UV) observations of Type Ia supernovae (SNe Ia) probe the outermost layers of the explosion, and UV spectra of SNe Ia are expected to be extremely sensitive to differences in progenitor composition and the details of the explosion. Here we present the first study of a sample of high signal-to-noise ratio SN Ia spectra that extend blueward of 2900 A. We focus on spectra taken within 5 days of maximum brightness. Our sample of ten SNe Ia spans the majority of the parameter space of SN Ia optical diversity. We find that SNe Ia have significantly more diversity in the UV than in the optical, with the spectral variance continuing to increase with decreasing wavelengths until at least 1800 A (the limit of our data). The majority of the UV variance correlates with optical light-curve shape, while there are no obvious and unique correlations between spectral shape and either ejecta velocity or host-galaxy morphology. Using light-curve shape as the primary variable, we create a UV spectral model for SNe Ia at peak brightness. With the model, we can examine how individual SNe vary relative to expectations based on only their light-curve shape. Doing this, we confirm an excess of flux for SN 2011fe at short wavelengths, consistent with its progenitor having a subsolar metallicity. While most other SNe Ia do not show large deviations from the model, ASASSN-14lp has a deficit of flux at short wavelengths, suggesting that its progenitor was relatively metal rich.