DQ类武仙座新星的偏振和光谱学：V5668人马座（2015）
Polarimetry and Spectroscopy of the `Oxygen Flaring' DQ Herculis-like nova: V5668 Sagittarii (2015)
摘要：
经典新星是双星系统中白矮星表面的爆发。从白矮星表面喷射出的物质通常会在系统周围形成一个由气体和尘埃组成的轴对称壳层。当在天空的平面上观察时，这些贝壳的三维结构很难解开。在这项工作中，开发了一个几何模型来解释2015年人马座V5668新星的新观测结果。根据新星壳层形态学来理解电离结构，并估计直接跟随光变曲线的尘埃下沉的发射分布。高节奏的光学偏振和光谱观测的新星。喷出物的形态运动学和光电离结构的建模。初步观测结果，包括宽带偏振和光谱的V5668 Sgr新星爆发期间。这些观测结果的变化为新星壳的演化结构提供了线索。壳层的位置角由旋光测量法推导出，这归因于小尘埃颗粒的散射。在新星外流的冲击建议在测光和这些新星壳的效果说明了各种物理诊断。密度和温度的变化作为超软源阶段的新星开始进行了讨论。气体密度被认为是10 $^{9}$厘米$^{-3}$的新星在其极光阶段的顺序。在超软源开启的时刻，中心恒星系统的黑体温度估计在$2.2\times10^{5}$ K附近，发现通常称为“氮耀斑”的4640 $\rmÅ$附近的混合物更自然地解释为4638 - 4696 $\rmÅ$的O~{ \sc ii}多重态（V1）的耀斑，即“氧耀斑”。
英文摘要：
Classical novae are eruptions on the surface of a white dwarf in a binary system. The material ejected from the white dwarf surface generally forms an axisymmetric shell of gas and dust around the system. The three-dimensional structure of these shells is difficult to untangle when viewed on the plane of the sky. In this work a geometrical model is developed to explain new observations of the 2015 nova V5668 Sagittarii. To understand the ionisation structure in terms of the nova shell morphology and estimate the emission distribution directly following the light-curve's dust-dip. High-cadence optical polarimetry and spectroscopy observations of a nova are presented. The ejecta is modelled in terms of morpho-kinematics and photoionisation structure. Initially observational results are presented, including broadband polarimetry and spectroscopy of V5668 Sgr nova during eruption. Variability over these observations provides clues towards the evolving structure of the nova shell. The position angle of the shell is derived from polarimetry, which is attributed to scattering from small dust grains. Shocks in the nova outflow are suggested in the photometry and the effect of these on the nova shell are illustrated with various physical diagnostics. Changes in density and temperature as the super soft source phase of the nova began are discussed. Gas densities are found to be of the order of 10$^{9}$ cm$^{-3}$ for the nova in its auroral phase. The blackbody temperature of the central stellar system is estimated to be around $2.2\times10^{5}$ K at times coincident with the super soft source turn-on. It was found that the blend around 4640 $\rmÅ$ commonly called `nitrogen flaring' is more naturally explained as flaring of the O~{\sc ii} multiplet (V1) from 4638 - 4696 $\rmÅ$, i.e. `oxygen flaring'.
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