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arXiv 1109.5873astro-ph.SR
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II-P型超新星膨胀速度的测量

Measuring Expansion Velocities in Type II-P Supernovae

K. Takats, J. Vinko

备注：
19 pages, 10 figures, accepted in MNRAS
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摘要：

我们估计光球速度的II-P型超新星使用SYNOW创建的模型光谱，并与更传统的技术，如互相关，或测量的吸收最小的天鹅座P功能所获得的结果进行比较。基于一个样本的81个观察到的光谱5 SNe，我们表明，SYNOW提供的速度是类似的更复杂的NLTE建模代码获得的，但它们可以在一个计算密集型较少的方式。估算的光球速度（v_model）进行比较，从多普勒频移的吸收最小值的Hbeta和FeII \lambda 5169功能的测量。我们的研究结果证实，FeII速度（v_Fe）有更紧密和更均匀的相关性，估计光球速度比从Hbeta测量的，但都遭受相位相关的系统偏差。与互相关速度的比较也是如此。本文验证并改进了v_Fe、v_H β和v_model之间的关系，为将Ⅱ-P型超新星速度曲线内插/外推到观测未覆盖的相提供了有用的公式。我们还讨论了我们的研究结果的影响的距离测量的类型II-P SNe，并表明，该模型的速度的应用程序是首选的扩大光球方法。

英文摘要：

We estimate photospheric velocities of Type II-P supernovae using model spectra created with SYNOW, and compare the results with those obtained by more conventional techniques, such as cross-correlation, or measuring the absorption minimum of P Cygni features. Based on a sample of 81 observed spectra of 5 SNe, we show that SYNOW provides velocities that are similar to ones obtained by more sophisticated NLTE modeling codes, but they can be derived in a less computation-intensive way. The estimated photospheric velocities (v_model) are compared to ones measured from Doppler-shifts of the absorption minima of the Hbeta and the FeII \lambda5169 features. Our results confirm that the FeII velocities (v_Fe) have tighter and more homogeneous correlation with the estimated photospheric velocities than the ones measured from Hbeta, but both suffer from phase-dependent systematic deviations from those. The same is true for comparison with the cross-correlation velocities. We verify and improve the relations between v_Fe, v_Hbeta and v_model in order to provide useful formulae for interpolating/extrapolating the velocity curves of Type II-P SNe to phases not covered by observations. We also discuss the implications of our results for the distance measurements of Type II-P SNe, and show that the application of the model velocities is preferred in the Expanding Photosphere Method.

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