UGC 12846中的IIP型SN 2007 od：从明亮的最大值到星云阶段的尘埃形成
The Type IIP SN 2007od in UGC 12846: from a bright maximum to dust formation in the nebular phase
摘要：
介绍了IIP型超新星（SN）2007 od的紫外（UV）、光学和近红外（NIR）观测结果，涵盖了从最大光到后期阶段的观测，从而可以详细研究膨胀喷出物中的不同物理现象。这些数据使这个物体成为有史以来研究过的最奇特的IIP之一。SN 2007 od的早期光变曲线类似于明亮的IIPs，具有短暂的平台，明亮的峰值（MV = -18等），但在后期具有非常微弱的光学光变曲线。然而，在放射性衰变过程中加入中红外（MIR）观测，我们估算出M（56 Ni）~ 2 \times 10^-2 M \odot。通过对辐射热光变曲线、喷出物膨胀速度和黑体温度进行建模，我们估计出喷出物的总质量为5 ~ 7.5 M \odot，动能至少为0.5 \times 10^51 erg。早期的光谱揭示了盒状的Hα剖面和巴耳末系的高速特征，这表明喷出物和紧密的星周物质（CSM）之间的相互作用。因此，SN 2007 od可以是IIn型SN和典型IIP型SN之间的中间情况。此外，后期光谱显示出CSM的明确证据，以及喷出物内部形成的尘埃的存在。在星云光谱中观察到的爆炸前短时间的质量损失、明亮的平台、相对少量的56 Ni和微弱的[O I]与超渐近巨星分支（super-AGB）祖先（M~9.7 - 11 M \odot）一致。
英文摘要：
Ultraviolet (UV), optical and near infrared (NIR) observations of the type IIP supernova (SN) 2007od are presented, covering from the maximum light to the late phase, allowing to investigate in detail different physical phenomena in the expanding ejecta. These data turn this object into one of the most peculiar IIP ever studied. The early light curve of SN 2007od is similar to that of a bright IIPs with a short plateau, a bright peak (MV = -18 mag), but a very faint optical light curve at late time. However, with the inclusion of mid infrared (MIR) observations during the radioactive decay we have estimate a M(56Ni) ~ 2\times10^-2 M\odot. Modeling the bolometric light curve, ejecta expansion velocities and black-body temperature, we estimate a total ejected mass was 5 - 7.5 M\odot with a kinetic energy of at least 0.5 \times 10^51 erg. The early spectra reveal a boxy Hα profile and high velocities features of the Balmer series that suggest interaction between the ejecta and a close circum-stellar matter (CSM). SN 2007od may be, therefore, an intermediate case between a Type IIn SN and a typical Type IIP SN. Also late spectra show a clear evidence of CSM and the presence of dust formed inside the ejecta. The episodes of mass loss short before explosion, the bright plateau, along with the relatively small amount of 56Ni and the faint [O I] observed in the nebular spectra are consistent with a super-asympthotic giant branch (super-AGB) progenitor (M~9.7 - 11 M\odot).
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