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arXiv 1004.1209astro-ph.SRastro-ph.CO
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SN 2007 od:一个具有拱星相互作用的IIP型SN SN

SN 2007od: A Type IIP SN with Circumstellar Interaction

J. E. Andrews, J. S. Gallagher, Geoffrey C. Clayton, B. E. K. Sugerman, J. P. Chatelain, J. Clem, D. L. Welch, M. J. Barlow, B. Ercolano, J. Fabbri, R. Wesson, M. Meixner

摘要:

SN 2007 od展现了IIP型超新星(SN)中罕见的特徴。光学V波段光度测量显示在平台期和星云期之间有一个非常陡峭的亮度下降,大约为4.5等,可能是由于SN 2007 od含有低质量的56 Ni。的光谱显示从正常的IIP型广泛的Halpha发射,到一个复杂的,四个组件的Halpha发射曲线表现出不对称的尘埃消光后,232天的演变。这与SN 1998 S的光谱演化相似,虽然SN 2007 od没有早期窄(~200 km s-1)的H α成分。在这两个SNe中,中等宽度的Halpha发射分量被认为是在喷出物与其星周介质(CSM)之间的相互作用中产生的。SN 2007 od还显示了由于新尘埃而产生的中红外过剩。Halalpha剖面的演化和中红外线过剩的存在提供了强有力的证据,证明SN 2007 od在第232天之前形成了新的尘埃。后期的观测揭示了可见光曲线的平坦化。这种平坦化强烈表明存在光回波,这可能是后期看到的广泛的潜在Halpha分量的主要原因。我们相信多峰的H α发射与喷出物与星周环或环面的相互作用(对于\pm 1500 km s-1的内部组件)以及CSM环平面外的星周物质的单个团块或云(对于-5000 km s-1的外部组件)是一致的。新尘埃最有可能形成的位置是在膨胀的喷出物和它的CSM之间的相互作用所产生的冷的致密壳层中。SN 2007 od尘埃发射的蒙特卡罗辐射转移模型表明,已形成高达4x 10- 4兆太阳的新尘埃。这与其他CCSNe中的尘埃数量相似,如SNe 1999 em、2004 et和2006 jc。

英文摘要:

SN 2007od exhibits characteristics that have rarely been seen in a Type IIP supernova (SN). Optical V band photometry reveals a very steep brightness decline between the plateau and nebular phases of ~4.5 mag, likely due to SN 2007od containing a low mass of 56Ni. The optical spectra show an evolution from normal Type IIP with broad Halpha emission, to a complex, four component Halpha emission profile exhibiting asymmetries caused by dust extinction after day 232. This is similar to the spectral evolution of the Type IIn SN 1998S, although no early-time narrow (~200 km s-1) Halpha component was present in SN 2007od. In both SNe, the intermediate-width Halpha emission components are thought to arise in the interaction between the ejecta and its circumstellar medium (CSM). SN 2007od also shows a mid-IR excess due to new dust. The evolution of the Halpha profile and the presence of the mid-IR excess provide strong evidence that SN 2007od formed new dust before day 232. Late-time observations reveal a flattening of the visible lightcurve. This flattening is a strong indication of the presence of a light echo, which likely accounts for much of the broad, underlying Halpha component seen at late-times. We believe the multi-peaked Halpha emission is consistent with the interaction of the ejecta with a circumstellar ring or torus (for the inner components at \pm1500 km s-1), and a single blob or cloud of circumstellar material out of the plane of the CSM ring (for the outer component at -5000 km s-1). The most probable location for the formation of new dust is in the cool dense shell created by the interaction between the expanding ejecta and its CSM. Monte Carlo radiative transfer modeling of the dust emission from SN 2007od implies that up to 4x 10-4Msun of new dust has formed. This is similar to the amounts of dust formed in other CCSNe such as SNe 1999em, 2004et, and 2006jc.

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