THE SUPERSOFT X-RAY PHASE OF NOVA RS OPHIUCHI 2006
THE SUPERSOFT X-RAY PHASE OF NOVA RS OPHIUCHI 2006
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NOVA RS OPHIUCHI 2006 的超软 X 射线相
DOI：
10.1088/0004-637x/727/2/124
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
S. Eyres
中科院分区：
文献类型：
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作者：
J. Osborne;K. Page;A. Beardmore;Goad;M. Bode;Tim O'Brien;S. Starrfield;Thomas Rauch;J. Ness;J. Krautter;G. Schwarz;D. Burrows;N. Gehrels;J. Drake;A. Evans;S. Eyres
对周期性新星蛇夫座RS（RS Oph）2006的2060天超软阶段的快速X射线观测显示了白色矮星（WD）核燃烧的精致细节。首次看到26天后的光学爆发，这一阶段开始与极端的变化可能是由于可变的吸收，虽然内在的WD变化不排除。大约32天后，计数率开始稳步下降。NLTE模式在超软阶段的大气光谱拟合表明，在极端变率阶段，WD的有效温度从1.65 eV增加到1.90 eV，在大约60天后缓慢下降，在80天后更快。从第45天到第60天，测辐射热光度几乎是恒定的，接近爱丁顿，随后的下降可能标志着广泛的核燃烧的结束。在下降之前，软X射线的多重周期性调制存在，并且可能是核聚变驱动的不稳定性的特征。我们的测量是一致的WD质量附近的Wasrasekhar极限，结合推导的积累质量转移从它的二进制同伴，这使我们建议，RS Oph是一个强有力的候选人，未来的超新星爆炸。现在主要的不确定性是WD是否是Ia型超新星所必需的CO类型。这可以通过对爆发的光谱数据进行详细的丰度分析来证实。
Swift X-ray observations of the ∼60 day supersoft phase of the recurrent nova RS Ophiuchi (RS Oph) 2006 show the progress of nuclear burning on the white dwarf (WD) in exquisite detail. First seen 26 days after the optical outburst, this phase started with extreme variability likely due to variable absorption, although intrinsic WD variations are not excluded. About 32 days later, a steady decline in count rate set in. NLTE model atmosphere spectral fits during the supersoft phase show that the effective temperature of the WD increases from ∼65 eV to ∼90 eV during the extreme variability phase, falling slowly after about day 60 and more rapidly after day 80. The bolometric luminosity is seen to be approximately constant and close to Eddington from day 45 up to day 60, the subsequent decline possibly signaling the end of extensive nuclear burning. Before the decline, a multiply-periodic ∼35 s modulation of the soft X-rays was present and may be the signature of a nuclear fusion driven instability. Our measurements are consistent with a WD mass near the Chandrasekhar limit; combined with a deduced accumulation of mass transferred from its binary companion, this leads us to suggest that RS Oph is a strong candidate for a future supernova explosion. The main uncertainty now is whether the WD is the CO type necessary for a Type Ia supernova. This may be confirmed by detailed abundance analyses of spectroscopic data from the outbursts.