快速膨胀的Ia型SN 2006 X的早期光谱演化
Early Spectral Evolution of the Rapidly Expanding Type Ia SN 2006X
摘要：
We present optical spectroscopic and photometric observations of Type Ia supernova (SN) 2006X from --10 to +91 days after the $B$ -band maximum. This SN exhibits one of the highest expansion velocity ever published for SNe Ia. At premaximum phases, the spectra show strong and broad features of intermediate-mass elements such as Si, S, Ca, and Mg, while the O{ \sc i} $λ$ 7773 line is weak. The extremely high velocities of Si{ \sc ii} and S{ \sc ii} lines and the weak O{ \sc i} line suggest that an intense nucleosynthesis might take place in the outer layers, favoring a delayed detonation model. Interestingly, Si{ \sc ii} $λ$ 5972 feature is quite shallow, resulting in an unusually low depth ratio of Si{ \sc ii} $λ$ 5972 to $λ$ 6355, $\cal R$ (Si{ \sc ii}). The low $\cal R$ (Si{ \sc ii}) is usually interpreted as a high photospheric temperature. However, the weak Si{ \sc iii} $λ$ 4560 line suggests a low temperature, in contradiction to the low $\cal R$ (Si{ \sc ii}). This could imply that the Si{ \sc ii} $λ$ 5972 line might be contaminated by underlying emission. We propose that $\cal R$ (Si{ \sc ii}) may not be a good temperature indicator for rapidly expanding SNe Ia at premaximum phases.
英文摘要：
We present optical spectroscopic and photometric observations of Type Ia supernova (SN) 2006X from --10 to +91 days after the $B$-band maximum. This SN exhibits one of the highest expansion velocity ever published for SNe Ia. At premaximum phases, the spectra show strong and broad features of intermediate-mass elements such as Si, S, Ca, and Mg, while the O{\sc i}$λ$7773 line is weak. The extremely high velocities of Si{\sc ii} and S{\sc ii} lines and the weak O{\sc i} line suggest that an intense nucleosynthesis might take place in the outer layers, favoring a delayed detonation model. Interestingly, Si{\sc ii}$λ$5972 feature is quite shallow, resulting in an unusually low depth ratio of Si{\sc ii}$λ$5972 to $λ$6355, $\cal R$(Si{\sc ii}). The low $\cal R$(Si{\sc ii}) is usually interpreted as a high photospheric temperature. However, the weak Si{\sc iii}$λ$4560 line suggests a low temperature, in contradiction to the low $\cal R$(Si{\sc ii}). This could imply that the Si{\sc ii}$λ$5972 line might be contaminated by underlying emission. We propose that $\cal R$(Si{\sc ii}) may not be a good temperature indicator for rapidly expanding SNe Ia at premaximum phases.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
