标题： IRC +10 216周围壳层的新奇CO数据 显示英文标题

标题： New peculiar CO data of the shell around IRC +10 216

摘要： 1996年6月使用IRAM 30米望远镜拍摄的著名碳星IRC+10216的CO(1-0)源谱显示，在红翼基线轮廓的-18.3至-14.3公里/秒范围内存在过量发射。 这种过量发射在1997年1月得到确认，但在1997年4月和1998年6月的IRAM光谱中缺失。 在此恒星或任何其他AGB恒星中以前从未观察到这种瞬态特征。 1997年4月，我们对该恒星的星周壳层进行了110"范围内的测绘。 J=1-0和J=2-1谱线都显示出“尖峰”或成分，这些成分随着包层位置的变化而变化。 其中一个成分对应于上述提到的速度间隔。 一个直接的结论是，星周壳层并非球对称，这与基于较低光谱分辨率数据所认为的情况相反。 我们可能正在观测一个复杂几何结构的发射。 既不是盘状结构也不是双风结构似乎能解释观测结果。 红翼过量发射的瞬态行为可以通过一个大（约5×10^{13} 厘米）的团块来合理解释，该团块由于内部运动而膨胀。 显示英文摘要

摘要： A CO(1-0) on-source spectrum of the well-known carbon star IRC+10216 taken with the IRAM 30m telescope in June 1996 shows excess emission between -18.3 and -14.3 km/s at the red wing of the underlying profile. The excess emission is confirmed in January 1997 but is absent in April 1997 and June 1998 IRAM spectra. Such a transient feature has not been seen before in this star or any other AGB star. In April 1997 we mapped the circumstellar shell out to 110". Both the J = 1-0 and J = 2-1 spectra show ``spikes'' or components which vary in strength with position in the envelope. One of these components corresponds to the velocity interval mentioned above. An immediate conclusion is that the circumstellar shell is not spherically symmetric, contrary to what was believed based on lower spectral resolution data. We are probably seeing emission from a complex geometrical structure. Neither a disk structure nor a double-wind structure seem to be able to explain the observations. The on-source transient behaviour of the red excess emission can reasonably well be explained by a single large (about 5 x 10^{13} cm) blob, that expands due to internal motion.