月球掩星的多光谱观测：I。解决AFGL 5440周围的尘壳
Multi-spectral Observations of Lunar Occultations: I. Resolving The Dust Shell Around AFGL 5440
摘要：
我们目前的观测和建模的尘埃笼罩的碳星AFGL 5440的月球掩星。观测是在1 - 4微米的连续波长范围内进行的，使用的是专门为此目的设计的高速分光光度计。我们发现，掩星条纹不能用任何单一尺寸的模型来拟合。我们使用DUSTY辐射转移代码来模拟拱壳，并拟合观测到的掩星光变曲线和文献中描述的光谱能量分布。我们发现一个强有力的约束尘埃壳的内半径，Tmax = 950 K +/-50 K，和光学深度在5微米的0.5 +/- 0.1。观测结果与密度梯度为r^-2的模型或由伊韦齐克和埃利楚尔推导出的辐射驱动的流体动力外流的密度梯度模型拟合得最好。我们的模型不能拟合观测到的IRAS 60微米通量，而不假设大量的石墨或假设一个显着较高的质量损失率在过去。
英文摘要：
We present observations and modeling of a lunar occultation of the dust-enshrouded carbon star AFGL 5440. The observations were made over a continuous range of wavelengths from 1 - 4um with a high-speed spectrophotometer designed expressly for this purpose. We find that the occultation fringes cannot be fit by any single-size model. We use the DUSTY radiative transfer code to model a circumstellar shell and fit both the observed occultation light curves and the spectral energy distribution described in the literature. We find a strong constraint on the inner radius of the dust shell, Tmax = 950 K +/- 50K, and optical depth at 5um of 0.5 +/- 0.1. The observations are best fit by models with a density gradient of r^-2 or the gradient derived by Ivezic & Elitzur for a radiatively driven hydrodynamic outflow. Our models cannot fit the observed IRAS 60um flux without assuming a substantial abundance of graphite or by assuming a substantially higher mass-loss rate in the past.
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