来自斯皮策远红外观测的M31的尘埃校正表面测光
Dust-corrected surface photometry of M 31 from the Spitzer far infrared observations
摘要：
我们创建了一个模型，用于恢复星系的固有的，吸收校正的表面亮度分布，并将该模型应用于M31。我们构造了一个由轴对称恒星成分和尘埃盘叠加而成的星系模型来分析内禀吸收效应。尘埃柱的密度被认为与星系的远红外线通量成正比。沿着每一条视线，所观察到的远红外光谱能量分布近似与修改后的黑体函数，考虑不同温度的尘埃成分，允许确定的尘埃成分的温度和相对柱密度。我们将该模型应用到附近的星系M31使用斯皮策太空望远镜远红外观测映射尘埃分布和温度。一个温暖的和一个冷的尘埃成分被区分。M31中温暖尘埃的温度在56至60 K之间变化，在旋臂中最高;冷成分的温度大多在15至19 K之间，在星系中心上升到约25 K。尘埃的强度加权平均温度从中心的T ~32 K降低到R ~7 kpc和向外的T ~20 K。计算了UBVRIL内禀表面亮度分布和空间亮度分布。V色的固有尘埃消光从中心的0.25等上升到R = 6-13 kpc的0.4-0.5等，此后平稳下降。计算得到M31的总光度为L_B =（3.64 pm 0.15）10^10L_sun，对应于绝对光度M_B =（-20.89 pm 0.04）mag。在我们的最佳拟合模型中，凸起的固有形状略长。
英文摘要：
We create a model for recovering the intrinsic, absorption-corrected surface brightness distribution of a galaxy and apply the model to the M31. We construct a galactic model as a superposition of axially symmetric stellar components and a dust disc to analyse the intrinsic absorption efects. Dust column density is assumed to be proportional to the far-infrared flux of the galaxy. Along each line of sight, the observed far-infrared spectral energy distribution is approximated with modified black body functions considering dust components with different temperatures, allowing to determine the temperatures and relative column densities of the dust components. We apply the model to the nearby galaxy M31 using the Spitzer Space Telescope far-infrared observations for mapping dust distribution and temperature. A warm and a cold dust component are distinguished. The temperature of the warm dust in M31 varies between 56 and 60 K and is highest in the spiral arms; the temperature of the cold component is mostly 15-19 K and rises up to about 25 K at the centre of the galaxy. The intensity-weighted mean temperature of the dust decreases from T ~32 K at the centre to T ~20 K at R ~7 kpc and outwards. We also calculate the intrinsic UBVRIL surface brightness distributions and the spatial luminosity distribution. The intrinsic dust extinction in the V-colour rises from 0.25 mag at the centre to 0.4-0.5 mag at R = 6-13 kpc and decreases smoothly thereafter. The calculated total extinction-corrected luminosity of M31 is L_B = (3.64 pm 0.15) 10^10L_sun, corresponding to an absolute luminosity M_B = (-20.89 pm 0.04) mag. Of the total B-luminosity, 20% (0.24 mag) is obscured from us by the dust inside M31. The intrinsic shape of the bulge is slightly prolate in our best-fit model.
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