标题： 尘埃风成气泡 显示英文标题

标题： Dusty Wind-Blown Bubbles

摘要： 受最近对风成气泡内24微米辐射的观测启发，我们研究了尘埃在这些环境中可能起到的作用，并建立了一个特定风成气泡`N49'的近似模型。 首先，我们用带有尘埃的风成气泡来模拟观测结果，然后询问尘埃是否能够在N49中存活到其目前的年龄（估计为5x10^5至10^6年）。 我们发现，尘埃溅射以及特别是尘埃-气体摩擦会导致气泡风冲击区域中的尘埃存活时间相对较短（t ~ 10^4年）。 为了解释24微米辐射，我们假设颗粒通过被扩张的风成气泡覆盖的嵌入致密星际介质气体云团的破坏而在风成气泡内得到补充。 我们计算了N49内云团的剥蚀时间尺度，并找到了能够补充尘埃的嵌入云团的大致参数；这些云团的参数大致类似于其他星云中观察到的参数。 这种尘埃会对气泡产生重要影响：包括简单的尘埃冷却在风成气泡模型中对于N49，我们发现大约10^4年的气泡年龄时光度大约提高了六倍。 在10^7年的年龄时，如果包含尘埃，气泡中的能量大约降低了八倍；如果尘埃必须在气泡内得到补充，相关的伴随气体质量也将对风成气泡的冷却和演化非常重要。 虽然显然需要更详细模型，但这项工作说明了尘埃在风成气泡中的可能重要作用，并是建立尘埃丰富的风成气泡模型的第一步。 显示英文摘要

摘要： Spurred by recent observations of 24 micron emission within wind-blown bubbles, we study the role that dust can play in such environments, and build an approximate model of a particular wind-blown bubble, `N49.' First, we model the observations with a dusty wind-blown bubble, and then ask whether dust could survive within N49 to its present age (estimated to be 5x10^5 to 10^6 years). We find that dust sputtering and especially dust-gas friction would imply relatively short timescales (t ~ 10^4 years) for dust survival in the wind-shocked region of the bubble. To explain the 24 micron emission, we postulate that the grains are replenished within the wind-blown bubble by destruction of embedded, dense cloudlets of ISM gas that have been over-run by the expanding wind-blown bubble. We calculate the ablation timescales for cloudlets within N49 and find approximate parameters for the embedded cloudlets that can replenish the dust; the parameters for the cloudlets are roughly similar to those observed in other nebula. Such dust will have an important effect on the bubble: including simple dust cooling in a wind-blown bubble model for N49, we find that the luminosity is higher by approximately a factor of six at a bubble age of about 10^4 years. At ages of 10^7 years, the energy contained in the bubble is lower by about a factor of eight if dust is included; if dust must be replenished within the bubble, the associated accompanying gas mass will also be very important to wind-blown bubble cooling and evolution. While more detailed models are certainly called for, this work illustrates the possible strong importance of dust in wind-blown bubbles, and is a first step toward models of dusty, wind-blown bubbles.