The structure of the cold diffuse interstellar medium
The structure of the cold diffuse interstellar medium
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冷弥漫星际介质的结构
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
P. Hily
中科院分区：
文献类型：
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作者：
E. Falgarone;F. Levrier;P. Hily
冷的弥漫星际介质（ISM）是湍流的，
超音速，很可能是横穿阿尔芬运动。所有的追踪器，
包括速度，都是以最小的尺度来构造的
可以进行观察。然而，这种结构不是随机的，
可以用它的傅里叶相位的统计来量化
增量。星际云结构的数量较多
比分形布朗运动（fBm）场和轻度
可压缩湍流我们认为这种结构是一种反应，
介质的一般性质的湍流，时空
它的消散的不稳定性。汹涌的波涛
因为他们暂时（几百年），
局部加热扩散介质到~ 103 K，不可逆
改变气体随后的热和化学演化。
这种爆发的初步模型预测了化学丰度，
激发的一个子集的分子是一致的，
意见。速度波动的时间尺度很短
足以使中性粒子与电离物质局部解耦，
扩散介质并产生螺旋磁场。小规模
扩散ISM的偏振特性的波动是
因此预期。
The cold diffuse interstellar medium (ISM) is turbulent with
supersonic, most likely transAlfvenic motions. All its tracers,
including velocity, are structured down to the smallest scales
accessible to observations. This structure, though, is not random and
can be quantified using the statistics of its Fourier phase
increments. The quantity of structure of interstellar clouds is larger
than that of fractal Brownian motion (fBm) fields and of mildly
compressible turbulence. We propose that this structure is a response
of the medium to a general property of turbulence, the space-time
intermittency of its dissipation. The bursts of turbulent
dissipation, because they temporarily (over a few hundred years) and
locally heat the diffuse medium up to ~10 3 K, irreversibly
modify the subsequent thermal and chemical evolution of the gas.
Preliminary models of such bursts predict chemical abundances and
excitation of a subset of molecules that are in agreement with the
observations. Timescales of the velocity fluctuations are short
enough to locally decouple the neutrals from the ionized species in
the diffuse medium and generate helical magnetic fields. Small scale
fluctuations of the polarization properties of the diffuse ISM are
therefore expected.