2007年恒星初始质量函数：发现变化的一年
The Stellar Initial Mass Function in 2007: A Year for Discovering Variations
摘要：
评述了星系团、场区、星系和宇宙学时期形成的场区的IMF特征质量M_c和斜率γ。局部恒星形成具有较均匀的M_c和γ。总结了Gamma的统计变化，以及这些变化带来的限制。宇宙学恒星形成似乎在中到高恒星质量处具有较高的M_c和稍浅的斜率。银河系的中心可能也有一个浅的斜坡。场区的斜率比星团稍陡，但这可能是低质量恒星从星团和星协中漂移出来的结果。矮星系也有更陡的斜坡。还回顾了星前团块的观测结果。星前团块似乎具有与恒星相同的质量函数，因此被认为是恒星的主要前身。如果是这种情况，那么IMF通常由气相过程决定。褐矮星的形成也有许多恒星形成的特征，这表明它们的形成机制相似。
英文摘要：
The characteristic mass M_c and slope Gamma of the IMF are reviewed for clusters, field regions, galaxies, and regions formed during cosmological times. Local star formation has a somewhat uniform M_c and Gamma. Statistical variations in Gamma are summarized, as are the limitations imposed by these variations. Cosmological star formation appears to have both a higher M_c and a slightly shallower slope at intermediate to high stellar mass. The center of the Milky Way may have a shallow slope too. Field regions have slightly steeper slopes than clusters, but this could be the result of enhanced drift of low mass stars out of clusters and associations. Dwarf galaxies also have steeper slopes. Results from the observation of pre-stellar clumps are reviewed too. Pre-stellar clumps appear to have about the same mass function as stars and are therefore thought to be the main precursors to stars. If this is the case, then the IMF is generally determined by gas-phase processes. Brown dwarf formation also shares many characteristics of star formation, suggesting that they form by similar mechanisms.
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