A simple model for the relationship between star formation and surface density
A simple model for the relationship between star formation and surface density
复制标题
恒星形成与表面密度之间关系的简单模型
DOI：
10.1111/j.1365-2966.2009.14815.x
复制
发表时间：
2009
影响因子：
4.8
通讯作者：
J. Pringle
中科院分区：
文献类型：
--
作者：
C. Dobbs;J. Pringle
我们研究了单位面积恒星形成率与星际介质表面密度(ISM；（局部kennicutschmitt定律）)使用ISM的简化模型和基于结合团块中的气体质量，团块的局部动态时间尺度和约∈≈5%的效率参数的恒星形成率的简单估计。尽管方法简单，我们能够重现观察到的恒星形成率与致密（分子）气体表面密度之间的线性关系。我们使用一个简单的模型来解释h2分数对总表面密度的依赖性，以说明为什么总表面密度和h2表面密度都不是恒星形成率的良好局部指标。我们还研究了恒星形成速率与螺旋势深度的关系。我们的模型表明，平均恒星形成率并不明显依赖于螺旋势的强度，但对于给定的平均表面密度，更强的螺旋势确实导致更多的恒星形成发生在靠近螺旋臂的地方。这与观测结果一致，即与絮状星系相比，大设计星系似乎没有显示出更大程度的恒星形成。
We investigate the relationship between the star formation rate per unit area and the surface density of the interstellar medium (ISM; the local Kennicutt―Schmitt law) using a simplified model of the ISM and a simple estimate of the star formation rate based on the mass of gas in bound clumps, the local dynamical time-scales of the clumps and an efficiency parameter of around ∈ ≈ 5 per cent. Despite the simplicity of the approach, we are able to reproduce the observed linear relation between star formation rate and surface density of dense (molecular) gas. We use a simple model for the dependence of H 2 fraction on total surface density to argue why neither total surface density nor the H I surface density is a good local indicator of star formation rate. We also investigate the dependence of the star formation rate on the depth of the spiral potential. Our model indicates that the mean star formation rate does not depend significantly on the strength of the spiral potential, but that a stronger spiral potential, for a given mean surface density, does result in more of the star formation occurring close to the spiral arms. This agrees with the observation that grand design galaxies do not appear to show a larger degree of star formation compared to their flocculent counterparts.