The stellar, gaseous and young stellar disks in the LITTLE THINGS sample of nearby dIrrs are fitted with functions to search for correlations between the parameters. We find that the HI radial profiles are generally flatter in the center and fall faster in the outer regions than the V-band profiles, while young stars are more centrally concentrated, especially if the HI is more centrally flat. This pattern suggests that the HI is turning into molecules in the center and the molecular clouds are forming stars and FUV. A model that assumes the molecular surface density is proportional to the total gas surface density to a power of 1.5 or 2, in analogy with the Kennicutt-Schmidt relation, reproduces the relationship between the ratio of the visible to the HI scale length and the HI Sersic index. The molecular fraction is estimated as a function of radius for each galaxy by converting the FUV to a molecular surface density using conventional calibrations. The average molecular fraction inside 3R_D is 23+/-17%. However, the break in the stellar surface brightness profile has no unified tracer related to star formation.

中文翻译：

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矮不规则星系中恒星、气体和恒星形成盘之间的关系：暗分子气体大量分数的间接证据

附近 dIrrs 的 LITTLE THINGS 样本中的恒星、气态和年轻恒星盘都装有函数以搜索参数之间的相关性。我们发现 HI 径向剖面通常在中心更平坦，在外围区域比 V 带剖面下降得更快，而年轻的恒星更集中，特别是如果 HI 中心更平坦。这种模式表明 HI 正在变成中心的分子，分子云正在形成恒星和 FUV。假设分子表面密度与总气体表面密度成 1.5 或 2 的幂的模型，类似于 Kennicutt-Schmidt 关系，再现了可见光与 HI 标度长度之比与 HI 之间的关系服务指数。通过使用常规校准将 FUV 转换为分子表面密度，分子分数被估计为每个星系半径的函数。3R_D 内的平均分子分数为 23+/-17%。然而，恒星表面亮度剖面的断裂并没有与恒星形成相关的统一示踪剂。