标题： M100盘面和旋臂中恒星、气体和尘埃的全局形态及其物理关系 显示英文标题

标题： Global morphology and physical relations between the stars, gas and dust in the disc and arms of M100

摘要： 我们研究了弱棒状大设计旋涡星系M100（NGC 4321）盘中的恒星形成过程，利用了多种图像来追踪近期的大质量恒星形成、老年和年轻恒星、尘埃以及中性氢。 通过将图像分解为旋臂区和非旋臂区，专门研究了旋臂区与非旋臂区之间的差异。 通过对H$\alpha$、HI和尘埃形态的比较发现，虽然前两者在盘的大部分区域一致，但它们与尘埃带尤其是旋臂内侧部分存在偏移：这一图景表明密度波激波正穿过旋臂。 HI是在年轻的大质量恒星附近由于光解作用而形成的。 从径向剖面来看，我们在恒星形成旋臂区域发现H$\alpha$、蓝光和近红外光以及21厘米射电连续谱的指数尺度长度在拟合误差范围内相等。 非旋臂区的尺度长度对于所有这些示踪剂也相等，但旋臂区的尺度长度显著更长。 这表明恒星形成过程中这些剖面具有共同起源，受到径向人口梯度或该星系盘中尘埃的影响很小或几乎没有影响。 较长的旋臂尺度长度相当于旋臂与非旋臂对比度的向外增加。 我们提出无线电连续谱和HI以及CO的径向剖面也直接受恒星形成调控，并讨论了这一结果对解释旋臂内外观测到的CO强度可能的意义。 我们详细讨论了径向原子氢剖面。 在恒星形成旋臂区域，其几乎完美的平坦形状可以通过光解离和再结合过程，在有限条件下得到解释。 显示英文摘要

摘要： We study star formation processes in the disc of the weakly barred grand design spiral galaxy M100 (NGC 4321) from a variety of images tracing recent massive star formation, old and young stars, dust, and neutral hydrogen. Differences between arm and interarm regions are specifically studied by decomposing the images into arm and non-arm zones. We find from a comparison of the morphology in H$\alpha$, HI and dust that while the first two are coincident over most of the disc, they are offset from the dust lanes especially along the inner parts of the spiral arms: a picture which is indicative of a density wave shock moving through the arms. HI is formed near the young massive stars as a result of photo-dissociation. From radial profiles we find that in the region of the star-forming spiral arms the exponential scale lengths for H$\alpha$, blue and near-infrared light, and 21 cm radio continuum are equal within the fitting errors. The scale lengths for the interarm region are also equal for all these tracers, but the arm scale lengths are significantly longer. This points to a common origin of the profiles in star formation, with little or no influence from radial population gradients or dust in the disc of this galaxy. The longer arm scale lengths are equivalent to an outwardly increasing arm-interarm contrast. We argue that the radial profiles of radio continuum and HI, as well as CO, are also directly regulated by star formation, and discuss the possible implications of this result for the interpretation of observed CO intensities in and outside spiral arms. We discuss the radial atomic hydrogen profile in some detail. Its almost perfectly flat shape in the region of the star-forming spiral arms may be explained by photodissociation and recombination processes in the presence of a limited