标题： 不规则星系盘中的径向丰度梯度 显示英文标题

标题： On the radial abundance gradients in disks of irregular galaxies

摘要： 我们确定了十四种属于Sm和Im类型的不规则星系（形态学T类型T = 9和T = 10）的盘状星系中由HII区所追踪的径向丰度分布。通过Te方法或者/以及对应的方法（C方法），估算出了HII区中的氧和氮丰度。此外，我们还检查了径向丰度梯度与表面亮度轮廓之间的对应关系。我们发现，具有平坦内核剖面（中心区域表面亮度平坦或向外增加）的不规则星系表现出浅薄（如果有的话）的径向丰度梯度。另一方面，具有陡峭内核剖面（带有或不带有凸起或中心恒星团）的不规则星系通常显示出相当陡峭的径向丰度梯度。这与普遍认为不规则星系通常不显示径向丰度梯度的观点相反。 显示英文摘要

摘要： We determine the radial abundance distributions across the disks of fourteen irregular galaxies of the types Sm and Im (morphological T types T = 9 and T =10) as traced by their HII regions. The oxygen and nitrogen abundances in HII regions are estimated through the Te method or/and with the counterpart method (C method). Moreover, we examine the correspondence between the radial abundance gradient and the surface brightness profile. We find that irregular galaxies with a flat inner profile (flat or outwardly increasing surface brightness in the central region) show shallow (if any) radial abundance gradients. On the other hand, irregular galaxies with a steep inner profile (with or without a bulge or central star cluster) usually show rather steep radial abundance gradients. This is in contrast to the widely held belief that irregular galaxies do not usually show a radial abundance gradient.