标题： 使用弱MgII线绘制低表面亮度星系 显示英文标题

标题： Using weak MgII lines to chart Low Surface Brightness Galaxies

摘要： 我们报告了基于哈勃太空望远镜和凯克数据，在类星体 PKS 0454+039 的 Ly-alpha 森林中检测到两个特殊的吸收体。 这些云分别位于红移 z=0.6248 和 0.9315，除了 Ly-alpha 线外，还显示出 MgII 和 FeII 吸收线。 根据光致电离模型，这些吸收体被星系间紫外背景电离，并且 HI 柱密度范围为 15.8 < N(HI) < 16.8。 此外，如果假设重元素的相对丰度类似于我们银河系中耗竭云的丰度，则这两个吸收体的丰度高于太阳值，这是与类星体无关的吸收体中的独特情况。 我们初步建议，这些吸收体可能选择巨大的低表面亮度星系。 显示英文摘要

摘要： We report the detection, based on HST and Keck data, of two peculiar absorbers in the Ly-alpha forest of the quasar PKS 0454+039. These clouds, at redshifts z=0.6248 and 0.9315 respectively, display both MgII and FeII absorption lines in addition to the Ly-alpha line. Based upon photoionization models, these are inferred to be photoionized by the intergalactic UV background, and to have HI column densities in the range 15.8 < N(HI) < 16.8. Furthermore, if one supposes that the relative abundances of heavy elements is similar to that of depleted clouds of our galaxy, the abundances of these two absorbers are greater than the solar value, which is a unique case for absorbers which are not associated to the quasar. We tentatively suggest that these absorbers may select giant low surface brightness galaxies.