标题： 大型麦哲伦云棒在NGC1854、NGC1856和NGC1858周围的 extinction 显示英文标题

标题： Extinction in the Large Magellanic Cloud Bar around NGC1854, NGC1856, and NGC1858

摘要： 我们报告了大麦哲伦星云棒上星团NGC 1854、NGC 1856和NGC 1858周围区域的消光性质。这些区域内恒星的颜色-亮度图显示了一个拉长的红巨星团块，揭示了这些区域中不同量的消光，范围从Av~0.2到Av~1.9，包括银河系前景消光。然而，消光性质在很大程度上表现出一致性。在(V-I,V)和(B-I,B)颜色-亮度平面上测量的消红化矢量的斜率完全符合在30 Dor外围发现的Av/E(B-V)~5.5值。这表明光学波段存在一个额外的灰色消光成分，需要的大颗粒数量约为弥漫银河系星际介质（ISM）中的两倍。更高消光的区域似乎系统地与更强烈的恒星形成区域相关，这是通过超过8 Msun质量恒星数量的增加来衡量的，因此超新星II型爆炸向ISM注入大颗粒很可能是观察到的灰色消光成分的起源机制。 显示英文摘要

摘要： We report on the extinction properties in the fields around the clusters NGC 1854, NGC 1856, and NGC 1858 in the bar of the Large Magellanic Cloud. The colour-magnitude diagrams of the stars in all these regions show an elongated red giant clump that reveals a variable amount of extinction across these fields, ranging from Av~0.2 to Av~1.9, including Galactic foreground extinction. The extinction properties nonetheless are remarkably uniform. The slope of the reddening vectors measured in the (V-I,V) and (B-I,B) colour-magnitude planes is fully in line with the Av/E(B-V)~5.5 value found in the outskirts of 30 Dor. This indicates the presence of an additional grey extinction component in the optical requiring big grains to be about twice as abundant as in the diffuse Galactic interstellar medium (ISM). Areas of higher extinction appear to be systematically associated with regions of more intense star formation, as measured by the larger number of stars more massive than 8 Msun, thus making injection of big grains into the ISM by SNII explosion the likely mechanism at the origin of the observed grey extinction component.