论文标题
NGC 1938年异常灭绝
Anomalous extinction towards NGC 1938
论文作者
论文摘要
在50x50 pc^2的恒星上伸展的延伸红色巨型团块（RC）在大型麦哲伦云（LMC）中伸展的恒星图（LMC），其中包含簇NGC 1938和NGC 1939，我们已经研究了Stellar种群，以了解该领域的属性（ISSMED）（ISSM）（ISSM）（ISM）（ISM）（ISM）（ISM）（ISM）（ISM）。扩展的RC是由整个场上大量灭绝量引起的。它的斜率揭示了异常的灭绝特性，AV/E（B-V）= 4.3，表明光学中存在额外的灰色成分，占该田间总灭绝的约30％，并且要求大晶粒的大约两倍，大约是弥漫性ISM中的两倍。这似乎与大约70张SNII爆炸注入周围ISM的大谷物数量是一致的，估计发生在〜120 Myr NGC 1938的一生中发生的大约发生的爆炸量。尽管该群集今天相对较小，并且很难检测到M 31的距离，并且在M 31的距离之外，估计的初始质量是〜4800 MSUN NGC 1933年的范围，该群体的范围很难。这对附近和早期宇宙中的恒星形成星系的亮度和质量的解释具有重要意义。
Intrigued by the extended red-giant clump (RC) stretching across the colour-magnitude diagram of the stars in a 50x50 pc^2 region of the Large Magellanic Cloud (LMC) containing the clusters NGC 1938 and NGC 1939, we have studied the stellar populations to learn about the properties of the interstellar medium (ISM) in this area. The extended RC is caused by a large and uneven amount of extinction across the field. Its slope reveals anomalous extinction properties, with Av/E(B-V)=4.3, indicating the presence of an additional grey component in the optical contributing about 30% of the total extinction in the field and requiring big grains to be about twice as abundant as in the diffuse ISM. This appears to be consistent with the amount of big grains injected into the surrounding ISM by the about 70 SNII explosions estimated to have occurred during the lifetime of the ~120 Myr old NGC 1938. Although this cluster appears today relatively small and would be hard to detect beyond the distance of M 31, with an estimated initial mass of ~4800 Msun NGC 1938 appears to have seriously altered the extinction properties in a wide area. This has important implications for the interpretation of luminosities and masses of star-forming galaxies, both nearby and in the early universe.
