Non-uniform extinction in young open star clusters
Non-uniform extinction in young open star clusters
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DOI：
10.1046/j.1365-8711.2001.04754.x
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发表时间：
2001-06
影响因子：
4.8
通讯作者：
R. Yadav;R. Sagar
中科院分区：
文献类型：
--
作者：
R. Yadav;R. Sagar
研究了年轻疏散星星团NGC 663、NGC 869、NGC 884、NGC 1502、NGC 1893、NGC 2244、NGC 2264、NGC 6611、Tr 14、Tr 15、Tr 16、科尔228、Tr 37和Be 86的消光规律和色余随位置、光度和光谱类的变化。星团成员的E（B-V）的最小值和最大值之差被认为是星团内部存在非均匀气体和尘埃的一种度量。在所研究的星系团中，它的值范围从0.22到1.03等，这表明所有星系团中都存在不均匀的消光。它在NGC 1502和Tr 37中首次被发现。它还发现，在疏散星团中，这可能是由气体和尘埃的存在下，系统地减少与星团的年龄，这表明物质是用于星星的形成或吹走的热恒星或两者兼而有之。E（B-V）随位置、光谱类别或光度的变化并不均匀。除Tr 14外，所有星团的E（B-V）空间分布都是随机的，表明星团内气体和尘埃的分布是随机的。只有在科尔228、Tr 16和Be 86的情况下，E（B-V）值才与光度和光谱级有关。在λ ≥λ R时，这些团簇的成员比正常团簇的成员具有更大的色过剩比。大多数星团成员的E（U-V）/E（B-V）值接近正常的星际值1.73。然而，NGC 663、NGC 869、NGC 884和NGC 1502在λ ≥λ J时E（B-V）的色过量比小于正常值，而NGC 6611、科尔228、Tr 16和Tr 14的色过量比则大于正常值。因此，在所研究的星系团之间的消光性质的关系是不一致的。
The extinction law and the variation of colour excess with position, luminosity and spectral class in young open star clusters NGC 663, NGC 869, NGC 884, NGC 1502, NGC 1893, NGC 2244, NGC 2264, NGC 6611, Tr 14, Tr 15, Tr 16, Coll 228, Tr 37 and Be 86 have been studied. The difference in the minimum and maximum values of E ( B-V ) of cluster members has been considered as a measure of the presence of non-uniform gas and dust inside the clusters. Its value ranges from 0.22 to 1.03 mag in the clusters under study, which indicates that non-uniform extinction is present in all the clusters. It has been noticed for the first time in NGC 1502 and Tr 37. It is also found that the differential colour excess in open clusters, which may be caused by the presence of gas and dust, decreases systematically with the age of clusters, indicating that matter is either used in star formation or blown away by hot stars or both. There is no uniformity in the variation of E ( B-V ) with position or spectral class or luminosity. Except in Tr 14, all clusters show a random spatial distribution of E ( B-V ) , indicating a random distribution of gas and dust inside the clusters. TheE ( B-V) value correlates with both luminosity and spectral class only in the case of Coll 228, Tr 16 and Be 86. The members of these clusters at λ ≥λ R show larger values of colour excess ratios than the normal ones. The value of E( U- V) /E( B-V) for most of the cluster members is close to the normal interstellar value of 1.73. However, the colour excess ratios with E(B-V) at λ ≥λ J are smaller than the normal value for NGC 663, NGC 869, NGC 884 and NGC 1502, while they are larger for NGC 6611, Coll 228, Tr 16 and Tr 14. Thus there is no uniformity in the relationship of extinction properties amongst the clusters under study.