Near-Infrared Silhouette Object Survey in M17
Near-Infrared Silhouette Object Survey in M17
复制标题
DOI：
10.1086/523808
复制
发表时间：
2008
期刊：
影响因子：
--
通讯作者：
M. Ito;T. Yamashita;S. Sako;H. Takami;Y. Hayano;H. Terada
中科院分区：
文献类型：
--
作者：
M. Ito;T. Yamashita;S. Sako;H. Takami;Y. Hayano;H. Terada
为了研究年轻恒星（YSO）的包层结构是如何演化的，我们利用安装在斯巴鲁望远镜上的近红外照相机和红外照相摄谱仪对M17恒星形成区进行了JHK′波段的深成像观测。在这次调查中，我们发现了51个黑暗的轮廓，以明亮的近红外星云发射作为背景光。由于它们的大小和与YSO的关联，它们被视为与YSO相关的信封。我们推导出每个轮廓包络的大小，形态，消光和质量。包层的平均质量约为0.02 M，半径范围为1.5“至2.8”（2250-4200 Au）。我们比较了包络的性质与来自颜色-颜色和颜色-星等图的中心YSO的性质。发现包层的半径和质量随着红外过量的减少而减少，这与广泛接受的观点一致，即包层在从I类到II类的演化过程中吸积到中心星星/盘系统上。然而，这个包层仍然存在于II类天体的周围，其吸积几乎无法辨别，并且由于其昏暗，它可能已经逃脱了检测。与II类天体相关的包层可能不会吸积到星星或盘上，但它可能会在未来消散。
To study how the structure of the envelopes of young stellar objects (YSOs) evolve, we carried out a deep JHK′-band imaging survey of the M17 star-forming region using a near-infrared camera and the Infrared Camera and Spectrograph with adaptive optics mounted on the Subaru Telescope. In this survey, we found 51 dark silhouettes against bright near-infrared nebula emissions as background lights. They are regarded as envelopes associated with YSOs due to their size and association with the YSOs. We derived size, morphology, extinction, and mass for each silhouette envelope. The average mass of the envelopes was ~0.02 M☉, and the radius ranged from 1.5″ to 2.8″ (2250-4200 AU). We compared the properties of envelopes with the properties of the central YSO derived from color-color and color-magnitude diagrams. The radius and the mass of the envelope were found to decrease with the decrease in infrared excess, consistent with the widely accepted view in which the envelope accretes onto the central star/disk system during its evolution from Class I to Class II. However, the envelope still exists around the Class II object for which accretion is barely discernible, and it may have escaped detection due to its dimness. The envelope associated with Class II objects may not accrete onto the star or the disk, but it may dissipate in the future.