THE INITIAL MASS FUNCTION AND YOUNG BROWN DWARF CANDIDATES IN NGC 2264. III. PHOTOMETRIC DATA
THE INITIAL MASS FUNCTION AND YOUNG BROWN DWARF CANDIDATES IN NGC 2264. III. PHOTOMETRIC DATA
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NGC 2264 中的初始质量函数和年轻褐矮星候选者。
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
M. Ibrahimov
中科院分区：
文献类型：
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作者：
H. Sung;M. Bessell;M. Chun;R. Karimov;M. Ibrahimov
我们对年轻疏散星团NGC 2264进行了深宽视场CCD测光，以研究恒星形成区（SFR）的范围和初始质量函数的形状。本文介绍了67，000多颗恒星的VRI和Hα测光。从所选的Hα发射星的空间分布，我们确定了两个活跃的SFR和一个不太活跃的晕区围绕这两个SFR。在晕区之外的场区有几颗Hα发射星，它们可能是围绕星团的Mon OB 1星协中的新形成恒星。根据Hα和X射线辐射星在IC-V-IC图中的分布，修正了PMS星在IC-V-IC图中的轨迹。利用2 MASS色图中X射线发射星的分布，晚型PMS星的平均红化估计为E（B）<$0.2等。从它们的空间分布以及在2 MASS色图中的近红外过量，我们可以确认PMS轨迹以下的Hα发射星（所谓的BMS星）是NGC 2264的真正成员。此外，斯皮策IRAC探测到的IRS-2周围的四个物体也被归类为BMS星。
We have performed deep wide-field CCD photometry of the young open cluster NGC 2264 to study the extent of star-forming regions (SFRs) and the shape of the initial mass function. In this paper, we present VRI and Hα photometry for more than 67,000 stars. From the spatial distribution of the selected Hα emission stars, we identify two active SFRs and a less active halo region surrounding these two SFRs. There are several Hα emission stars in the field region outside the halo region, and these may be newly formed stars in the Mon OB1 association surrounding the cluster. The locus of pre-main-sequence (PMS) stars in the IC versus V − IC diagram is revised from the distribution of Hα and X-ray emission stars in the diagram. The mean reddening of late-type PMS stars is estimated to be E(B − V) ≈ 0.2 mag using the distribution of X-ray emission stars in the 2MASS color–color diagram. We can confirm that the Hα emission stars below the PMS locus (so-called BMS stars) are bona-fide members of NGC 2264 from their spatial distribution as well as from their near-IR excess in the 2MASS color–color diagram. In addition, four objects around IRS-2 detected with the Spitzer IRAC are also classified as BMS stars.