Lunar occultations of 184 stellar sources in two crowded regions toward the Galactic bulge
Lunar occultations of 184 stellar sources in two crowded regions toward the Galactic bulge
复制标题
靠近银河核球的两个拥挤区域中 184 个恒星源的月掩现象
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
P. F. Wang
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作者：
A. Richichi;W. P. Chen;O. Fors;P. F. Wang
语境。月球掩星 (LO) 提供了高角分辨率和近红外波长灵敏度的独特组合。 ESO 甚大望远镜可以达到约 1 毫弧秒 (mas) 的分辨率，并探测到 K≈12 星等微弱的光源。目标。我们利用月球在银河核球内部方向上经过两个拥挤且变红的区域的机会，以获得两个半夜的大量掩星光变曲线。我们的目标是探测和表征新的双星系统，并研究高度灭绝和相对未知的红外源，以寻找星周贝壳和类似的特性。我们的目标列表包括大量非常晚期的恒星，但实际上大多数来源都没有光谱分类。方法。 LO 事件需要以毫秒速率对光变曲线进行采样，以便对衍射条纹进行详细研究。为此，我们在 Melipal 望远镜上使用了 ISAAC 仪器的所谓突发模式。我们的观测效率最终受到望远镜指向和数据存储的开销的限制，大约每三分钟一次。结果。我们可以记录 184 个光源的有用光曲线。其中，24 个被发现是双星或倍数，所有这些都是以前未知的。预计分离小至 7.5 mas，并且
Context. Lunar occultations (LO) provide a unique combination of high angular resolution and sensitivity at near-infrared wavelenghts. At the ESO Very Large Telescope, it is possible to achieve about 1 milliarcsecond (mas) resolution and detect sources as faint as K≈12 mag. Aims. We have taken advantage of a passage of the Moon over two crowded and reddened regions in the direction of the inner part of the galactic bulge , in order to obtain a high number of occultation light curves over two half nights. Our goal was to detect and characterize new binary systems, and to investigate highly extincted and relativel y unknown infrared sources in search of circumstellar shells and similar peculiarities. Our targe t list included a significant number of very late-type stars, but in fact the majority of the sources was w ithout spectral classification. Methods. A LO event requires the sampling of the light curve at millisecond rates in order to permit a detailed study of the diffraction fringes. For this, we used the so-called burst mode of the ISAAC instrument at the Melipal telescope. Our observing effi ciency was ultimately limited by overheads for telescope pointing and data storage, to about one event every three minutes. Results. We could record useful light curves for 184 sources. Of these, 24 were found to be binaries or multiples, all previously unknown. The projected separations are as small as 7.5 mas, and