Distances to dense cores that contain very low luminosity objects
Distances to dense cores that contain very low luminosity objects
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DOI：
10.1051/0004-6361/201116438
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发表时间：
2011-10
影响因子：
6.5
通讯作者：
G. Maheswar;C. Lee;S. Dib
中科院分区：
文献类型：
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作者：
G. Maheswar;C. Lee;S. Dib
该论文的目的是估计斯皮策太空望远镜探测到的含有极低光度天体（VeLLO）的致密分子核心的距离，并确认它们的VeLLO性质。用近红外光度法估算了云的距离。我们使用的技术，提供光谱分类的恒星躺在对领域包含云到主序星和巨星。在这种方法中，观测到的（J-H）色和（H-Ks）色是用A_V的试验值和正常的星际消光定律同时去红的。去红颜色与内禀颜色的最佳拟合给出了最小的chi^{2}值，然后产生了星星相应的光谱类型和A_V。这样分类的主序星，然后在A_V与距离图中使用，以包含云的距离。利用该方法估算了IRAM 04191、L1521 F、BHR 111、L328、L 673 -7、L1014和L1148等7个云核的距离。这些云包含VeLLO候选者。到堆芯的估计距离为127\pm25 pc（IRAM 04191）、136\pm36 pc（L1521 F）、355\pm65 pc（BHR 111）、217\pm30 pc（L328）、240\pm45 pc（L 673 -7）、258\pm50 pc（L1014）和301\pm55 pc（L1148）。我们使用这项工作估计的距离重新评估了在这七个云中发现的VeLLO的内部光度。除L1014-IRS（L_{int}=0.15 L_{\odot}）外，其他所有候选VeLLO都符合VeLLO（L_{int}<=0.1L_{\odot}）的定义。除了包含VeLLO候选者的核心之外，我们还获得了位于上述七个核心方向上的云L323，L 675，L 676，CB 188，L1122，L1152，L1155，L1157和L1158的距离。在L1521 F和L1148附近，我们发现了多个尘埃层存在的证据。
The aim of the paper is to estimate distances to dense molecular cores that harbour Very Low Luminosity Objects (VeLLO) detected by Spitzer Space Telescope and to confirm their VeLLO nature. The cloud distances are estimated using near-IR photometric method. We use a technique that provides spectral classification of stars lying towards the fields containing the clouds into main sequence and giants. In this technique, the observed (J-H) and (H-Ks) colours are dereddened simultaneously using trial values of A_V and a normal interstellar extinction law. The best fit of the dereddened colours to the intrinsic colours giving a minimum value of chi^{2} then yields the corresponding spectral type and A_V for the star. The main sequence stars, thus classified, are then utilized in an A_V versus distance plot to bracket the cloud distances. The typical error in the estimation of distances to the clouds are found to be ~18%.We estimated distances to seven cloud cores, IRAM04191, L1521F, BHR111, L328, L673-7, L1014, and L1148 using the above method. These clouds contain VeLLO candidates. The estimated distances to the cores are found to be 127\pm25 pc (IRAM04191), 136\pm36 pc (L1521F), 355\pm65 pc (BHR111), 217\pm30 pc (L328), 240\pm45 pc (L673-7), 258\pm50 pc (L1014), and 301\pm55 pc (L1148). We re-evaluated the internal luminosities of the VeLLOs discovered in these seven clouds using the distances estimated from this work. Except for L1014-IRS (L_{int}=0.15 L_{\odot}), all other VeLLO candidates are found to be consistent with the definition of a VeLLO (L_{int}<=0.1L_{\odot}). In addition to the cores that harbour VeLLO candidates, we also obtained distances to the clouds L323, L675, L676, CB 188, L1122, L1152, L1155, L1157 and L1158 which are located in the directions of the above seven cores. Towards L1521F and L1148 we found evidence of the presence of multiple dust layers.