Coronagraphic near-IR photometry of AB Doradus C
Coronagraphic near-IR photometry of AB Doradus C
复制标题
AB Doradus C 的冠状近红外光度测定
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
J. Beuzit
中科院分区：
文献类型：
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作者：
A. Boccaletti;G. Chauvin;P. Baudoz;J. Beuzit
上下文观测低质量的同伴，动力学质量得到很好的约束，有助于提高演化模型的校准。因此，这种观测为使用下一代行星探测器仪器预期采用的光度测量方法估计伴星质量提供了更大的信心。目标。在甚大望远镜（VLT）上调试一个新的日冕仪是在著名的物体AB Dor A及其0.09 M伴星AB Dor C上测试这一技术性能的机会。本文的目的是完善这一目标的光度分析，并提供一个准确的光度误差预算。方法.除了日冕测量外，我们还用参考星星标定了剩余的恒星晕。我们使用标准技术进行光度提取。结果伴星AB Dor C很容易在距离主星星星0.185 λ的位置被发现，它的H和Ks等与M 5.5天体一致，这是光谱观测中已知的。然而，这些新的测量使早期的J波段测光不太可靠。最后，与进化模型的比较支持（75 ± 25）万年的年龄，与以前的分析相反。这些观测结果表明，日冕观测可以比直接成像更有效，不仅可以提高对比度，而且只要实现良好的恒星晕校准，就可以提供更好的光度估计。
Context. Observations of low-mass companions for which the dynamical masses are well constrained help to improve the calibration of evolutionary models. Such observations thereby provide more confidence in the estimation of the mass of a companion using the photometric methods expected for the next generation of planet finder instruments. Aims. The commissioning of a new coronagraph at the Very Large Telescope (VLT) was the occasion to test the performance of this technique on the well-known object AB Dor A and its 0.09 Mcompanion AB Dor C. The purpose of this paper is to refine the photometric analysis on this object and to provide an accurate photometric error budget. Methods. In addition to coronagraphy, we calibrated the residual stellar halo with a reference star. We used standard techniques for photometric extraction. Results. The companion AB Dor C is easily detected at 0.185 �� from the primary star, and its magnitudes in H and Ks are in agreement with an M 5.5 object, as already known from spectroscopic observations. However, these new measurements make the earlier J-band photometry less reliable. Finally, the comparison with evolutionary models supports an age of (75 ± 25) Myr, contrary to previous analyses. These observations demonstrate that coronagraphic observations can be more efficient than direct imaging, not only to improve contrast, but also to provide a better photometric estimation as long as a good calibration of the stellar halo is achieved.