微透镜事件中二进制系统中棕色矮人质量的精确度量OGLE-2019-BLG-0033/MOA-2019-BLG-035

论文标题

微透镜事件中二进制系统中棕色矮人质量的精确度量OGLE-2019-BLG-0033/MOA-2019-BLG-035

Precision measurement of a brown dwarf mass in a binary system in the microlensing event OGLE-2019-BLG-0033/MOA-2019-BLG-035

论文作者

Herald, A., Udalski, A., Bozza, V., Rota, P., Bond, I. A., Yee, J. C., Sajadian, S., Mroz, P., Poleski, R., Skowron, J., Szymanski, M. K., Soszynski, I., Pietrukowicz, P., Kozlowski, S., Ulaczyk, K., Rybicki, K. A., Iwanek, P., Wrona, M., Gromadzki, M., Abe, F., Barry, R., Bennett, D. P., Bhattacharya, A., Fukui, A., Fujii, H., Hirao, Y., Itow, Y., Kirikawa, R., Kondo, I., Koshimoto, N., Matsubara, Y., Matsumoto, S., Miyazaki, S., Muraki, Y., Olmschenk, G., Ranc, C., Okamura, A., Rattenbury, N. J., Satoh, Y., Sumi, T., Suzuki, D., Silva, S. Ishitani, Toda, T., Tristram, P. J., Vandorou, A., Yama, H., Beichman, C. A., Bryden, G., Novati, S. Calchi, Carey, S., Gaudi, B. S., Gould, A., Henderson, C. B., Johnson, S., Shvartzvald, Y., Zhu, W., Dominik, M., Hundertmark, M., Jorgensen, U. G., Longa-Pena, P., Skottfelt, J., Tregloan-Reed, J., Bach-Moller, N., Burgdorf, M., D'Ago, G., Haikala, L., Hitchcock, J., Khalouei, E., Peixinho, N., Rahvar, S., Snodgrass, C., Southworth, J., Spyratos, P., Zang, W., Yang, H., Mao, S., Bachelet, E., Maoz, D., Street, R. A., Tsapras, Y., Christie, G. W., Cooper, T., de Almeida, L., Nascimento Jr, J. -D. do, Green, J., Han, C., Hennerley, S., Marmont, A., McCormick, J., Monard, L. A. G., Natusch, T., Pogge, R.

论文摘要

语境。棕色矮人是恒星和行星之间的过渡对象知之甚少，已经提出了几种相互竞争的机制来形成。对于孤立的物体而言，通常很难进行质量测量，但对于绕着低质量恒星绕的棕色矮人来说，质量测量通常对于光谱的随访通常太微弱。目标。微透镜为发现和研究这种淡淡的系统提供了替代工具。在这里，我们介绍了微透明事件OGLE-2019-BLG-0033/MOA-2019-BLG-035的分析，这是由于二进制系统由Brown Dwarf绕着红色矮人绕的二进制系统所致。方法。得益于广泛的地面观测和Spitzer的空间观测，可以获得所有微透镜参数的准确估计，包括视差，源半径和二进制镜头的轨道运动。结果。经过准确的建模之后，我们发现镜头由质量$ $ m_1 = 0.149 \ pm 0.010m_ \ odot $和一个带质量$ $ $ m_2 = 0.0463 \ pm 0.0031m_ \ odot $的棕色矮人组成的红色矮人\ odot $ 0.010m_ \ odot $和brown dwarf，预计分离为$ a_ \ a_ \ per perp = 0.585 $ au。该系统具有奇特的速度，是厚磁盘中旧金属贫困种群的典型速度。棕色矮人的质量测量中的精度百分比仅在到目前为止的几个微透镜事件中才达到，但可能与罗马太空望远镜变得普遍。

Context. Brown dwarfs are poorly understood transition objects between stars and planets, with several competing mechanisms having been proposed for their formation. Mass measurements are generally difficult for isolated objects but also for brown dwarfs orbiting low-mass stars, which are often too faint for spectroscopic follow-up. Aims. Microlensing provides an alternative tool for the discovery and investigation of such faint systems. Here we present the analysis of the microlensing event OGLE-2019-BLG-0033/MOA-2019-BLG-035, which is due to a binary system composed of a brown dwarf orbiting a red dwarf. Methods. Thanks to extensive ground observations and the availability of space observations from Spitzer, it has been possible to obtain accurate estimates of all microlensing parameters, including parallax, source radius and orbital motion of the binary lens. Results. After accurate modeling, we find that the lens is composed of a red dwarf with mass $M_1 = 0.149 \pm 0.010M_\odot$ and a brown dwarf with mass $M_2 = 0.0463 \pm 0.0031M_\odot$, at a projected separation of $a_\perp = 0.585$ au. The system has a peculiar velocity that is typical of old metal-poor populations in the thick disk. Percent precision in the mass measurement of brown dwarfs has been achieved only in a few microlensing events up to now, but will likely become common with the Roman space telescope.

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