论文标题
作为动力标志的天文加速度：髋关节发现和表征21152 b，hyades中的第一个t-warf伴侣
Astrometric Accelerations as Dynamical Beacons: Discovery and Characterization of HIP 21152 B, the First T-Dwarf Companion in the Hyades
论文作者
论文摘要
具有明确确定年龄的基准棕色矮人矮人是测试实体进化模型并探测巨型行星和棕色矮人的形成的强大工具。在这里，我们报告了hip〜21152〜b的独立发现，这是hyades中第一个成像的棕色矮人伴侣，并对系统进行了全面的轨道和大气表征。 HIP〜21152的目标是在正在进行的高对比度成像运动中，在河马和盖亚之间表现出适当的运动变化，并且最近也被Bonavita等人确定。 （2022）和Kuzuhara等。 （2022）。我们的Keck/Nirc2和scexao/charis hip 〜21152的成像显示了一个共同的伴侣，分别为$ 0.37^{\ prime \ prime} $（16 au）。我们对所有可用的相对天体和径向速度的联合轨道拟合，以及河马 - 基亚的适当动作，产生的动态质量为$ 24^{+6} _ { - 4} \，\ Mathrm {m_ mathrm {m_ {jup}} $，哪个是$ 1 { - } $ 1 { - } $低于Vivolution fealt vestolution $ vestions forvivolution forvivolution forvivolution forvivolution forvivolution forvestory模型。包括云特性的演变的混合网格最能重现动态质量。我们还确定了一个共同的宽分开（$ 1837^{\ prime \ prime} $或$ 7.9 \ times 10^4 \，\ mathrm {au} $）早期l矮人，其含氢的质量在燃烧限制的极限附近，质量为质量。最后，我们使用Saumon＆Marley（2008）大气模型和一套检索套件分析了HIP〜21152〜B的光谱和光度法。最佳拟合网格的模型具有$ f _ {\ mathrm {sed}} = 2 $，表明存在云的存在，$ t _ {\ mathrm {eff}} = 1400 \，\ mathrm {k {k} $，以及$ \ log {g} = 4.5 \ f} = 4.5 \ \ \ \ \，\，\ mathrm}这些结果与对象的光谱类型的$ \ mathrm {t0 \ pm1} $一致。作为Hyades中的第一个基准棕色矮人伴侣，HIP〜21152〜B加入了较少但越来越多的具有确定年龄和动态质量的近代的替代伴侣。
Benchmark brown dwarf companions with well-determined ages and model-independent masses are powerful tools to test substellar evolutionary models and probe the formation of giant planets and brown dwarfs. Here, we report the independent discovery of HIP~21152~B, the first imaged brown dwarf companion in the Hyades, and conduct a comprehensive orbital and atmospheric characterization of the system. HIP~21152 was targeted in an ongoing high-contrast imaging campaign of stars exhibiting proper motion changes between Hipparcos and Gaia, and was also recently identified by Bonavita et al. (2022) and Kuzuhara et al. (2022). Our Keck/NIRC2 and SCExAO/CHARIS imaging of HIP~21152 revealed a comoving companion at a separation of $0.37^{\prime\prime}$ (16 au). We perform a joint orbit fit of all available relative astrometry and radial velocities together with the Hipparcos-Gaia proper motions, yielding a dynamical mass of $24^{+6}_{-4}\,\mathrm{M_{Jup}}$, which is $1{-}2σ$ lower than evolutionary model predictions. Hybrid grids that include the evolution of cloud properties best reproduce the dynamical mass. We also identify a comoving wide-separation ($1837^{\prime\prime}$ or $7.9 \times 10^4 \, \mathrm{au}$) early-L dwarf with an inferred mass near the hydrogen-burning limit. Finally, we analyze the spectra and photometry of HIP~21152~B using the Saumon & Marley (2008) atmospheric models and a suite of retrievals. The best-fit grid-based models have $f_{\mathrm{sed}}=2$, indicating the presence of clouds, $T_{\mathrm{eff}}=1400 \, \mathrm{K}$, and $\log{g}=4.5 \, \mathrm{dex}$. These results are consistent with the object's spectral type of $\mathrm{T0\pm1}$. As the first benchmark brown dwarf companion in the Hyades, HIP~21152~B joins the small but growing number of substellar companions with well-determined ages and dynamical masses.
