Imaged Exoplanets(成像的系外行星)研究综述
Imaged Exoplanets 成像的系外行星 - Many exoplanet-focused instruments use a lenslet IFS to make datacubes with spatial and spectral information used to extract spectral information of imaged exoplanets. [1]许多系外行星聚焦仪器使用小透镜 IFS 制作具有空间和光谱信息的数据立方体，用于提取成像系外行星的光谱信息。 [1]
Directly Imaged Exoplanets 直接成像的系外行星
Measuring the orbits of directly imaged exoplanets requires precise astrometry at the milliarcsec level over long periods of time due to their wide separation to the stars (≳10 au) and long orbital period (≳20 yr). [1] Measurements of the transmission spectra, dayside emission, and phase curves of transiting exoplanets, as well as the emission spectrum and light curves of directly imaged exoplanets and brown dwarfs have shown that aerosols are distributed inhomogeneously in exoplanet atmospheres, with aerosol distributions varying significantly with planet equilibrium temperature and gravity. [2] These are the most challenging directly imaged exoplanets that have been observed at high spectral resolution to date when considering both their angular separations and flux ratios. [3] ExoSpec Project is a NASA Headquarters directed work package that links four different tasks at Goddard space flight center to enable future missions to more efficiently characterize directly imaged exoplanets. [4] We measured the near-infrared linear polarization of 20 known directly imaged exoplanets and brown dwarf companions with the high-contrast imager SPHERE-IRDIS at the VLT. [5] The aim of this project is to investigate biases (deviation of the median and mode of the posterior from the true values of orbital parameters, and the width and coverage of their credible intervals) in the estimation of orbital parameters of directly imaged exoplanets, particularly their eccentricities, and to define general guidelines to perform better estimations of uncertainty. [6] Likewise, it suggests that stable and large scale cloud covers could be ubiquitous in strongly irradiated exoplanets but might be more patchy in low-irradiated or isolated objects like brown dwarfs and directly imaged exoplanets. [7] We suggest that directly imaged exoplanets at large orbital radii, where the disk mass criterion is more likely to be satisfied, could have significant obliquities due to the tilt instability of their circumplanetary disks. [8] The main reason behind the small number of directly imaged exoplanets is that such observations are extremely challenging. [9] Atmospheric characterization of directly imaged exoplanets is currently limited to Giant planets and Mini-Neptunes. [10] The Keck Planet Imager and Characterizer (KPIC) is a novel instrument that combines high-contrast imaging with high-resolution spectroscopy to enable high-dispersion coronagraphy (HDC) techniques that allow us to characterize directly imaged exoplanets at a spectral resolution of R~35,000. [11] In the near term, it will be used to spectrally characterize known directly imaged exoplanets and low-mass brown dwarf companions visible in the northern hemisphere with a spectral resolution high enough to enable spin and planetary radial velocity measurements as well as Doppler imaging of atmospheric weather phenomena. [12] Current and future high-contrast imaging instruments require extreme adaptive optics systems to reach contrasts necessary to directly imaged exoplanets. [13] Reflected starlight measurements will open a new path in the characterization of directly imaged exoplanets. [14] The orbital eccentricities of directly imaged exoplanets and brown dwarf companions provide clues about their formation and dynamical histories. [15] Although HR 8799 e was already known, the interferometry technique could be used to refine the orbits and spectra of directly imaged exoplanets. [16] KPIC will enable High Dispersion Coronagraphy (HDC) of directly imaged exoplanets for the first time, providing potentially improved detection significance and spectral characterization capabilities compared to direct imaging. [17] In this work, we show how it can be used to derive radial velocity (RV) measurements of directly imaged exoplanets. [18]测量直接成像的系外行星的轨道需要在很长一段时间内进行精确的天体测量，因为它们与恒星的距离很远（≳10 au）和较长的轨道周期（≳20 yr）。 [1] 对凌日系外行星的透射光谱、白天发射和相位曲线的测量，以及直接成像的系外行星和褐矮星的发射光谱和光变曲线的测量表明，气溶胶在系外行星大气中分布不均匀，气溶胶分布随行星的变化而显着平衡温度和重力。 [2] 这些是迄今为止在高光谱分辨率下观察到的最具挑战性的直接成像系外行星，同时考虑到它们的角间距和通量比。 [3] ExoSpec 项目是 NASA 总部指导的工作包，将戈达德太空飞行中心的四个不同任务联系起来，以使未来的任务能够更有效地表征直接成像的系外行星。 [4] 我们用 VLT 的高对比度成像仪 SPHERE-IRDIS 测量了 20 颗已知的直接成像系外行星和褐矮星伴星的近红外线性偏振。 [5] 该项目的目的是研究直接成像系外行星轨道参数估计中的偏差（中值和后验模式与轨道参数真实值的偏差，以及可信区间的宽度和覆盖范围），尤其是它们的轨道参数。偏心率，并定义一般准则以更好地估计不确定性。 [6] 同样，它表明稳定和大规模的云层覆盖在受到强烈辐照的系外行星中可能无处不在，但在低辐照或孤立的物体（如褐矮星和直接成像的系外行星）中可能更加零散。 [7] 我们建议，在大轨道半径处直接成像的系外行星更可能满足圆盘质量标准，由于其环绕行星盘的倾斜不稳定性，它们可能具有显着的倾角。 [8] 少量直接成像的系外行星背后的主要原因是此类观测极具挑战性。 [9] 直接成像系外行星的大气特征目前仅限于巨行星和迷你海王星。 [10] 凯克行星成像仪和表征器 (KPIC) 是一种新型仪器，它将高对比度成像与高分辨率光谱相结合，以实现高色散日冕成像 (HDC) 技术，使我们能够以 R~35,000 的光谱分辨率表征直接成像的系外行星. [11] 在短期内，它将用于对已知的直接成像系外行星和在北半球可见的低质量褐矮星伴星进行光谱表征，其光谱分辨率足以实现自旋和行星径向速度测量以及大气天气的多普勒成像现象。 [12] 当前和未来的高对比度成像仪器需要极端的自适应光学系统来达到直接成像系外行星所需的对比度。 [13] 反射星光测量将为直接成像的系外行星的表征开辟一条新途径。 [14] 直接成像的系外行星和褐矮星伴星的轨道偏心率为它们的形成和动力学历史提供了线索。 [15] 尽管 HR 8799 e 已经为人所知，但干涉测量技术可用于细化直接成像的系外行星的轨道和光谱。 [16] 大韩油化将首次实现直接成像系外行星的高色散日冕成像（HDC），与直接成像相比，提供潜在改进的探测意义和光谱表征能力。 [17] 在这项工作中，我们展示了如何使用它来导出直接成像的系外行星的径向速度 (RV) 测量值。 [18]