A Unified Spectroscopic and Photometric Model to Infer Surface Inhomogeneity: Application to Luhman 16B
A Unified Spectroscopic and Photometric Model to Infer Surface Inhomogeneity: Application to Luhman 16B
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DOI：
10.3847/1538-4357/ac75b9
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发表时间：
2022-06
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影响因子：
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通讯作者：
M. K. Plummer;J. Wang 王
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作者：
M. K. Plummer;J. Wang 王
超大型望远镜（ELT）提供了一个机会，通过多普勒成像和分光光度技术来观察超冷物体的表面不均匀性，包括M矮星，棕矮星（BD）和气体巨行星。这些不均匀性可能是由星星斑点、云和漩涡引起的。星星斑和相关的恒星耀斑在可居住性中起着重要作用，根据发射频率，大小和方向，它们要么扼杀生命，要么催化非生物发生。云和涡旋可能是在BD的L/T转换处观察到的光谱和光度变化的来源，并且预计在气体巨型系外行星中。我们开发了一个多功能的分析框架来建模和推断表面的不均匀性，可以应用于光谱和光度数据。通过大量的数值模拟验证了该模型的有效性。使用档案光谱和光度数据，我们推断恒星黑子参数（位置，大小和对比度），并生成全球表面地图的Luhman 16 B（早期的T型矮星和我们的太阳系最近的邻居之一，距离为1.2秒差距）。我们证实了以前的研究结果，即Luhman 16 B的大气是不均匀的随时间变化的功能。此外，我们提供了较长时间尺度的大气结构，如黑暗的赤道和明亮的中纬度极地斑点的初步证据。这些发现的背景下讨论的大气环流和动力学的超冷矮星。我们的分析模型将是有价值的，在评估的可行性，使用ELTS研究气体巨系外行星和其他超冷物体的表面不均匀性。
Extremely large telescopes (ELTs) provide an opportunity to observe surface inhomogeneities for ultracool objects including M dwarfs, brown dwarfs (BDs), and gas giant planets via Doppler imaging and spectrophotometry techniques. These inhomogeneities can be caused by star spots, clouds, and vortices. Star spots and associated stellar flares play a significant role in habitability, either stifling life or catalyzing abiogenesis depending on the emission frequency, magnitude, and orientation. Clouds and vortices may be the source of spectral and photometric variability observed at the L/T transition of BDs and are expected in gas giant exoplanets. We develop a versatile analytical framework to model and infer surface inhomogeneities that can be applied to both spectroscopic and photometric data. This model is validated against a slew of numerical simulations. Using archival spectroscopic and photometric data, we infer starspot parameters (location, size, and contrast) and generate global surface maps for Luhman 16B (an early T dwarf and one of our solar system’s nearest neighbors at a distance of ≈2 pc). We confirm previous findings that Luhman 16B’s atmosphere is inhomogeneous with time-varying features. In addition, we provide tentative evidence of longer timescale atmospheric structures such as dark equatorial and bright midlatitude to polar spots. These findings are discussed in the context of atmospheric circulation and dynamics for ultracool dwarfs. Our analytical model will be valuable in assessing the feasibility of using ELTs to study surface inhomogeneities of gas giant exoplanets and other ultracool objects.