近距岩质系外行星的气候与可观测性的广泛探索：应用于Ross 128 b
A broad exploration of climate and observability of close-in rocky exoplanets: applications to Ross 128 b
中文总结 AI 辅助
本研究以Ross 128 b为原型，通过3D气候模型与Pytmosph3R光谱模拟，细化近距岩质系外行星反射率预测，发现其低反射率特征，强调需用准确气候模型优化下一代光谱仪准备。
中文摘要 AI 辅助
VLT/RISTRETTO、ELT/ANDES和ELT/PCS不久将结合高对比度成像与反射光高分辨率光谱，实现对M型矮星周围宜居带内缘更近轨道上的非凌星小型岩质系外行星的大气表征。反射光可观测性的关键参数是与波长相关的反射率，由气候、表面和大气特性决定。本研究细化了该类天体的光谱反射率预测，以Ross 128 b为原型，在RISTRETTO和ANDES光谱范围内，针对不同大气场景提供物理自洽的几何反照率估计。我们对Ross 128 b开展3D全球气候模型模拟，探究不同大气成分、表面气压、水储量和自旋-轨道共振下的可能气候 regime，随后用Pytmosph3R计算合成反射光谱，评估各场景的光谱特征，并讨论探测能力及约束气候的仪器性能。结果显示，接受与Ross 128 b相当辐照的无云岩质行星，在所有场景中，RISTRETTO波段的几何反照率为0.07-0.2，ANDES波段为0-0.14，反射率较低；该低反射率可源于昼侧无云或表面冰沉积，或因高水汽浓度导致的强大气吸收，具体取决于参数配置。这些特征是此前研究中近距、低水储量行星的气候湿双稳态的典型表现。我们的结果表明，任意反照率假设（如常用的类地行星0.3值）会高估该类天体的反射率，凸显了准确气候模型对改进反射率预测及优化下一代光谱仪准备工作的必要性。
英文摘要
VLT/RISTRETTO, ELT/ANDES and ELT/PCS will soon enable atmospheric characterization of non-transiting, small rocky exoplanets orbiting closer than the inner edge of the Habitable Zone around M dwarfs, combining high-contrast imaging with high-resolution spectroscopy in reflected light. A key parameter for reflected-light observability is wavelength-dependent reflectivity, shaped by climate, surface and atmospheric properties. This work refines spectral reflectivity predictions for this population. Using Ross 128 b as a prototype, we provide physically consistent geometric albedo estimates within the RISTRETTO and ANDES spectral ranges across diverse atmospheric scenarios. We run 3D global climate model simulations of Ross 128 b for varying atmospheric compositions, surface pressures, water inventories and spin-orbit resonances to explore its possible climate regimes. We then compute synthetic reflectance spectra with Pytmosph3R to assess spectral signatures per scenario and discuss detectability and instrument capacity for constraining climate. Results show hazeless rocky planets receiving irradiation similar to Ross 128 b exhibit low reflectivity, with geometric albedos of 0.07-0.2 in the RISTRETTO bandpass and 0-0.14 in the ANDES bandpass across all scenarios. This low reflectivity can stem from the lack of clouds or surface ice deposits on the dayside, or from strong atmospheric absorption due to high water vapor concentrations, depending on the parameter configurations. These features are characteristic of the climate moist bistability found in close-in, low-water-reservoir planets in previous studies. Our results suggest arbitrary albedo assumptions, such as the common 0.3 Earth-like value, can overestimate reflectivity for this population, highlighting the need for accurate climate models to improve reflectivity predictions and optimize preparation for next-generation spectrographs.
