论文标题
表征与JWST的云彩温带迷你纽扣的气氛
Characterising Atmospheres of Cloudy Temperate Mini-Neptunes with JWST
论文作者
论文摘要
即将到来的詹姆斯·韦伯（James Webb）太空望远镜（JWST）有望使用过境光谱法进行温带微型纳入大气的研究。但是，高空云可能会通过静音特征来阻碍其大气表征。在这项研究中，我们系统地研究了JWST仪器配置，以表征多云的迷你新闻大气，评估仪器选择和波长覆盖范围的重要性，重点是Niriss和NirSpec。我们考虑在附近的M矮人K2-18 B和TOI-732 C附近绕着旋转的两个温带迷你北极，平衡温度低于400 K，作为案例研究和使用不同仪器配置的观察结果，每件仪器每仪器一次运输一次。我们发现，他们具有适度观察时间和足够的波长覆盖率的JWST传输光谱也可以提供关键分子H2O，CH4和NH3的精确限制，即使在存在明显高的高度云的情况下也能提供。最好的约束是通过将所有三个高分辨率NIRSPEC光栅（G140H+G235H+G395H）组合在一起来获得的，它们涵盖了〜1-5 $μ$ m范围。使用这种三仪构型配置的单次传输观察可以分别对低至3 MBAR的云顶压和K2-18 B和TOI-732 C的0.1 MBAR的精确限制，假定标称的10x太阳能金属性。约束因仪器组合而异。我们发现NIRSPEC G235H+G395H是最佳的两种仪器配置，而NIRISS或NIRSPEC G235H对于单仪器观测是最佳的。没有高海拔云，即使是单仪器的观测值也可以为这些行星提供良好的丰富限制。我们的发现强调了JWST传播光谱法对附近M矮人绕的温带迷你新猎人表征的希望。
The upcoming James Webb Space Telescope (JWST) promises a generational shift in the study of temperate mini-Neptune atmospheres using transit spectroscopy. High-altitude clouds however threaten to impede their atmospheric characterisation by muting spectral features. In this study, we systematically investigate JWST instrument configurations for characterising cloudy mini-Neptune atmospheres, assessing the importance of instrument choice and wavelength coverage, focusing on NIRISS and NIRSpec. We consider two temperate mini-Neptunes orbiting nearby M dwarfs, K2-18 b and TOI-732 c, with equilibrium temperatures below 400 K, as case studies and assess observations using different instrument configurations with one transit per instrument. We find that their JWST transmission spectra with modest observing time and adequate wavelength coverage can provide precise abundance constraints of key molecules H2O, CH4, and NH3 even in the presence of clouds at significantly high altitudes. The best constraints are obtained by combining all three high-resolution NIRSpec gratings (G140H+G235H+G395H) that together span the ~1-5 $μ$m range. Single-transit observations with this three-instrument configuration allow precise abundance constraints for cloud-top pressures as low as 3 mbar and 0.1 mbar for K2-18 b and TOI-732 c, respectively, assuming a nominal 10x solar metallicity. The constraints vary with instrument combinations. We find that NIRSpec G235H+G395H is the optimal two-instrument configuration, while NIRISS or NIRSpec G235H is optimal for single-instrument observations. Absent high-altitude clouds, even single-instrument observations can provide good abundance constraints for these planets. Our findings underscore the promise of JWST transmission spectroscopy for characterising temperate mini-Neptunes orbiting nearby M dwarfs.
