A comprehensive infrared spectroscopic study of star TRAPPIST-1 is a crucial step toward the detailed examination of its planets. While the presence of Earth’s atmosphere has limited the spectral extent of such a study up to now, the Near Infrared Imager and Slitless Spectrograph (NIRISS) and the Near Infrared Spectrograph instruments aboard the James Webb Space Telescope (JWST) can now yield the 0.6–5 μm spectral energy distribution (SED) of the star. Here we translate TRAPPIST-1's SED into tight constraints on its luminosity (L _bol = 0.000566 ± 0.000022 L _⊙), effective temperature (T _eff = 2569 ± 28 K), and metallicity ([Fe/H] = 0.052 ± 0.073) and investigate the behavior of its gravity-sensitive indices. Through band-by-band comparisons of the NIRISS and ground-based spectra, TRAPPIST-1 exhibits a blend of both field source and intermediate-gravity spectral characteristics, suggesting that the star is likely a field-age source with spectral features reminiscent of young objects. We also employ photospheric modeling incorporating theoretical and JWST spectra to constrain stellar surface heterogeneities, finding that the limited fidelity of current stellar spectral models precludes definitive constraints on the physical parameters of the distinct spectral components giving rise to TRAPPIST-1's photospheric heterogeneity and variability. In addition, we find intermodel differences in the inferences of properties (e.g., the effective temperature) over one order of magnitude larger than the instrument-driven uncertainties (∼100 K vs. ∼4 K), pointing toward a model-driven accuracy wall. Our findings call for a new generation of stellar models to support the optimal mining of JWST data and further constraining stellar—and ultimately planetary—properties.

中文翻译：

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更新了超冷矮星 TRAPPIST-1 的光谱特征


对 TRAPPIST-1 恒星进行全面的红外光谱研究是详细检查其行星的关键一步。虽然到目前为止，地球大气层的存在限制了此类研究的光谱范围，但近红外成像仪和无缝摄谱仪 (NIRISS) 以及詹姆斯·韦伯太空望远镜 (JWST) 上的近红外摄谱仪仪器现在可以产生 0.6– 5 μ m 恒星的光谱能量分布（SED）。在这里，我们将 TRAPPIST-1 的 SED 转化为对其光度的严格约束（ L_玻尔= 0.000566 ± 0.000022 L _⊙ ), 有效温度(时间_eff = 2569 ± 28 K）和金属丰度（[Fe/H] = 0.052 ± 0.073）并研究其重力敏感指数的行为。通过对 NIRISS 和地面光谱的逐波段比较，TRAPPIST-1 表现出场源和中重力光谱特征的混合，表明这颗恒星很可能是场年龄源，其光谱特征让人想起年轻时的恒星。对象。我们还采用结合理论和 JWST 光谱的光球模型来约束恒星表面异质性，发现当前恒星光谱模型的有限保真度排除了对不同光谱成分的物理参数的明确限制，从而导致了 TRAPPIST-1 的光球异质性和变异性。此外，我们发现属性推论（例如有效温度）的模型间差异比仪器驱动的不确定性（∼100 K vs. ∼4 K）大一个数量级，这表明模型驱动的精度墙。 我们的研究结果需要新一代的恒星模型来支持 JWST 数据的优化挖掘，并进一步限制恒星（最终是行星）的特性。