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arXiv 2409.07552astro-ph.EP
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JWST COMPASS:超级地球L 98-59 c的3-5微米透射光谱

JWST COMPASS: The 3-5 Micron Transmission Spectrum of the Super-Earth L 98-59 c

Nicholas Scarsdale, Nicholas Wogan, Hannah R. Wakeford, Nicole L. Wallack, Natasha E. Batalha, Lili Alderson, Artyom Aguichine, Angie Wolfgang, Johanna Teske, S… 展开作者

Nicholas Scarsdale, Nicholas Wogan, Hannah R. Wakeford, Nicole L. Wallack, Natasha E. Batalha, Lili Alderson, Artyom Aguichine, Angie Wolfgang, Johanna Teske, Sarah E. Moran, Mercedes Lopez-Morales, James Kirk, Tyler Gordon, Peter Gao, Natalie M. Batalha, Munazza K. Alam, Jea Adams Redai

AI总结:

本研究利用JWST NIRSpec观测超级地球L 98-59 c的3-5微米透射光谱,发现其光谱无特征,排除了原始氢氦、低金属丰度及纯甲烷大气,为小半径行星缺乏延展大气提供了新证据。

摘要:

我们公布了系外超级地球L 98-59 c的JWST NIRSpec透射光谱。这颗体积较小(行星半径Rₚ=1.385±0.085倍地球半径R⊕,行星质量Mₚ=2.22±0.26倍地球质量M⊕)的温暖行星(平衡温度T_eq=553K),位于一颗近邻明亮(J星等=7.933)M3V型恒星的多行星系统中。我们发现,在现有数据精度下,L 98-59 c的透射光谱无特征。我们在分辨率R~200(30像素宽 bin)下,NIRSpec G395H的NRS1探测器精度达22ppm,NRS2探测器精度达36ppm。在该精度下,我们可排除云压层最高至少约0.1毫巴范围内的原始氢-氦大气。通过与大气正演模型对比,我们还在3σ置信水平下排除了大气金属丰度低于约300倍太阳值的情况(等效于大气平均分子量低于约10克/摩尔),同时排除了纯甲烷大气。与数据兼容的剩余情形包括:行星完全无大气,或存在更高平均分子量的大气,如富二氧化碳或富水大气。本研究为“半径≲1.5倍地球半径的行星缺乏延展大气”这一观点补充了更多证据。

英文摘要:

We present a JWST NIRSpec transmission spectrum of the super-Earth exoplanet L 98-59 c. This small (R$_p=1.385\pm0.085$R$_\oplus$, M$_p=2.22\pm0.26$R$_\oplus$), warm (T$_\textrm{eq}=553$K) planet resides in a multi-planet system around a nearby, bright (J = 7.933) M3V star. We find that the transmission spectrum of L 98-59 c is featureless at the precision of our data. We achieve precisions of 22ppm in NIRSpec G395H's NRS1 detector and 36ppm in the NRS2 detector at a resolution R$\sim$200 (30 pixel wide bins). At this level of precision, we are able rule out primordial H$_2$-He atmospheres across a range of cloud pressure levels up to at least $\sim$0.1mbar. By comparison to atmospheric forward models, we also rule out atmospheric metallicities below $\sim$300$\times$ solar at 3$σ$ (or equivalently, atmospheric mean molecular weights below $\sim$10~g/mol). We also rule out pure methane atmospheres. The remaining scenarios that are compatible with our data include a planet with no atmosphere at all, or higher mean-molecular weight atmospheres, such as CO$_2$- or H$_2$O-rich atmospheres. This study adds to a growing body of evidence suggesting that planets $\lesssim1.5$R$_\oplus$ lack extended atmospheres.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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