刻画热海王星沙漠中的世界：LTT 9779 b 的 HST WFC3 凌星观测
Characterising a World Within the Hot Neptune Desert: Transit Observations of LTT 9779 b with HST WFC3
AI总结：
该研究分析热海王星沙漠行星 LTT 9779 b 的 HST 透射光谱，探测到水、二氧化碳和氢化铁特征，未发现氦逃逸迹象，并精化了轨道参数。
摘要：
我们对 LTT 9779 b 进行了大气分析，这是一颗位于热海王星沙漠中的罕见行星，已使用 HST WFC3 G102 和 G141 进行了观测。覆盖 0.8–1.6 μm 的联合透射光谱显示，凌星深度随波长逐渐增加。我们首选的模型显示存在 H₂O、CO₂ 和 FeH 的证据，显著性分别为 3.1σ、2.4σ 和 2.1σ。为了限制该行星的大气逃逸速率，我们在 G102 数据中搜寻 1.083 μm 的氦线，但未发现表明存在逃逸大气的过量吸收证据。我们利用 HST 数据和 TESS 的观测改进了 LTT 9779 b 的轨道星历，并搜寻了轨道衰减或拱线进动的证据，但未发现。使用 JWST NIRISS 对 LTT 9779 b 的相位曲线观测将提供对该行星大气的更深入认识，而预期的大气逃逸可能通过针对其他示踪物（如 Lyman α）的进一步观测而被探测到。
英文摘要：
We present an atmospheric analysis of LTT 9779 b, a rare planet situated in the hot Neptune desert, that has been observed with HST WFC3 G102 and G141. The combined transmission spectrum, which covers 0.8 - 1.6 $μ$m, shows a gradual increase in transit depth with wavelength. Our preferred atmospheric model shows evidence for H$_{\rm 2}$O, CO$_{\rm 2}$ and FeH with a significance of 3.1 $σ$, 2.4 $σ$ and 2.1 $σ$, respectively. In an attempt to constrain the rate of atmospheric escape for this planet, we search for the 1.083 $μ$m Helium line in the G102 data but find no evidence of excess absorption that would indicate an escaping atmosphere using this tracer. We refine the orbital ephemerides of LTT 9779 b using our HST data and observations from TESS, searching for evidence of orbital decay or apsidal precession, which is not found. The phase-curve observation of LTT 9779 b with JWST NIRISS should provide deeper insights into the atmosphere of this planet and the expected atmospheric escape might be detected with further observations concentrated on other tracers such as Lyman $α$.
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。
