H-alpha and Ca ii Infrared Triplet Variations During a Transit of the 23 Myr Planet V1298 Tau c
H-alpha and Ca ii Infrared Triplet Variations During a Transit of the 23 Myr Planet V1298 Tau c
复制标题
DOI：
10.3847/1538-3881/ac1f24
复制
发表时间：
2021-07
期刊：
影响因子：
--
通讯作者：
A. D. Feinstein;B. Montet;Marshall C. Johnson;J. Bean;T. David;M. Gully-Santiago;J. Livingston;R. Luger
中科院分区：
文献类型：
--
作者：
A. D. Feinstein;B. Montet;Marshall C. Johnson;J. Bean;T. David;M. Gully-Santiago;J. Livingston;R. Luger
年轻的凌日系外行星(<；100Myr)通过光蒸发提供了对大气演化的重要洞察。然而，由于年轻恒星的活动和显著的星盘不均匀，用透射谱测量来确定大气成分和质量损失是具有挑战性的。我们观测到了V1298Tau c的完全凌日，它是一颗23 Myr，5.59 R的⊕行星，优雅地绕着一颗年轻的K0-K1.5太阳类似物运行在双子座北。我们用CaII红外三线组测量了V1298Tau-c的多普勒层析信号，得到了λ=5°±15°的投影倾角。断层扫描信号只出现在Ca II IRT的色球驱动核心，这可能是恒星-行星相互作用的结果。此外，我们还发现H-α谱线的过量吸收在渡越过程中平稳地减少。虽然这可能是初步探测到热气体逃离行星，但我们发现，这种变化与对其他年轻恒星的类似时间尺度的观测是一致的，这些恒星没有在类似的时间尺度上凌日行星。我们发现，这种变化也可以用周围有光斑的恒星黑子的存在来解释。需要在V1298Tau c凌日内外进行更多的观测，以确定Ca II IRT和Hα线变化的性质。
Young transiting exoplanets (<100 Myr) provide crucial insight into atmospheric evolution via photoevaporation. However, transmission spectroscopy measurements to determine atmospheric composition and mass loss are challenging due to the activity and prominent stellar disk inhomogeneities present on young stars. We observed a full transit of V1298 Tau c, a 23 Myr, 5.59 R ⊕ planet orbiting a young K0-K1.5 solar analog with GRACES on Gemini North. We were able to measure the Doppler tomographic signal of V1298 Tau c using the Ca ii infrared triplet (IRT) and find a projected obliquity of λ = 5° ± 15°. The tomographic signal is only seen in the chromospherically driven core of the Ca ii IRT, which may be the result of star-planet interactions. Additionally, we find that excess absorption of the Hα line decreases smoothly during the transit. While this could be a tentative detection of hot gas escaping the planet, we find this variation is consistent with similar timescale observations of other young stars that lack transiting planets over similar timescales. We show this variation can also be explained by the presence of starspots with surrounding facular regions. More observations both in and out of the transits of V1298 Tau c are required to determine the nature of the Ca ii IRT and Hα line variations.