TESS搜寻年轻及成熟系外行星（THYME）XI：一颗围绕大熊座移动星群中400Myr附近类太阳宿主运行的地球大小行星
TESS Hunt for Young and Maturing Exoplanets (THYME) XI: An Earth-sized Planet Orbiting a Nearby, Solar-like Host in the 400Myr Ursa Major Moving Group
AI总结：
本文介绍了在年轻的大熊座移动星群中发现了一颗围绕类太阳恒星运行的地球大小系外行星HD 63433d，其半径为1.1地球半径，公转周期4.2天，是迄今已知年龄小于500 Myr的最小已确认系外行星且距离最近，为研究行星演化与大气逃逸提供了关键机会。
摘要：
年轻的类地世界是限制行星形成与演化主流理论的关键试验台。我们介绍了HD 63433d的发现——这是一颗近距离（22pc）、地球大小的行星，凌日一颗年轻的类太阳恒星（TOI-1726, HD 63433）。HD 63433d是在该多行星系统中探测到的第三颗行星。宿主恒星的运动学、自转和丰度属性表明它属于年轻的（414 $\pm$ 23 Myr）大熊座移动星群，我们使用来自Gaia DR3和TESS的新数据更新了其成员资格。我们对TESS光变曲线的凌日分析表明，HD 63433 d的半径为1.1 $R_\oplus$，以4.2天的周期近距离围绕其宿主恒星运行。迄今为止，HD 63433 d是年龄小于500 Myr的最小已确认系外行星，也是最近的年轻地球大小行星。此外，宿主恒星的视亮度（V $\approx$ 6.9 mag）使得这个凌日多行星系统有利于进一步研究，包括探测年轻地球大小世界大气流失的光谱后续观测。
英文摘要：
Young terrestrial worlds are critical test beds to constrain prevailing theories of planetary formation and evolution. We present the discovery of HD 63433d - a nearby (22pc), Earth-sized planet transiting a young sunlike star (TOI-1726, HD 63433). HD 63433d is the third planet detected in this multiplanet system. The kinematic, rotational, and abundance properties of the host star indicate that it belongs to the young (414 $\pm$ 23 Myr) Ursa Major moving group, whose membership we update using new data from Gaia DR3 and TESS. Our transit analysis of the TESS light curves indicates that HD 63433 d has a radius of 1.1 $R_\oplus$ and closely orbits its host star with a period of 4.2 days. To date, HD 63433 d is the smallest confirmed exoplanet with an age less than 500 Myr, and the nearest young Earth-sized planet. Furthermore, the apparent brightness of the stellar host (V $\approx$ 6.9 mag) makes this transiting multiplanet system favorable to further investigations, including spectroscopic follow-up to probe atmospheric loss in a young Earth-sized world.
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