发表机构
Columbia University（哥伦比亚大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用JWST的12次凌星观测对LP 890-9c周围的系外卫星进行搜寻，以95%置信度排除了半径小至0.1倍地球半径的系外卫星，证实JWST可探测极小系外卫星，为后续观测提供了支撑。
AI 中文摘要
迄今为止，即便使用詹姆斯·韦布空间望远镜（JWST），也无法探测到小至月球大小的系外卫星；目前仅开展了两项使用JWST对束缚态行星周围系外卫星的搜寻工作，均依赖单次JWST凌星观测。我们认为，目前低于预期的灵敏度部分源于行星+卫星凌星模型在面对单次事件时存在的显著内在灵活性，以及意外的系统噪声。为验证这一点，我们使用12次JWST凌星观测对岩质温带带系外行星LP 890-9c开展搜寻，未发现系外卫星存在的证据，但在整个希尔球区域以95%置信度排除了半径为0.1倍地球半径（$0.1R_{\bigoplus}$）的系外卫星，这是迄今为止灵敏度最高的搜寻工作。我们的限制条件排除了许多真实太阳系卫星的类似天体，如木卫二（Europa）、土卫五（Rhea）和天卫一（Umbriel）。不过，我们强调LP 890-9c的近距轨道（0.04天文单位）会导致任何大于约0.1倍地球半径的卫星因潮汐作用难以存活数十亿年。无论如何，我们的研究明确证实JWST确实可以探测到极小的卫星；此外，我们发现即便单次凌星也能给出可观的限制，仅存在一个受红噪声污染的历例外，但若将其与一个更干净的历星配对，灵敏度可恢复至与其他任何配对无差异的水平，这对后续使用JWST观测开普勒-167e（Kepler-167e）的第二次凌星具有积极意义。
英文摘要
To date, even with JWST, it has not been possible to test for exomoons as small as the Moon. Only two reported searches for exomoons around bound planets have been attempted with JWST, both of which relied on a single JWST transit. We suggest that the below expectation sensitivity to date is, in part, a product of the considerable intrinsic flexibility of the planet+moon transit model when confronted with a single event, and the presence of unanticipated systematic noise. To test this, we present a search around the rocky, temperate-zone exoplanet LP 890-9c using twelve JWST transits. We find no evidence for an exomoon but exclude $0.1R_{\oplus}$ moons to 95% confidence across the entire Hill region, representing by far the most sensitive search to date. Our limits exclude analogs to many real Solar System moons, such as Europa, Rhea and Umbriel. However, we emphasize that the close-in orbit of LP 890-9c (0.04au) would make any moons larger than ${\sim}0.1R_{\oplus}$ unlikely to survive for many Gyr due to tides. Regardless, our study firmly establishes that JWST can indeed probe down to remarkably small moons. Further, we find that even a single transit can deliver impressive limits, with the exception of one epoch that is contaminated by red noise. However, by pairing it with just one cleaner epoch, the sensitivity recovers to a level indistinguishable from any other pairing, which bodes well for a potential second JWST transit of Kepler-167e.
CommentsAccepted in AJ
