利用Keck/NIRC2涡旋日冕仪搜寻嵌入原行星：确认Elias 2-24盘窄间隙中的核吸积行星
Searching for Embedded Protoplanets with the Keck/NIRC2 Vortex Coronagraph: Confirmation of a Core-accretion Planet in the Narrow Gap of the Elias 2-24 Disk
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中文总结 AI 辅助
利用Keck/NIRC2涡旋日冕仪对七颗恒星进行高对比度成像，确认了Elias 2-24盘窄间隙中的核吸积行星Elias 2-24 b，质量1.9-4.0木星质量，为最年轻外行星，对行星形成时间尺度有重要意义。
中文摘要 AI 辅助
我们展示了2018年5月至6月间利用Keck/NIRC2涡旋日冕仪在$L'$和$M_s$波段对七颗恒星进行的高对比度成像观测。所有目标都拥有带有间隙和空腔等子结构的原行星盘，这些结构可能标志着正在进行的行星形成过程。我们的目标是评估这些嵌入的行星能否被直接探测到。我们使用基于VIP Python包的自定义流程对观测数据进行了处理。通过角差分成像和参考差分成像结合主成分分析获得了后处理图像。最后，我们为所有目标导出了5$\sigma$对比度曲线和探测极限。我们确认了文献中先前提出的围绕Elias 2-24的行星候选体，其分离距离为394$\pm$31毫角秒（54.9$\pm$4.3天文单位），位置角为298.8$\pm$3.2度，位于原行星盘的窄间隙内。将测得的光度与1百万年等时线进行比较，在不考虑吸积效应的情况下，我们推断Elias 2-24 b的质量介于1.9至4.0倍木星质量之间，这与考虑间隙属性和行星-盘相互作用得出的估计一致。对于巡天中的所有系统，5$\sigma$探测极限在分离距离$\gtrsim$0.25角秒处达到1至11倍木星质量的灵敏度。由于Elias 2-24 b（年龄$\lesssim$1百万年）是迄今为止发现的最年轻的外行星，其确认对行星形成时间尺度和非常年轻盘中观测到的间隙起源具有重要意义。
英文摘要
We present high-contrast imaging observations of seven stars obtained with the Keck/NIRC2 vortex coronagraph between 2018 May and June in the $L'$ and $M_s$ bands. All targets host protoplanetary disks with substructures such as gaps and cavities, potentially tracing ongoing planet formation. Our aim is to assess whether these embedded planets can be directly detected. We reduced the observations with a custom pipeline based on the VIP Python package. Postprocessed images were obtained using angular differential imaging and reference differential imaging combined with principal component analysis. Finally, 5$σ$ contrast curves and detection limits were derived for all targets. We confirm the planetary candidate around Elias 2-24, previously proposed in the literature, at a separation of 394$\pm$31 mas (54.9$\pm4$.3 au) and a position angle of 298.8$\pm$3.2$^\circ$, within the narrow gap of the protoplanetary disk. Comparing the derived photometry with 1 Myr isochrones, we infer a mass between 1.9 and 4.0 Jupiter masses for Elias 2-24 b, without considering accretion effects, in agreement with estimates considering the properties of the gap and planet-disk interactions. For all the systems in the survey, the 5$σ$ detection limits reach sensitivities down to 1-11 Jupiter masses at separations $\gtrsim$0.25". Since Elias 2-24 b (age $\lesssim$1 Myr) is the youngest exoplanet discovered to date, its confirmation has important implications for planet formation timescales and the origin of the gaps observed in very young disks.
发表机构
- Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales（Diego Portales大学工程与科学学院天体物理研究所）
- Millennium Nucleus on Young Exoplanets and their Moons (YEMS)（年轻系外行星及其卫星千年核心）
- Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）
- Institute of Astronomy, KU Leuven（荷鲁芬大学天体物理研究所）
- STAR Institute, Université de Liège（列日大学STAR研究所）
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