AI 中文总结
该研究通过结合多卫星数据与光谱数据，搜寻到可能起源于河外的行星候选体宿主，经审查确认两个最具合理性的候选系统，若证实将表明行星系统可在矮星系形成并留存至银河系。
AI 中文摘要
迄今为止，所有已知的系外行星系统都被发现位于当前银河系内的恒星周围，而形成于外部星系的行星仍在很大程度上未被探索。这类系统将为研究银河系以外星系环境中的行星形成提供独特的探针。我们结合文献汇编的Kepler、K2和TESS行星候选体宿主星样本，以及Gaia DR3天体测量与视向速度数据，还纳入了LAMOST DR9 DD-Payne星表中的金属丰度与[Mg/Fe]丰度，以搜寻候选的并合晕行星宿主。我们识别出11个具有晕状运动学特征的行星候选体宿主，其中5个拥有可靠的化学丰度测量值。在这些宿主中，有4个系统呈现出低金属丰度（[Fe/H]<-0.7）和低[Mg/Fe]比值，与标准的银河系厚盘序列不符，表明其具有并合矮星系的特征性增丰历史。我们进一步利用Gaia RUWE、Gaia DR3邻近天体检查、凌星深度奇偶比较、次食搜寻、独立BLS周期恢复，以及与ExoFOP及现有后续观测信息的比对，开展了统一的假阳性评估。该审查确认EPIC~211407755和TIC~239541449为最具合理性但仍未被验证的行星候选体系统；TIC~293432942更可能与混源或其他双星相关的假阳性有关；而TIC~184739529仍是高风险的巨伴星候选体，其行星属性尚不明确。若得到证实，EPIC~211407755和TIC~239541449将表明行星系统可以在矮星系环境中形成，并在后续并合入银河系的过程中得以留存。
英文摘要
To date, all known exoplanetary systems have been identified around stars currently residing in the Milky Way, whereas planets formed in external galaxies remain largely unexplored. Such systems would offer a unique probe of planet formation in galactic environments distinct from the Milky Way. We combine a literature-compiled sample of Kepler, K2, and TESS planet-candidate host stars with Gaia DR3 astrometry and radial velocities, and incorporate metallicities and [Mg/Fe] abundances from the LAMOST DR9 DD-Payne catalogue, to search for candidate accreted-halo planet hosts. We identify 11 planet-candidate hosts with halo-like kinematics, five of which have reliable chemical abundance measurements. Among these, four systems exhibit low metallicities ([Fe/H]<-0.7) and low [Mg/Fe] ratios that are inconsistent with the canonical Milky Way thick-disc sequence, indicative of enrichment histories characteristic of accreted dwarf galaxies. We further carry out a uniform false-positive assessment using Gaia RUWE, Gaia DR3 neighbourhood checks, odd--even transit-depth comparisons, secondary-eclipse searches, independent BLS period recovery, and comparison with ExoFOP and available follow-up information. This vetting identifies EPIC~211407755 and TIC~239541449 as the most plausible, although still unvalidated, planet-candidate systems. TIC~293432942 is more likely associated with a blended or otherwise binary-related false positive, whereas TIC~184739529 remains a high-risk giant-companion candidate whose planetary nature is uncertain. If confirmed, EPIC~211407755 and TIC~239541449 would suggest that planetary systems can form in dwarf-galaxy environments and subsequently survive accretion into the Milky Way.
Comments11 pages, 5 figures, accepted for publication in MNRAS
