AF Lep b：结合天体测量与直接成像数据探测到的最低质量行星
AF Lep b: the lowest mass planet detected coupling astrometric and direct imaging data
AI总结：
本文结合直接成像与天体测量本动异常信号，在AF Lep周围发现质量仅2-5 MJup的伴星AF Lep b，首次实现远低于氘燃烧极限的伴星探测，并通过轨道拟合验证其质量与轨道参数。
摘要：
研究目的：我们利用直接成像技术在恒星AF Lep周围搜寻低质量伴星，该恒星通过比较Hipparcos和Gaia eDR3星表获得了显著的本动异常（PMa）信号。方法：我们使用VLT/SPHERE的IFS和IRDIS子系统在近红外（NIR）波段对AF Lep进行了两个历元的观测，覆盖从Y到K光谱波段（0.95至2.3 μm之间）的波长范围。随后使用高对比度成像技术——角差分成像（ADI）和光谱差分成像（SDI）对数据进行处理，以提取恒星低质量伴星的信号。结果：在第一历元中，在距恒星约0.335角秒处、位置角约70.5度处探测到一个暗弱伴星，第二历元中位置相似。这对应于约9个天文单位的投影间距。提取的光度数据使我们能够估计该伴星的质量在2至5 MJup之间。该质量与利用天体测量数据推导出的伴星动力学质量（5.2-5.5 MJup）高度吻合。这是首次将直接成像与PMa测量相结合发现的、质量远低于氘燃烧极限的伴星。使用orvara工具进行的轨道拟合进一步证实了伴星质量，并确定了其主要轨道参数。
英文摘要：
Aims. Using the direct imaging technique we searched for low mass companions around the star AF Lep that presents a significant proper motion anomaly (PMa) signal obtained from the comparison of Hipparcos and Gaia eDR3 catalogs. Methods. We observed AF Lep in two epochs with VLT/SPHERE using its subsystems IFS and IRDIS in the near-infrared (NIR) covering wavelengths ranging from the Y to the K spectral bands (between 0.95 and 2.3 μm). The data were then reduced using the high-contrast imaging techniques angular differential imaging (ADI) and spectral differential imaging (SDI) to be able to retrieve the signal from low mass companions of the star. Results. A faint companion was retrieved at a separation of ~0.335" from the star and with a position angle of ~70.5 deg in the first epoch and with a similar position in the second epoch. This corresponds to a projected separation of ~9 au. The extracted photometry allowed us to estimate for the companion a mass between 2 and 5 MJup. This mass is in good agreement with what is expected for the dynamic mass of the companion deduced using astrometric measures (5.2-5.5 MJup). This is the first companion with a mass well below the deuterium burning limit discovered coupling direct imaging with PMa measures. Orbit fitting done using the orvara tool allowed to further confirm the companion mass and to define its main orbital parameters.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
