النجم المرافق يخفي توأماً خفياً سريع

الملخص الأصلي

كما كتبه المؤلفون، بالإنجليزية arXiv:2604.03767

We present the discovery of a low-mass companion located at $$\rho$$ $$\sim$$ 0\farcs{}85 ($$r_{\rm proj} \approx 62~au$$) from the early-type 1.2 Gyr-old star HIP 53005 using direct imaging data from the Subaru and Keck Telescopes and astrometry from the Hipparcos-Gaia Catalog of Accelerations. The companion, HIP 53005 C, is a component of a multiple system also including a $$\approx$$ 12\farcs{}4-separation M dwarf companion inducing a negligible proper motion acceleration. HIP~53005 C's position on color-magnitude diagrams, the fit of its spectral energy distribution to atmosphere models, and its location on an empirical mass-magnitude diagram all suggest that it lies at the M/L transition and near the hydrogen-burning limit ($$\sim80~M_{\rm Jup}$$). However, our orbital fitting combining direct-imaging relative astrometry with proper motion acceleration favors a much higher dynamical mass of $$\sim185\ M_{\rm Jup}$$. An additional unseen, more closely-orbiting companion below the detection limit (at $$\rho\lesssim0\farcs2$$)) may explain this discrepancy. Alternatively, HIP~53005C could be a low-mass binary like Gliese~229Bab, making this system an intriguing laboratory for studying multiple star formation.