AI 中文总结
该研究利用多时期WISE成像的自行，通过贝叶斯MCMC分析，研究附近主序星宽次恒星伴星群体，得出伴星质量和半长轴分布的幂律指数及发生率，样本更具稳健性，支持宽次恒星伴星是恒星双星低质量延伸的观点。
AI 中文摘要
背景。宽次恒星伴星为研究褐矮星和巨行星的形成与演化提供了重要基准。它们与恒星主星的关联也提供了孤立天体难以获得的年龄和金属丰度限制。目的。我们使用多时期WISE成像得出的自行来研究附近主序星的宽次恒星伴星群体。我们的样本包括20秒差距内的2103颗恒星，对距离达20000天文单位、温度低至约300K的伴星敏感。方法。我们使用贝叶斯马尔可夫链蒙特卡罗（MCMC）分析来约束伴星质量和半长轴分布，同时考虑观测选择效应，包括暗伴星可探测性降低。我们假设幂律分布，\(d^2n \propto M^\alpha a^\beta dM da\)。结果。我们得出\(\alpha=-0.21^{+0.31}_{-0.27}\)，\(\beta=-1.38\pm0.32\)，对于质量为5 - 80\(M_J\)、距离为1000 - 20000天文单位的伴星，发生率为\(1.07^{+0.31}_{-0.24}\%\)。发生率随距离减小和主星质量增加而增加。结论。尽管目标选择不同，但推断的伴星质量分布与先前的直接成像调查一致。质量和距离的幂律分布也与恒星双星一致。我们的样本比先前成像调查大约一个数量级，提供了迄今为止最稳健的宽次恒星伴星统计特征。这些结果支持宽次恒星伴星代表恒星双星群体的低质量延伸而非近距离巨行星直接延伸的解释。
英文摘要
Context. Wide substellar companions provide important benchmarks for studying the formation and evolution of brown dwarfs and giant planets. Their association with stellar primaries also provides age and metallicity constraints that are difficult to obtain for isolated objects. Aims. We investigate the population of wide substellar companions to nearby main-sequence stars using proper motions derived from multi-epoch WISE imaging. Our sample includes 2103 stars within 20 pc and is sensitive to companions down to $\sim300$ K at separations up to 20,000 AU. Methods. We use a Bayesian Markov Chain Monte Carlo (MCMC) analysis to constrain the companion mass and semi-major axis distributions while accounting for observational selection effects, including the reduced detectability of faint companions. We assume power-law distributions, $d^2n \propto M^αa^βdM da$. Results. We derive $α=-0.21^{+0.31}_{-0.27}$, $β=-1.38\pm0.32$, and an occurrence rate of $1.07^{+0.31}_{-0.24}\%$ for companions with masses of 5--80 $M_J$ at separations of 1,000--20,000 AU. The occurrence rate increases towards smaller separations and for more massive host stars. Conclusions. The inferred companion mass distribution is consistent with previous direct imaging surveys despite differences in target selection. The power-law distributions in both mass and separation also agree with those of stellar binaries. Our sample is about an order of magnitude larger than those of previous imaging surveys, providing the most robust statistical characterisation of wide substellar companions to date. These results support the interpretation that wide substellar companions represent the low-mass extension of the stellar binary population rather than a direct extension of close-in giant planets.
