AI 中文总结
研究人马座9号在2013 - 2014年近日点通过期间的射电辐射，通过监测获取多波段数据。分析射电数据发现其近日点附近射电辐射特征与其他O型双星不同，标准磁场模型无法解释，需改进模型，未来观测可进一步约束模型。
AI 中文摘要
大质量恒星双星中的碰撞风会产生非热射电辐射和增强的X射线辐射。我们研究了非热辐射源人马座9号，它是一个长周期且高度偏心的双星。我们在其2013 - 2014年近日点通过期间对人马座9号进行了监测，获取了射电、X射线和光学光谱数据。本文分析了射电数据。3.6厘米、6厘米和20厘米处的射电数据在近日点附近显示出最大值。其他O型双星中的非热射电辐射源在近日点附近通量最小，因为同步辐射被两恒星风的自由 - 自由吸收所吸收。人马座9号并非如此，因为即使在近日点，轨道间距也足以维持风 - 风碰撞及其相关的同步辐射在两恒星有效自由 - 自由半径之外。我们用与离恒星距离成反比（1/r）减小的局部磁场进行的标准建模无法解释观测到的通量。相反，我们需要采用比1/r下降更快的局部磁场。虽然我们的模型对数据拟合得尚可，但仍有改进空间。更先进的建模应包括磁流体动力学以及相对论电子注入、加速和冷却的更详细物理。在远离近日点的轨道相位进行射电观测可对模型施加进一步限制。
英文摘要
Colliding winds in massive-star binaries generate non-thermal radio emission and an increased X-ray emission. We study the radio emission of the non-thermal emitter 9 Sgr, which is a long-period and highly eccentric binary. We conducted a monitoring campaign of 9 Sgr around its 2013 - 2014 periastron passage, obtaining radio, X-ray and optical spectroscopy data. In this paper, we analyse the radio data. The radio data at 3.6, 6 and 20 cm show a maximum near periastron. Other non-thermal radio emitters among O-type binaries have a minimum flux near periastron, because the synchrotron emission is absorbed by the free-free absorption in the two stellar winds. This is not the case for 9 Sgr, because even at periastron the orbital separation is sufficient to maintain the wind-wind collision and its associated synchrotron emission outside the effective free-free radius of both stars. Our standard modelling with a local magnetic field that decreases inversely proportional to the distance from the stars (1/r) fails to explain the observed fluxes. Instead, we need to adopt a local magnetic field that decreases faster than 1/r. While our model provides an acceptably good fit to the data, there is clearly still room for improvement. More advanced modelling should include magnetohydrodynamics and more detailed physics of the injection, acceleration and cooling of the relativistic electrons. Radio observations at orbital phases away from periastron can put further constraints on the models.
Comments8 pages, 4 figures, language-edited version, accepted for publication in A&A
