084503

With a total mass of over 100Msun comma e>0.9 and P_orbvirgul120yr comma HD93129A is one of the most extreme massive binaries known. Astrometric measurements of its orbit have revealed a periastron passage in Fall 2018. The strong stellar winds of the two stars and the tight separation at periastron are producing an intense wind-wind collision openParWWCclosePar and an unusually high thermal and non-thermal X-ray emission that we are currently monitoring. Here we request two additional 25ksec XMM observations to follow the X-ray emission decrease as the system progresses away from periastron. Obtaining a full coverage of the X-ray emission of HD93129A is a once-in-a-life-time opportunity to achieve observational breakthroughs in our understanding of the shock physics and of the WWC hydrodynamics.

HD 93129A是目前已知的最极端大质量双星系统之一，其总质量超过100倍太阳质量，偏心率e>0.9，轨道周期约120年。对其轨道开展的天体测量显示，该系统曾在2018年秋季发生近心点通过事件。两颗恒星的强星风与近心点处的极近距离共同引发了剧烈的星风碰撞（wind-wind collision, WWC），并产生了异常强烈的热与非热X射线辐射，我们目前正对此进行监测。在此我们申请追加两次时长为25千秒的XMM观测，以追踪该系统远离近心点过程中X射线辐射的衰减过程。完整获取HD 93129A的X射线辐射全覆盖数据，是一次千载难逢的观测契机，有望在我们理解激波物理与星风碰撞流体动力学的研究中取得突破性进展。