W3 IRS5的毫米干涉测量：一个正在形成的梯形
Millimeter interferometry of W3 IRS5: A Trapezium in the making
摘要：
虽然大多数年轻的大质量恒星似乎是多重系统的一部分，但人们对这种多重性如何影响大质量恒星的形成知之甚少。高质量恒星形成区W3 IRS 5是一个年轻的大质量星团的最好例子，其中星团中心在厘米和红外波长下被分解为多个子源，这是一个潜在的原梯形系统。在AB位形下，用1.4mm和3.4mm处的PdBI对W3 IRS 5区进行了测图，观测到了激波跟踪的SiO和SO_2辐射。在连续谱中，我们检测到五个源，其中一个是首次检测到，而其余四个源的对应源是在近红外、中红外或无线电波长中检测到的。其中三个被探测到的源位于2100天文单位以内，假设是球对称的，这里的原恒星数密度超过了10^6颗原恒星pc^-3。下限的拱星质量的检测源进行了计算，虽然他们强烈影响的空间滤波的干涉仪。然而，在~750和~ 4700 AU之间的源的投影分离表明一个多个梯形系统。我们在SiO中检测到五个分子外流，其中两个几乎在视线方向，这使我们能够通过外流雕刻的空腔在NIR中看到坍缩的原恒星。SO_2的速度结构表明，一个旋转的，绑定系统，我们发现收敛流的引力湍流恒星形成和收敛流理论所预测的初步签名。所获得的数据强烈表明，集群环境对大质量恒星的形成有重大影响;然而，我们的数据并不能清楚地让我们区分正在进行的恒星形成过程是遵循整体崩溃还是竞争性吸积机制。
英文摘要：
Although most young massive stars appear to be part of multiple systems, it is poorly understood how this multiplicity influences the formation of massive stars. The high-mass star-forming region W3 IRS5 is a prime example of a young massive cluster where the cluster center is resolved into multiple subsources at cm and infrared wavelengths, a potential proto-Trapezium system. The region W3 IRS5 was mapped with the PdBI at 1.4mm and 3.4mm in the AB configurations, observing shock-tracing SiO and SO_2 emission. In the continuum we detect five sources, one of them for the first time, while counterparts were detected in the NIR, MIR or at radio wavelengths for the remaining four sources. Three of the detected sources are within the inner 2100AU, where the protostellar number density exceeds 10^6 protostars pc^-3 assuming spherical symmetry. Lower limits for the circumstellar masses of the detected sources were calculated, although they were strongly affected by the spatial filtering of the interferometer. However, the projected separations of the sources ranging between ~750 and ~4700AU indicate a multiple, Trapezium-like system. We detected five molecular outflows in SiO, two of them nearly in the line of sight direction, which allowed us to see the collapsing protostars in the NIR through the cavities carved by the outflows. The SO_2 velocity structure indicates a rotating, bound system, and we find tentative signatures of converging flows as predicted by the gravoturbulent star formation and converging flow theories. The obtained data strongly indicate that the clustered environment has a major influence on the formation of high-mass stars; however, our data do not clearly allow us to distinguish whether the ongoing star-forming process follows a monolithic collapse or a competitive accretion mechanism.
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