标题： 直接成像和光谱学研究在MWC 758中驱动螺旋臂的巨大原行星 显示英文标题

标题： Direct images and spectroscopy of a giant protoplanet driving spiral arms in MWC 758

摘要： 理解原行星盘中螺旋臂的驱动力仍然是一个挑战，这是由于年轻巨行星的亮度较暗。MWC 758拥有一个具有双臂螺旋结构的原行星盘，该结构被认为是由外部巨行星驱动的。我们展示了新的热红外观测结果，这些观测结果对更红（即更冷或被更多遮挡）的行星比短波长的以往观测更为敏感。我们在距离恒星约100天文单位的投影距离处探测到了一个巨行星MWC 758c。MWC 758c的光谱不同于盘的其余部分，并与行星大气的发射一致，其有效温度为500 +/- 100 K，对于较低的消光水平（AV<30），或者是一个温度更高但消光水平更高的物体。这两种情况都与导致螺旋臂形成的伴星的预测特性相符。MWC 758c提供了证据，表明原行星盘中的螺旋臂可能由冷巨行星或光学发射高度被遮挡的行星引起。MWC 758c不仅是最年轻的巨行星之一，也是最冷和/或被遮挡最多的行星之一。此外，MWC 758c是首批在拥有原行星盘的系统中被观测到的行星之一。 显示英文摘要

摘要： Understanding the driving forces behind spiral arms in protoplanetary disks remains a challenge due to the faintness of young giant planets. MWC 758 hosts such a protoplanetary disk with a two-armed spiral pattern that is suggested to be driven by an external giant planet. We present new thermal infrared observations that are uniquely sensitive to redder (i.e., colder or more attenuated) planets than past observations at shorter wavelengths. We detect a giant protoplanet, MWC 758c, at a projected separation of ~100 au from the star. The spectrum of MWC 758c is distinct from the rest of the disk and consistent with emission from a planetary atmosphere with Teff = 500 +/- 100 K for a low level of extinction (AV<30), or a hotter object with a higher level of extinction. Both scenarios are commensurate with the predicted properties of the companion responsible for driving the spiral arms. MWC 758c provides evidence that spiral arms in protoplanetary disks can be caused by cold giant planets or by those whose optical emission is highly attenuated. MWC 758c stands out both as one of the youngest giant planets known, and also as one of the coldest and/or most attenuated. Furthermore, MWC 758c is among the first planets to be observed within a system hosting a protoplanetary disk.