论文标题
W51A中Nifs/altair的W51a中超级合理{H} {2}区域的近红外光谱
Near-Infrared Spectroscopy of Ultracompact \ion{H}{2} regions in W51A with NIFS/ALTAIR
论文作者
论文摘要
W51a是巨型\ ion {h} {2}区域W51的最活跃的星形区域。它具有两个巨大的原始群体W51E和W51 \，IRS2，它们在银河系中非常罕见。我们旨在确定新出生的大型恒星和UCHII地区，以得出其距离和年龄。我们在W51a子区域中用NIFS+AltAIR进行了IFU观测值。距离模量是使用$ K $带中的频谱分类获得的，并且是适合内部银河平面的变红定律。我们得出了其中五种距离和光谱类型，范围从O8到O9.5，类似于从无线电连续数据中得出的距离，除了我们分配了后来的光谱类型的两个源。我们包含了另外七个对其他作品进行精确光谱分类的对象，这使我们能够更好地限制距离估计值。我们的分光光度计距离d = 4.80 \，$ \ pm $ \，1.27 \，KPC与从银河旋转模型和三角式视差衍生的距离非常吻合，将其放置在Sagittarius Arm的切线附近的区域。我们得出的结论是，这项工作中研究的星星的年龄为1.5-4 Myr，比迄今为止的年龄大得多。
W51A is the most active star formation region of the Giant \ion{H}{2} region W51. It harbors the two massive proto-clusters W51e and W51\,IRS2, which are very rare in the Galaxy. We aim to identify the new born massive stars and UCHII regions to derive its distance and age. We performed IFU observations with NIFS+ALTAIR of nine targets in the W51A sub-region. The distance modulus was obtained using the spectral classification in the $K$-band and a reddening law appropriate to the inner Galactic plane. We derived the distance and the spectral types for five of them, ranging from O8 to O9.5, similar to those derived from radio continuum data, except for two sources that we assigned somewhat a later spectral type. We included another seven objects with precise spectral classification from other works, which allowed us to better constrain the distance estimate. Our spectrophotometric distance d=4.80\,$\pm$\,1.27\,kpc is in good agreement with those derived from the Galactic rotation model and trigonometric parallaxes, placing the region near the tangent point of the Sagittarius arm. We conclude that the stars studied in this work have an age spread of 1.5-4 Myr, substantially older than thought to date.
