New Distance and Revised Natures of High-Mass Star Formation in G5.89–0.39
New Distance and Revised Natures of High-Mass Star Formation in G5.89–0.39
复制标题
DOI：
10.1093/pasj/63.1.31
复制
发表时间：
2010-12
影响因子：
2.3
通讯作者：
K. Motogi;K. Sorai;A. Habe;M. Honma;H. Kobayashi;Katsuhisa Sato
中科院分区：
文献类型：
--
作者：
K. Motogi;K. Sorai;A. Habe;M. Honma;H. Kobayashi;Katsuhisa Sato
本文报道了用VLBI射电天体测量探测仪（VERA）对高质量恒星形成区G5.89-0.39的22 GHz H2O脉泽的天体测量观测结果。新得到的距离为1.28^{+0.09}-0.08} kpc，是最精确的，比以前的值更接近。我们修改了物理参数，并根据新的距离重新考虑了G5.89-0.39的性质，如下所示。(1)超致密（UC）HII区域的电离星星是一颗晚O型（O 8 - 8.5）零龄主序星（ZAMS）星星，符合先前建立的基于其红外光谱线发射的限制。(2)在O型ZAMS星星位置上的新月状脉泽排列可能追踪到吸积盘（或其残余物），这表明该星星还很年轻，星周物质还没有完全蒸发。(3)虽然修正后的东西流出的质量已被减少，它仍然相当大（100 Msun），这表明，一个显着的部分质量是夹带的材料和动力学年龄显着低估了实际的流出年龄。我们的新推导的距离强调，G5.89-0.39是最近的目标之一，以调查正在进行的高质量星星的形成和演化，在一个紧凑的集群包含一个年轻的O-型星星。
We report on the astrometric observations of the 22 GHz H2O masers in the high mass star-forming region G5.89-0.39 with VERA (VLBI Exploration of Radio Astrometry). Newly derived distance of 1.28^{+0.09}_{-0.08} kpc is the most precise and significantly nearer than previous values. We revised physical parameters and reconsidered nature of G5.89-0.39 based on the new distance as follows. (1) The ionizing star of the ultra compact (UC) HII region is a late O-type (O8 - 8.5) zero age main sequence (ZAMS) star, consistent with previously established limits based on its infrared spectral line emission. (2) Crescent-like maser alignment at the position of the O type ZAMS star may trace accretion disk (or its remnant), which suggests that the star is still young and before complete evaporation of circumstellar materials. (3) Although the revised mass for the east-west outflow has been reduced, it still quite large (100 Msun) which indicates that a significant fraction of the mass is entrained material and that the dynamical age significantly underestimates the actual outflow age. Our newly-derived distance emphasizes that G5.89-0.39 is one of the nearest targets to investigate ongoing high-mass star formation and evolution in a compact cluster containing a young O-type star.