The Expansion Rate of and Distance to G5.89–0.39
The Expansion Rate of and Distance to G5.89–0.39
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G5.89–0.39的扩张速度和距离
DOI：
10.1086/311230
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
D. O. S. Wood
中科院分区：
文献类型：
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作者：
J. M. Acord;E. Churchwell;D. O. S. Wood
利用三次VLA观测，测量了超致密HⅡ区G5.89-0.39区电离壳的膨胀率。星云壳层正以2.5±0.5 Ma yr-1的速度膨胀。从角半径和膨胀率，我们发现一个动力学年龄为600年+250年−125年。结合星云发射和H射电复合线谱的模型，我们估计S−1的膨胀速度约为35公里，震源距离为2.0+0.7−0.4kpc。这比之前大多数估计的2.5-3克朗略有接近。我们没有看到可能与SiO中的分子外流有关的东北-西南扩展的证据；然而，我们的数据与之前对南北流的观测一致，表明SiO流可能起源于视线上的另一颗年轻恒星。
The expansion rate of the ionized shell in the ultracompact H II region G5.89-0.39 has been measured using three VLA observations spanning 5.3 yr. The nebular shell is expanding at a rate of 2.5±0.5 mas yr-1. From the angular radius and expansion rate, we find a dynamical age of 600+ 250−125 yr. Combined with a model for the nebular emission and H radio recombination line spectra, we estimate an expansion velocity of about 35 km s−1 and a source distance of 2.0+ 0.7−0.4 kpc. This is slightly closer than most previous estimates of 2.5-3 kpc. We see no evidence for northeast-southwest expansion that might be associated with the molecular outflow seen in SiO; however, our data are consistent with previous observations of a north-south flow, indicating that the SiO flow may originate from another young star along the line of sight.