Hot Cores in W49N and the Timescale for Hot Core Evolution
Hot Cores in W49N and the Timescale for Hot Core Evolution
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W49N 中的热门核心以及热门核心演进的时间表
DOI：
10.1086/319498
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
W. Goss
中科院分区：
文献类型：
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作者：
D. Wilner;C. D. De Pree;W. Welch;W. Goss
我们展示了使用 Berkeley-Illinois-Maryland Association 阵列在连续谱和 CH3CN J = 12-11 线中 1.4 mm 波长下对恒星形成区域 W49N 进行的亚角秒分辨率观测。连续谱图像的分辨率为 0.”18 (2000 AU)，显示了许多先前识别的超紧凑 H II 区域和至少一个新源，其陡峭的短波长光谱表明灰尘排放。这种紧凑的粉尘浓度也显示出该地区最强的 CH3CN 排放。 CH3CN 发射的额外峰值可能标志着其他深埋年轻大质量恒星产生的热核心，这些恒星可能是 O 型恒星的前身，例如为超致密 H II 区域提供动力的恒星。 W49N 中发现的热核与超致密 H II 区域的数量比率提供了这些早期演化阶段的相对时间尺度的测量。尽管样本很小，但源计数表明热核寿命很可能短于超紧凑 H II 区寿命，但与之相当。
We present subarcsecond resolution observations of the star-forming region W49N made with the Berkeley-Illinois-Maryland Association array at 1.4 mm wavelength in the continuum and CH3CN J = 12-11 lines. The continuum image, at a resolution of 0.″18 (2000 AU), shows many of the previously identified ultracompact H II regions and at least one new source whose steep spectrum to short wavelengths indicates dust emission. This compact dust concentration also shows the strongest CH3CN emission in the region. Additional peaks of CH3CN emission likely mark hot cores produced by other deeply embedded young massive stars that may be precursors to O-type stars like those that power the ultracompact H II regions. The number ratio of hot cores to ultracompact H II regions found in W49N provides a measure of the relative timescales of these early evolutionary phases. Although the samples are small, the source counts suggest that the hot core lifetime is most likely shorter than, but comparable to, the ultracompact H II region lifetime.