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OBSERVATIONS OF WATER VAPOR TOWARD ORION BN/KL

机译:朝向Orion BN / KL的水蒸气的观测

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We have obtained spectra of the rotational ground-state 1_(10)-1_(01) 556.936 GHz ortho-H_2~(16)O and 1_(10)-1_(01) 547.676 GHz ortho-H_2~(18)O transitions toward Orion BN/KL using the Submillimeter Wave Astronomy Satellite (SWAS). The ortho-H_2~(16)O spectrum shows strong evidence for both a broad (Δv approx= 48 km s~(-1)) and a narrow (Δv approx= 7.5 km s~(-1)) component, while the ortho-H_2~(18)O shows evidence for only a broad (Δv approx= 24 km s~(-1)) component. The broad component emission in both ortho-H_2~(16)O and ortho-H_2~(18)O arises primarily from gas heated within the low- and high-velocity outflows and shocked gas surrounding IRc2 in which the ortho-H_2~(16)O and ortho-H_2~(18)O fractional abundances are estimated to be 3.5 x 10~(-4) and 7 x 10~(-7), respectively. This finding provides further confirmation that water is efficiently and abundantly produced within warm shock-heated gas. We estimate that the hot core plus the compact ridge contribute approx<10% to the ortho-H_2~(16)O integrated intensity within the SWAS beam. The narrow component seen in the ortho-H_2~(16)O spectrum is best fitted by ortho-water emission from the extended ridge (ER) and the higher temperature core of the extended ridge (CER) with a common fractional abundance of 3.3 x 10~(-8). The absence of any discernible narrow component in the ortho-H_2~(18)O spectrum is used to set 3 σ upper limits on the ortho-water fractional abundance within the ER of 7 x 10~(-8) and within the CER of 5.2 x 10~(-7). This implies that within the dense extended quiescent region, gas-phase water is neither a major repository of oxygen nor a major coolant in Orion BN/KL.
机译:我们获得了旋转基态1_(10)-1_(01)556.936 GHz邻-H_2〜(16)O和1_(10)-1_(01)547.676 GHz邻-H_2〜(18)O跃迁的光谱使用亚毫米波天文学卫星(SWAS)向Orion BN / KL行驶。邻-H_2〜(16)O谱显示了宽分量(Δv约48 km s〜(-1))和窄分量(Δv约7.5 km s〜(-1))的有力证据,而ortho-H_2〜(18)O仅显示了一个宽泛的分量(Δv大约= 24 km s〜(-1))。邻位H_2〜(16)O和邻位H_2〜(18)O中的广泛组分发射主要来自在低速和高速流中加热的气体以及IRc2周围的冲击气体,其中邻位H_2〜(( 16)O和邻-H_2〜(18)O的分数丰度分别估计为3.5 x 10〜(-4)和7 x 10〜(-7)。该发现进一步证实了在温暖的冲击加热的气体中有效而大量地产生了水。我们估计,热芯加上致密的脊对SWAS光束内的邻H_2〜(16)O积分强度贡献约<10%。在邻H_2〜(16)O光谱中看到的窄分量最适合由扩展脊(ER)和扩展脊(CER)的高温核心的邻位水发射,其共同分数丰度为3.3 x 10〜(-8)。在邻H_2〜(18)O光谱中不存在任何可辨认的窄成分,可用于在7 x 10〜(-8)的ER和CER的CER内为邻水分数丰度设置3σ上限。 5.2 x 10〜(-7)。这意味着在稠密的扩展静态区域内,气相水既不是Orion BN / KL的主要氧气储存库,也不是主要的冷却液。

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