Laboratory submillimeter-wave spectroscopy of interstellar deuterated molecules : evolution timescale determination of dark cloud cores

本文的主要课题是星际氘的高灵敏度亚毫米波光谱，旨在从氘的分馏程度估计黑云核心的化学演化年龄。在三年的时间里取得了以下成果：目前覆盖600千兆赫的高灵敏度亚毫米波光谱仪在目前的赠款和其他来源的帮助下得到改进，以覆盖500-830千兆赫的新频率区域。新的光谱仪被用来研究如下所示的几种星际氘。利用DC0^+和HCO^+的丰度比，结合新的气相化学反应标准模型网络，将提出的由氘分馏度估算黑云核化学演化年龄的方法应用于金牛座分子云1号的两个黑云核，即氰聚峰和氨峰。这是第一个用氘分馏度估算黑云核的化学演化年龄的例子。2 .两者之间氘分馏的差异可以用超过10^5年的演化年龄来解释。上述方法也适用于L134N的两个云核，即东北NH_3核和南部NH_3核，L134N是一个典型的无能量暗云。通过对岩心中氘分馏度和C/0损耗的分析表明，南侧岩心比东北侧岩心处于更成熟的演化阶段。C/0损耗也反映了岩心的演化程度。最近在南岩心检测到的高分馏NH_2D和NHD_2的存在与南岩心高C/0损耗相一致。用一种新型的高灵敏度亚毫米波光谱仪研究了HDC1^+和PHD两种星际氘。由于磷、氢和氘原子核的精细和超精细结构，PHD的光谱模式非常复杂。对复杂光谱线的详细分析导致磷、氢和氘的超精细耦合常数的精确测定。由PHD、PH_2和PD_2的观测值推导出PH_2中氢和PD_2中氘的磁偶极耦合张量的主轴和主值。PH_2中氢磁耦合张量的主轴与PH键成2.3^0的夹角。这个结果是一个罕见的例子，其中超精细耦合张量和相关的化学键之间的关系是明确指出的。少

The main subject of the present proposal is high-sensitivity submillimeter-wave spectroscopy of interstellar deuterides, aiming to estimate the chemical evolutionary age of dark cloud cores from the degree of deuterium fractionation. The following results are obtained during three years proposed.1. The present high-sensitivity submillimeter-wave spectrometer covering up to 600 GHz was improved to cover a new frequency region of 500-830 GHz, aided by the present Grant-in Aid and other sources. The new spectrometer was used to study a few interstellar deuterides given below.2. The proposed method of estimating the chemical evolutionary age of dark cloud cores from the degree of deuterium fractionation is applied to two dark cloud cores, cyanopolyyne peak and ammonia peak, of Taurus Molecular Cloud 1, using the abundance ratios between DC0^+ and HCO^+ combined with the new standard model network of gas-phase chemical reactions. The difference in deuterium fractionation between the two cor … More es is explained by a time difference in the evolutionary age of more than 10^5 yr. This is the first example of the chemical evolutionary age of dark cloud cores estimated from the degree of deuterium fractionation.3. The method proposed above is also applied to two cloud cores, the northeast NH_3 core and the southern NH_3 core, of L134N which is a typical dark cloud having no energy sources. An analysis including the degree of deuterium fractionation and C/0 depletion in cores shows that the southern core is in a more evolved stage than the northeast core. The C/0 depletion also indicates the degree of core evolution. The existence of highly fractionated NH_2D and NHD_2 recently detected at the southern core is consistent with the high C/0 depletion in the southern core.4. Two interstellar deuterides, HDC1^+ and PHD were studied with a new high-sensitivity submillimeter-wave spectrometer. Spectral patterns of PHD were very complicated due to fine and hyperfine structures of phosphorus, hydrogen and deuterium nuclei. A detailed analysis of complicated spectral lines resulted in a precise determination of the hyperfine coupling constants of phosphorus, hydrogen, and deuterium. The principal axis and principal values of the magnetic dipole coupling tensors of hydrogen in PH_2 and deuterium in PD_2 were derived from the observed values of PHD, PH_2 and PD_2. The principal axis of the hydrogen magnetic coupling tensor in PH_2 makes an angle of 2.3^0 with the PH bond. This result is one of rare cases in which a relation between the hyperfine coupling tensor and the related chemical bond is clearly indicated. Less