인문학
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자연과학
공학
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DBpia AI
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AI 아이디어
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Citeasy
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지원사업
학술연구/단체지원/교육 등 연구자 활동을 지속하도록 DBpia가 지원하고 있어요.
커뮤니티
연구자들이 자신의 연구와 전문성을 널리 알리고, 새로운 협력의 기회를 만들 수 있는 네트워킹 공간이에요.
초록·키워드
Aims . We test the use of three common molecular ions, ortho-H 2 D + (oH 2 D + ), N 2 H + , and DCO + , as probes of the internal structure and kinematics of a dense, starless molecular cloud core. Methods . The pre-stellar core H-MM1 in Ophiuchus was mapped in the oH 2 D + (1 10 − N 2 H + (4 − 3), and DCO + (5 − 4) lines with the Large APEX sub-Millimeter Array (LAsMA) multi-beam receiver of the Atacama Pathfinder EXperiment (APEX) telescope. We also ran a series of chemistry models to predict the abundance distributions of the observed molecules, and to estimate the effect of the cosmic-ray ionisation rate on their abundances. Results . The three line maps show different distributions. The oH 2 D + map is extended and outlines the general structure of the core, N 2 H + mainly shows the density maxima, and the DCO + emission peaks are shifted towards one edge of the core where a region of enhanced desorption had previously been found. According to the chemical simulation, the fractional oH 2 D + abundance remains relatively high in the centre of the core, and its column density correlates strongly with the cosmic-ray ionisation rate, ζ H 2 . Simulated line maps constrain the cosmic-ray ionisation rate to be low, between 5 × 10 −18 s −1 and 1 × 10 −17 s −1 in the H-MM1 core. This estimate agrees with the gas temperature measured in the core. Conclusions . The present observations show that very dense, cold gas in molecular clouds can be traced by mapping the ground-state line of oH 2 D + and high- J transitions of DCO + and N 2 H + , despite the severe depletion of the latter two molecules. Modelling line emission of oH 2 D + provides a straightforward method of determining the cosmic-ray ionisation rate in dense clouds, where the primary ion, H 3 + , is not observable.
인공지능 문자 인식 모델을 통해 추출된 텍스트로, 일부 오타나 오류가 포함될 수 있으나 지속적으로 개선 중입니다.
오류를 발견하셨다면 해당 부분을 드래그한 후 ' 를 통해 신고해주세요.
오류를 발견하셨다면 해당 부분을 드래그한 후 ' 를 통해 신고해주세요.
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