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arXiv · 1110.4453

A Search for Interstellar Carbon Chain Alcohol HC4OH in Star-Forming Region L1527 and Dark Cloud TMC-1

Mitsunori Araki·Shuro Takano·Hiromichi Yamabe·Naohiro Koshikawa·Koichi Tsukiyama·Aya Nakane·Toshiaki Okabayashi·Arisa Kunimatsu·Nobuhiko Kuze
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Abstract

We report a sensitive search for the rotational transitions of the carbon chain alcohol HC4OH in the frequency range of 21.2-46.7 GHz in the star-forming region L1527 and the dark cloud TMC-1. The motivation was laboratory detection of HC4OH by microwave spectroscopy. Despite achieving rms noise levels of several millikelvin in the antenna temperature using the 45 m telescope at Nobeyama Radio Observatory, the detection was not successful, leading to 3 sigma upper limits corresponding to the column densities of 2.0 \times 1012 and 5.6 \times 1012 cm-2 in L1527 and TMC-1, respectively. These upper limits indicate that [HC4OH]/[HC5N] ratios are less than 0.3 and 0.1 in L1527 and TMC-1, respectively, where HC5N is an HC4-chain cyanide and HC4OH is a hydroxide. These ratios suggest that the cyano carbon chain molecule dominates the hydroxyl carbon chain molecule in L1527 and TMC-1. This is contrary to the case of saturated compounds in hot cores, e.g., CH3OH and CH3CN, and can be a chemical feature of carbon chain molecules in L1527 and TMC-1. In addition, the column densities of the "unsubstituted" carbon chain molecule C4H and the sulfur-bearing molecules SO and HCS+ were determined from detected lines in L1527.

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Mitsunori Araki, Shuro Takano, Hiromichi Yamabe, Naohiro Koshikawa, Koichi Tsukiyama, Aya Nakane, Toshiaki Okabayashi, Arisa Kunimatsu, Nobuhiko Kuze. 2011-10-20. A Search for Interstellar Carbon Chain Alcohol HC4OH in Star-Forming Region L1527 and Dark Cloud TMC-1. https://doi.org/10.1088/0004-637x%2F744%2F2%2F163

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