A SEARCH FOR INTERSTELLAR CARBON-CHAIN ALCOHOL HC4 OH IN STAR-FORMING REGION L1527 AND DARK CLOUD TMC-1

作者：Araki Mitsunori^*; Takano Shuro; Yamabe Hiromichi; Koshikawa Naohiro; Tsukiyama Koichi; Nakane Aya; Okabayashi Toshiaki; Kunimatsu Arisa; Kuze Nobuhiko

来源：Astrophysical Journal, 2012, 744(2): 163.

DOI：10.1088/0004-637X/744/2/163

• astrochemistry
• ISM: clouds
• ISM: molecules
• radio lines: ISM

We report a sensitive search for the rotational transitions of the carbon-chain alcohol HC4OH in the frequency range 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 x 10(12) and 5.6 x 10(12) 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 %26quot; unsubstituted%26quot; carbon-chain molecule C4H and the sulfur-bearing molecules SO and HCS+ were determined from detected lines in L1527.

• 出版日期2012-1-10
• 单位中国科学院国家天文台