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arXiv 2401.04760astro-ph.GA
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使用ALMA在3毫米波段对IRAS16293-2422 B进行大质量复杂有机分子的深度搜寻

A deep search for large complex organic species toward IRAS16293-2422 B at 3 mm with ALMA

P. Nazari, J. S. Y. Cheung, J. Ferrer Asensio, N. M. Murillo, E. F. van Dishoeck, J. K. Jørgensen, T. L. Bourke, K. -J. Chuang, M. N. Drozdovskaya, G. Fedoseev,… 展开作者

P. Nazari, J. S. Y. Cheung, J. Ferrer Asensio, N. M. Murillo, E. F. van Dishoeck, J. K. Jørgensen, T. L. Bourke, K. -J. Chuang, M. N. Drozdovskaya, G. Fedoseev, R. T. Garrod, S. Ioppolo, H. Linnartz, B. A. McGuire, H. S. P. Müller, D. Qasim, S. F. Wampfler

AI总结:

本研究使用ALMA在3mm波段对IRAS 16293-2422 B进行深度搜寻,识别了31种分子,发现Band 3与Band 7的柱密度结果相似,但未探测到甘油等更大复杂分子,表明需更低频的深度巡天。

摘要:

复杂有机分子(COMs)已在原恒星系统中被普遍探测到。然而,在较短波长(~0.8mm)处,由于毫米级尘埃不透明度增加、谱线混淆以及不利的配分函数,探测较大分子比在较长波长(~3mm)处更为困难。我们旨在搜寻IRAS 16293-2422 B的ALMA Band 3光谱中存在的大分子(>8个原子)。我们在光谱中搜寻了70多种分子,并尽可能多地识别谱线。光谱设置专门针对丙醇和甘油等三碳分子。我们识别出31种分子的谱线,包括许多含氧COMs(如CH3OH和c-C2H4O)以及少数含氮和含硫分子(如HOCH2CN和CH3SH)。探测到的最大分子是gGg-(CH2OH)2和CH3COCH3。我们未探测到甘油或丙醇,但提供了它们的上限,这与以往的实验室和观测研究相符。Band 3的谱线密度在频率空间中仅比Band 7低约2.5倍。在Band 3中$\gtrsim 6σ$水平的已探测谱线中,约25-30%无法被识别,表明需要更多转动光谱的实验室数据。我们发现Band 3和Band 7之间COMs的柱密度和柱密度比相似(相差在约2倍以内)。IRAS 16293-2422 B在源外位置的尘埃光深对柱密度和柱密度比的影响极小。此外,对于温暖原恒星,长波光谱不仅拥挤,而且需要更长的积分时间才能达到相同的灵敏度极限。3mm搜寻尚未在温暖源中探测到更大、更复杂的分子。需要进行全面的深度ALMA Band 2-3(即3-4mm)巡天,以评估低频数据是否有潜力在温暖源中揭示更复杂的分子。

英文摘要:

Complex organic molecules (COMs) have been detected ubiquitously in protostellar systems. However, at shorter wavelengths (~0.8mm) it is more difficult to detect larger molecules than at longer wavelengths (~3mm) because of the increase of millimeter dust opacity, line confusion, and unfavorable partition function. We aim to search for large molecules (>8 atoms) in the ALMA Band 3 spectrum of IRAS 16293-2422 B. We search for more than 70 molecules and identify as many lines as possible in the spectrum. The spectral settings were set to specifically target three-carbon species such as propanol and glycerol. We identify lines of 31 molecules including many oxygen-bearing COMs such as CH3OH and c-C2H4O and a few nitrogen- and sulfur-bearing ones such as HOCH2CN and CH3SH. The largest detected molecules are gGg-(CH2OH)2 and CH3COCH3. We do not detect glycerol or propanol but provide upper limits for them which are in line with previous laboratory and observational studies. The line density in Band 3 is only ~2.5 times lower in frequency space than in Band 7. From the detected lines in Band 3 at a $\gtrsim 6σ$ level, ~25-30% of them could not be identified indicating the need for more laboratory data of rotational spectra. We find similar column densities and column density ratios of COMs (within a factor ~2) between Band 3 and Band 7. The effect of dust optical depth for IRAS 16293-2422 B at an off-source location on column densities and column density ratios is minimal. Moreover, for warm protostars, long wavelength spectra are not only crowded, but also take longer integration times to reach the same sensitivity limit. The 3mm search has not yet resulted in detection of larger and more complex molecules in warm sources. A full deep ALMA Band 2-3 (i.e., 3-4 mm) survey is needed to assess whether low frequency data have the potential to reveal more complex molecules in warm sources.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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