We used new high spectral resolution observations of propynal (HCCCHO) toward TMC-1 and in the laboratory to update the spectral line catalog available for transitions of HCCCHO—specifically at frequencies lower than 30 GHz, which were previously discrepant in a publicly available catalog. The observed astronomical frequencies provided a high enough spectral resolution that, when combined with high-resolution (∼2 kHz) measurements taken in the laboratory, a new, consistent fit to both the laboratory and astronomical data was achieved. Now with a nearly exact (<1 kHz) frequency match to the J = 2–1 and 3–2 transitions in the astronomical data, using a Markov Chain Monte Carlo analysis, a best fit to the total HCCCHO column density of 7.28−1.94+4.08×1012 cm⁻² was found with a surprisingly low excitation temperature of just over 3 K. This column density is around a factor of 5 times larger than reported in previous studies. Finally, this work highlights that care is needed when using publicly available spectral catalogs to characterize astronomical spectra. The availability of these catalogs is essential to the success of modern astronomical facilities and will only become more important as the next generation of facilities comes online.

中文翻译：

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GBT 上 GOTHAM 大型计划对 TMC-1 的丙炔醛 （HCCCHO） 的高光谱分辨率观测


我们使用了丙醛 （HCCCHO） 对 TMC-1 和实验室的新高光谱分辨率观测，以更新可用于 HCCCHO 跃迁的谱线目录——特别是在低于 30 GHz 的频率下，这在以前公开可用的目录中是不一致的。观测到的天文频率提供了足够高的光谱分辨率，当与实验室进行的高分辨率 （∼2 kHz） 测量相结合时，实现了对实验室和天文数据的新、一致的拟合。现在，由于与天文数据中的 J = 2–1 和 3–2 跃迁的频率几乎精确 （<1 kHz），使用马尔可夫链蒙特卡洛分析，发现 HCCCHO 柱总密度为 7.28−1.94+4.08×1012 cm⁻² 的最佳拟合，激发温度极低，略高于 3 K。该色谱柱密度比之前研究中报道的柱密度高出约 5 倍。最后，这项工作强调，在使用公开可用的光谱表来表征天文光谱时需要小心。这些目录的可用性对于现代天文设施的成功至关重要，并且随着下一代设施的上线，这些目录只会变得更加重要。