In the past decade, astrochemistry has witnessed an impressive increase in the number of detections of complex organic molecules. Some of these species are of prebiotic interest such as glycolaldehyde, the simplest sugar, or aminoacetonitrile, a possible precursor of glycine. Recently, we have reported the detection of two new nitrogen-bearing complex organics, glycolonitrile and Z-cyanomethanimine, known to be intermediate species in the formation process of ribonucleotides within theories of a primordial RNA-world for the origin of life. In this study, we present deep and high-sensitivity observations toward two of the most chemically rich sources in the galaxy: a giant molecular cloud in the center of the Milky Way (G + 0.693-0.027) and a proto-Sun (IRAS16293-2422 B). Our aim is to explore whether the key precursors considered to drive the primordial RNA-world chemistry are also found in space. Our high-sensitivity observations reveal that urea is present in G + 0.693-0.027 with an abundance of ∼5 × 10⁻¹¹. This is the first detection of this prebiotic species outside a star-forming region. Urea remains undetected toward the proto-Sun IRAS16293-2422 B (upper limit to its abundance of ≤2 × 10⁻¹¹). Other precursors of the RNA-world chemical scheme such as glycolaldehyde or cyanamide are abundant in space, but key prebiotic species such as 2-amino-oxazole, glyceraldehyde, or dihydroxyacetone are not detected in either source. Future more sensitive observations targeting the brightest transitions of these species will be needed to disentangle whether these large prebiotic organics are certainly present in space.

中文翻译：

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朝着星际介质检测尿素和寻找2-氨基-恶唑和简单糖的RNA世界迈进。

在过去的十年中，天体化学见证了复杂有机分子检测数量的惊人增长。这些物种中的某些具有益生元价值，例如乙醇醛，最简单的糖或氨基乙腈（可能是甘氨酸的前体）。最近，我们报告了两种新的含氮复合有机物的检测，乙醇腈和Z-氰基甲亚胺，它们已知是原始RNA世界理论中生命起源起源于核糖核苷酸形成过程中的中间物种。在这项研究中，我们对银河系中两个化学含量最高的来源提供了深层和高灵敏度的观测结果：银河系中央的巨大分子云（G + 0.693-0.027）和原始太阳（IRAS16293- 2422 B）。我们的目的是探索在太空中是否还发现了被认为是驱动原始RNA世界化学的关键前体。我们的高灵敏度观察表明，尿素以G + 0.693-0.027的形式存在，其丰度约为5×10 ^-11。这是在恒星形成区域之外首次检测到该益生元物种。朝着原始IRAS16293-2422 B方向未检测到尿素（其丰度≤2×10 ^-11的上限）。RNA世界化学方案的其他前体，例如乙醇醛或氰胺，在空间上很丰富，但是在两种来源中均未检测到关键的益生元物种，例如2-氨基-恶唑，甘油醛或二羟基丙酮。需要未来针对这些物种最明亮过渡的更为敏感的观察结果，以弄清这些大型益生元有机物是否确实存在于太空中。