We present results based on ${2{^{\prime \prime}_{.}}5}$-resolution observations using the Atacama Large Millimeter/Submillmeter Array (ALMA) of the Galactic center molecular cloud G−0.02−0.07, or the 50 km s−1 molecular cloud (50 MC), in the SO (NJ = 22–11) line and 86 GHz continuum emission, the combination of which is considered to trace “hot molecular core candidates” (HMCCs) appearing in the early stage of massive-star formation. In the 86 GHz continuum image, we identified nine dust cores in the central part of the 50 MC, in which four famous compact H ii regions are located. No new ultra-compact H ii regions were found. We also identified 28 HMCCs in the 50 MC with the SO line. The overall SO distribution had no clear positional correlation with the identified H ii regions. The HMCCs in the 50 MC showed a variety of association and non-association with dust and Class I CH3OH maser emissions. The variety suggests that they are not in a single evolutionary stage or environment. Nevertheless, the masses of the identified HMCCs were found to be well approximated by a single power law of their radii, MLTE/(M⊙) = 5.44 × 105 [r/(pc)]2.17 at Tex = 50–100 K. The derived HMCC masses were larger than those of the molecular cores with the same radii in the 50 MC, and also than those of the molecular clumps in the Galactic disk. Additional observations are needed to confirm the nature of these HMCCs in the 50 MC.

中文翻译：

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银河系中心 50 km s−1 分子云中的热分子核心候选者

我们使用银河中心分子云 G−0.02−0.07 的阿塔卡马大毫米/亚毫米阵列 (ALMA) 提供基于 ${2{^{\prime \prime}_{.}}5}$ 分辨率观测的结果，或 50 km s-1 分子云 (50 MC)，在 SO (NJ = 22-11) 线和 86 GHz 连续发射中，它们的组合被认为是追踪出现在大质量恒星形成的早期阶段。在 86 GHz 连续谱图像中，我们在 50 MC 的中心部分识别出 9 个尘埃核心，其中有四个著名的紧凑 H ii 区域。没有发现新的超紧凑 H ii 区域。我们还用 SO 线在 50 个 MC 中确定了 28 个 HMCC。总体 SO 分布与已识别的 H ii 区域没有明显的位置相关性。50 MC 中的 HMCC 显示出与粉尘和 I 类 CH3OH 微波激射发射的多种关联和非关联。这种多样性表明它们并不处于单一的进化阶段或环境中。尽管如此，发现已识别的 HMCC 的质量很好地近似于其半径的单一幂律，MLTE/(M⊙) = 5.44 × 105 [r/(pc)]2.17，Tex = 50–100 K。衍生出的 HMCC 质量大于 50 MC 中具有相同半径的分子核心，也大于银盘中的分子团块。需要额外的观察来确认 50 MC 中这些 HMCC 的性质。在 Tex = 50–100 K 时，发现已识别的 HMCC 的质量可以通过其半径的单一幂律 MLTE/(M⊙) = 5.44 × 105 [r/(pc)]2.17 很好地近似。导出的 HMCC质量大于 50 MC 中具有相同半径的分子核心，也大于银盘中的分子团块。需要额外的观察来确认 50 MC 中这些 HMCC 的性质。在 Tex = 50–100 K 时，发现已识别的 HMCC 的质量可以通过其半径的单一幂律 MLTE/(M⊙) = 5.44 × 105 [r/(pc)]2.17 很好地近似。导出的 HMCC质量大于 50 MC 中具有相同半径的分子核心，也大于银盘中的分子团块。需要额外的观察来确认 50 MC 中这些 HMCC 的性质。