We have developed a method to make a spectral-line-based survey of hot cores, which represent an important stage of high-mass star formation, and applied the method to the data of the FUGIN (FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45 m telescope) survey. First, we select hot core candidates by searching the FUGIN data for the weak hot core tracer lines (HNCO and CH3CN) by stacking, and then we conduct follow-up pointed observations on these candidates in C34S, SO, OCS, HC3N, HNCO, CH3CN, and CH3OH J = 2–1 and J = 8–7 lines to confirm and characterize them. We applied this method to the l = 10°–20° portion of the FUGIN data and identified 22 “HotCores” (compact sources with more than two significant detections of the hot core tracer lines, i.e., SO, OCS, HC3N, HNCO, CH3CN, or CH3OH J = 8–7 lines) and 14 “DenseClumps” (sources with more than two significant detection of C34S, CH3OH J = 2–1, or the hot core tracer lines). The identified HotCores are found to be associated with signposts of high-mass star formation such as ATLASGAL clumps, WISE H ii regions, and Class II methanol masers. Many of the FUGIN HotCores are identified with the Herschel Hi-GAL clumps with a median mass of 6.8 × 102 M⊙ and a median bolometric luminosity of 7.4 × 103 L⊙. Five of the seven HotCores with stronger CH3CN lines exhibit elevated gas temperatures of 50–100 K. These observations suggest that FUGIN HotCores are closely related to the formation of stars with medium to high mass. For those associated with ATLASGAL clumps, their bolometric luminosity to clump mass ratios are consistent with the star formation stages centered at the hot core phase. The catalog of FUGIN HotCores provides a useful starting point for further statistical studies and detailed observations of high-mass star forming regions.

中文翻译：

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FUGIN 热芯调查。一、l = 10°~20°的测量方法及初步结果

我们开发了一种基于谱线的热核心勘测方法，它代表了大质量恒星形成的一个重要阶段，并将该方法应用于 FUGIN（与 Nobeyama 一起进行的森林无偏银河平面成像勘测）的数据45 m 望远镜）调查。首先，我们通过堆叠在 FUGIN 数据中搜索弱热核示踪线（HNCO 和 CH3CN）来选择热核候选，然后我们对 C34S、SO、OCS、HC3N、HNCO、 CH3CN 和 CH3OH J = 2–1 和 J = 8–7 线以确认和表征它们。我们将此方法应用于 FUGIN 数据的 l = 10°–20° 部分，并确定了 22 个“HotCores”（具有两个以上显着检测热芯示踪线的致密源，即 SO、OCS、HC3N、HNCO、 CH3CN, 或 CH3OH J = 8-7 线）和 14 个“密集团块”（具有两个以上显着检测 C34S、CH3OH J = 2-1 或热芯示踪线的源）。发现已识别的热核与大质量恒星形成的路标有关，例如 ATLASGAL 团块、WISE H ii 区域和 II 类甲醇微波激射器。许多 FUGIN 热核被识别为 Herschel Hi-GAL 团块，质量中值为 6.8 × 102 M⊙，辐射热光度中值为 7.4 × 103 L⊙。七个具有更强 CH3CN 谱线的热核中有五个显示出 50-100 K 的高温气体温度。这些观察表明，FUGIN 热核与中质量至高质量恒星的形成密切相关。对于那些与 ATLASGAL 团块相关的人，它们的辐射光度与团块质量比与以热核心阶段为中心的恒星形成阶段一致。FUGIN HotCores 目录为进一步的统计研究和大质量恒星形成区域的详细观察提供了一个有用的起点。