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首页> 外文期刊>The Astrophysical Journal. Supplement Series >The galactic Census of High- and Medium-Mass Protostars. I. Catalogs and first results from Mopra HCO+ maps
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The galactic Census of High- and Medium-Mass Protostars. I. Catalogs and first results from Mopra HCO+ maps

机译：高中质量原恒星星系普查。一，Mopra HCO +地图的目录和初步结果

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摘要

The Census of High- and Medium-mass Protostars (CHaMP) is the first large-scale, unbiased, uniform mapping survey at sub-parsec-scale resolution of 90GHz line emission from massive molecular clumps in the Milky Way. We present the first Mopra (ATNF) maps of the CHaMP survey region (300° > l > 280°) in the HCO~+ J = 1 → 0 line, which is usually thought to trace gas at densities up to 10~(11)m~(-3). In this paper, we introduce the survey and its strategy, describe the observational and data reduction procedures, and give a complete catalog of moment maps of the HCO~+ J = 1→0 emission from the ensemble of 303 massive molecular clumps. From these maps we also derive the physical parameters of the clumps, using standard molecular spectral-line analysis techniques. This analysis yields the following range of properties: integrated line intensity 1-30Kkms~(-1), peak line brightness 1-7K, linewidth 1-10kms~(-1), integrated line luminosity 0.5-200Kkms~(-1)pc~2, FWHM size 0.2-2.5pc, mean projected axial ratio 2, optical depth 0.08-2, total surface density 30-3000M ⊙pc-2, number density (0.2-30) × 10~9m~(-3), mass 15-8000M ⊙, virial parameter 1-55, and total gas pressure 0.3-700pPa. We find that the CHaMP clumps do not obey a Larson-type size-linewidth relation. Among the clumps, there exists a large population of subthermally excited, weakly emitting (but easily detectable) dense molecular clumps, confirming the prediction of Narayanan etal. These weakly emitting clumps comprise 95% of all massive clumps by number, and 87% of the molecular mass, in this portion of the Galaxy; their properties are distinct from the brighter massive star-forming regions that are more typically studied. If the clumps evolve by slow contraction, the 95% of fainter clumps may represent a long-lived stage of pressure-confined, gravitationally stable massive clump evolution, while the CHaMP clump population may not engage in vigorous massive star formation until the last 5% of their lifetimes. The brighter sources are smaller, denser, more highly pressurized, and closer to gravitational instability than the less bright sources. Our data suggest that massive clumps approach critical Bonnor-Ebert-like states at constant density, while others' suggest that lower-mass clumps reach such states at constant pressure. Evidence of global gravitational collapse of massive clumps is rare, suggesting that this phase lasts <1% of the clumps' lifetime.
机译：高中质量原恒星普查（CHaMP）是第一项大规模，无偏差的均匀制图调查，其银河系中大规模分子团块发出的90GHz线以亚秒级尺度的分辨率。我们展示了HCO〜+ J = 1→0线中CHaMP调查区域（300°> l> 280°）的第一张Mopra（ATNF）图，通常认为其以高达10〜（11）的浓度追踪气体）m〜（-3）。在本文中，我们介绍了这项调查及其策略，描述了观测和数据减少的程序，并给出了来自303个大规模分子团簇的HCO〜+ J = 1→0排放的矩图的完整目录。从这些图中，我们还使用标准分子光谱线分析技术得出了团块的物理参数。该分析产生以下特性范围：积分线强度1-30Kkms〜（-1），峰值线亮度1-7K，线宽1-10kms〜（-1），积分线光度0.5-200Kkms〜（-1）pc 〜2，FWHM尺寸0.2-2.5pc，平均投影轴比2，光学深度0.08-2，总表面密度30-3000M⊙pc-2，数密度（0.2-30）×10〜9m〜（-3），质量15-8000M，病毒参数1-55，总气压0.3-700pPa。我们发现，CHaMP团块不服从拉森型大小-线宽关系。在团块中，存在大量的亚热激发，弱发射（但易于检测）的密集分子团块，这证实了Narayanan等人的预测。在这部分星系中，这些微弱的团块占所有质量团的95％，分子量占87％。它们的性质与通常研究的明亮的大质量恒星形成区不同。如果团块通过缓慢收缩而演化，则95％的微弱团块可能代表着压力受限，重力稳定的大规模团块演化的长期阶段，而CHaMP团块种群可能直到最后5％才参与剧烈的大规模恒星形成他们的一生。与较不明亮的光源相比，较明亮的光源更小，更密，压力更高，并且更接近重力不稳定性。我们的数据表明，大型团块以恒定密度接近临界Bonnor-Ebert态，而其他人则认为较低质量的团块在恒定压力下达到此类状态。大规模团块的全球重力崩溃的证据很少，这表明该阶段持续不到团块寿命的1％。

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