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arXiv 0712.0218astro-ph
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用Mopra望远镜对人马座B2区多条3-mm分子谱线的光谱成像

Spectral imaging of the Sagittarius B2 region in multiple 3-mm molecular lines with the Mopra telescope

P. A. Jones, M. G. Burton, M. R. Cunningham, K. M. Menten, P. Schilke, A. Belloche, S. Leurini, J. Ott, A. J. Walsh

备注：
22 pages, 12 figures, 5 tables. MNRAS in press. Version 2 with small changes after referee's comments
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摘要：

利用莫普拉望远镜，我们对人马座B2周围5 x 5弧分^2的区域进行了一次3毫米谱线成像测量。我们几乎覆盖了81.7到113.5 GHz的整个频谱范围，2.2 MHz宽的频谱通道或~ 6 km/s，并观察到24条线，0.033 MHz宽，或~ 0.1 km/s通道。我们讨论了约50条线的分布，并提出了38条线的速度积分发射图像。此外，我们还探测到了大约120条谱线，主要集中在特别富含谱线的Sgr B2（N）源。有显着差异的分子发射，指向整个区域的丰度和激发差异。七个不同的空间位置被确定为发射物种，包括在IR到射电连续图像中看到的Sgr B2（N），（M）和（S）的突出恒星形成核心附近的峰值。其他特征是Sgr B2 N-M-S核心以北的“北脊”和“北云”，“东南峰”和“西脊”。通过C^{18}O可以明显看出，柱密度在Sgr B2（N）和（M）核心处达到峰值，在这些核心处，强吸收在其他通常明亮的谱线（如HCO^{+}、HCN和HNC）中也是明显的。大多数分子沿着Sgr B2 N-M-S核心以西的山脊线，环绕核心并向东北方向延伸到北云。这在物质HC_{3} N、CH_{3} CN、CH_{3} OH和OCS中最为明显。他们被发现是更接近分布的冷尘埃跟踪的亚毫米连续比中红外线或无线电连续看到的温暖的尘埃。相比之下，除了在Sgr B2（N）和（M）核心位置处的强吸收外，分子CN在整个映射区域上相当均匀。

英文摘要：

Using the Mopra telescope, we have undertaken a 3-mm spectral-line imaging survey of a 5 x 5 arcmin^2 area around Sgr B2. We covered almost the complete spectral the range from 81.7 to 113.5 GHz, with 2.2 MHz wide spectral channels or ~ 6 km/s, and have observed 24 lines, with 0.033 MHz wide, or ~ 0.1 km/s channels. We discuss the distribution of around 50 lines, and present velocity-integrated emission images for 38 of the lines. In addition, we have detected around 120 more lines, mostly concentrated at the particularly spectral line-rich Sgr B2(N) source. There are significant differences in molecular emission, pointing to both abundance and excitation differences throughout the region. Seven distinct spatial locations are identified for the emitting species, including peaks near the prominent star forming cores of Sgr B2(N), (M) and (S) that are seen in IR-to-radio continuum images. The other features are a 'North Ridge' and a 'North Cloud' to the north of the Sgr B2 N-M-S cores, a 'South-East Peak' and a 'West Ridge'. The column density, as evident through C^{18}O, peaks at the Sgr B2(N) and (M) cores, where strong absorption is also evident in otherwise generally bright lines such as HCO^{+}, HCN and HNC. Most molecules trace a ridge line to the west of the Sgr B2 N-M-S cores, wrapping around the cores and extending NE to the North Cloud. This is most clearly evident in the species HC_{3}N, CH_{3}CN, CH_{3}OH and OCS. They are found to be closer in distribution to the cooler dust traced by the sub-mm continuum than either the warmer dust seen in the mid-IR or to the radio continuum. The molecule CN, in contrast, is reasonably uniform over the entire region mapped, aside from strong absorption at the positions of the Sgr B2(N) and (M) cores.

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