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arXiv 1109.5603astro-ph.CO
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新的Herschel多波长河外边缘螺旋巡天(NHEMESES)

New HErschel Multi-wavelength Extragalactic Survey of Edge-on Spirals (NHEMESES)

B. W. Holwerda, S. Bianchi, M. Baes, R. S. de Jong, J. J. Dalcanton, D. Radburn-Smith, K. Gordon, M. Xilouris

摘要:

边缘上的螺旋星系提供了一个独特的视角来观察螺旋盘的垂直结构,包括恒星和标志性的黑暗尘埃带。这些尘埃带的厚度现在可以解决的第一次与赫歇尔在远红外和亚毫米发射。我们目前NHEMESES,一个正在进行的项目,目标12个边缘上的螺旋星系与PACS和SPIRE仪器赫歇尔。这些垂直分辨的边缘上的螺旋观测将影响当前的几个主题。首先,这些赫歇尔观测将解决ISM的垂直结构是否存在与盘质量的相位变化。在此之前,我们观察到尘埃带形态发生了巨大的变化,因为在巨大的尘埃盘中,尘埃会塌陷成一条细细的尘埃带。如果是这种情况,湍流和重力之间的垂直平衡决定了ISM结构,从而决定了恒星的形成和相关现象(旋臂,棒等)。我们专门针对低质量附近的边缘,以补充现有的赫歇尔观测高质量的边缘上的螺旋(HEROES项目)。其次,结合数据集,加上现有的斯皮策观测,将推动新一代的螺旋盘光谱能量分布模型。这些模型如何尘埃再处理星光热辐射,但尘埃的几何形状仍然是关键的未知数。第三,观测将提供一个准确和公正的普查,偶尔看到的冷尘埃结构延伸出磁盘的平面,当背光的恒星盘。为了说明NHEMESES项目,我们提出了NGC 4244和NGC 891的早期结果,这两个研究的例子是低质量和高质量的边缘螺旋。

英文摘要:

Edge-on spiral galaxies offer a unique perspective on the vertical structure of spiral disks, both stars and the iconic dark dustlanes. The thickness of these dustlanes can now be resolved for the first time with Herschel in far-infrared and sub-mm emission. We present NHEMESES, an ongoing project that targets 12 edge-on spiral galaxies with the PACS and SPIRE instruments on Herschel. These vertically resolved observations of edge-on spirals will impact on several current topics. First and foremost, these Herschel observations will settle whether or not there is a phase change in the vertical structure of the ISM with disk mass. Previously, a dramatic change in dustlane morphology was observed as in massive disks the dust collapses into a thin lane. If this is the case, the vertical balance between turbulence and gravity dictates the ISM structure and consequently star-formation and related phenomena (spiral arms, bars etc.). We specifically target lower mass nearby edge-ons to complement existing Herschel observations of high-mass edge-on spirals (the HEROES project). Secondly, the combined data-set, together with existing Spitzer observations, will drive a new generation of spiral disk Spectral Energy Distribution models. These model how dust reprocesses starlight to thermal emission but the dust geometry remains the critical unknown. And thirdly, the observations will provide an accurate and unbiased census of the cold dusty structures occasionally seen extending out of the plane of the disk, when backlit by the stellar disk. To illustrate the NHEMESES project, we present early results on NGC 4244 and NGC 891, two well studies examples of a low and high-mass edge-on spiral.

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