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arXiv 1106.4840astro-ph.GA
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斯皮策银河系恒星结构巡天(S4G)中的大设计和絮状螺旋

Grand Design and Flocculent Spirals in the Spitzer Survey of Stellar Structure in Galaxies (S4G)

Debra Meloy Elmegreen, the S4G Team

摘要:

斯皮策银河系恒星结构巡天(Spitzer Survey of Stellar Structure in Galvanian,S4G)中的46个星系的旋臂性质被测量到3.6 μ,在那里消光很小,老恒星占主导地位。该样品包括絮凝,多臂,并与广泛的哈勃和酒吧类型的大设计类型。我们发现,大多数光学絮凝星系也絮凝在中红外,因为恒星形成与恒星密度波不相关,而多臂和大设计星系有潜在的恒星波。臂间对比度从絮状增加到多臂,再到宏伟的设计星系和后来的哈勃类型。与以前的调查相比,可以在盘中进一步追踪结构。有些螺旋在中间半径处达到顶峰,而另一些则不断上升或下降,这取决于哈勃和棒的类型。我们发现的证据,在NGC 4321的手臂力量的定期和对称调制。在早期类型的螺旋中,棒倾向于长,高振幅和平坦轮廓,臂对比度随着棒末端的半径而减小,而在晚期哈勃类型中,它们倾向于短,低振幅和指数轮廓,臂对比度恒定或随着半径而增加。较长的条形图往往具有较大的振幅和较强的臂。

英文摘要:

Spiral arm properties of 46 galaxies in the Spitzer Survey of Stellar Structure in Galaxies (S4G) were measured at 3.6mu, where extinction is small and the old stars dominate. The sample includes flocculent, multiple arm, and grand design types with a wide range of Hubble and bar types. We find that most optically flocculent galaxies are also flocculent in the mid-IR because of star formation uncorrelated with stellar density waves, whereas multiple arm and grand design galaxies have underlying stellar waves. Arm-interarm contrasts increase from flocculent to multiple arm to grand design galaxies and with later Hubble types. Structure can be traced further out in the disk than in previous surveys. Some spirals peak at mid-radius while others continuously rise or fall, depending on Hubble and bar type. We find evidence for regular and symmetric modulations of the arm strength in NGC 4321. Bars tend to be long, high amplitude, and flat-profiled in early type spirals, with arm contrasts that decrease with radius beyond the end of the bar, and they tend to be short, low amplitude, and exponential-profiled in late Hubble types, with arm contrasts that are constant or increase with radius. Longer bars tend to have larger amplitudes and stronger arms.

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