Hα Imaging of Early-Type (Sa-Sab) Spiral Galaxies. I.
Hα Imaging of Early-Type (Sa-Sab) Spiral Galaxies. I.
复制标题
早期型 (Sa-Sab) 螺旋星系的 Hα 成像 I。
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
N. Devereux
中科院分区：
文献类型：
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作者：
S. Hameed;N. Devereux
给出了27个邻近早型（Sa-Sab）旋涡星系的Hα和连续谱图像。与普遍的看法相反，这些图像揭示了其中一些星系中大量的大质量星星的形成。对Hα形态的测定和对Hα光度的测量表明，根据盘中最大的H II区的光度，早期型螺旋可以分为两大类。第一类包括单个H II区LHα < 1039 ergs-1的星系。大多数第一类星系的形态似乎是不受干扰的，但在核Hα性质上显示出广泛的多样性。第二类包括至少有一个H II区的星系，LHα ≥ 1039 ergs-1。所有2类星系都显示出突出的尘埃带或其他形态学特征，如潮汐尾，这表明2类星系中异常明亮的H II区域可能是由于最近的相互作用而形成的。这些观测是正在进行的Hα巡天的一部分，揭示了早期螺旋星系是一个异质的星系，在当前的时代正在演变。我们还发现了第二总表和修正的夏普利-艾姆斯星表中旋涡星系分类之间的一些系统差异，这些差异可以追溯到用于分类旋涡星系的标准的应用中的细微变化。对早期研究的检验表明，关于螺旋星系中星星形成速率的哈勃型依赖性的看法取决于星表的选择。
Hα and continuum images are presented for 27 nearby early-type (Sa–Sab) spiral galaxies. Contrary to popular perception, the images reveal copious massive star formation in some of these galaxies. A determination of the Hα morphology and a measure of the Hα luminosity suggest that early-type spirals can be classified into two broad categories based on the luminosity of the largest H II region in the disk. The first category includes galaxies for which the individual H II regions have LHα < 1039 ergs s-1. Most of the category 1 galaxies appear to be morphologically undisturbed but show a wide diversity in nuclear Hα properties. The second category includes galaxies that have at least one H II region in the disk with LHα ≥ 1039 ergs s-1. All category 2 galaxies show either prominent dust lanes or other morphological peculiarities such as tidal tails, which suggests that the anomalously luminous H II regions in category 2 galaxies may have formed as a result of a recent interaction. The observations, which are part of an ongoing Hα survey, reveal early-type spirals to be a heterogeneous class of galaxies that are evolving in the current epoch. We have also identified some systematic differences between the classifications of spiral galaxies in the Second General Catalog and the Revised Shapley-Ames Catalog that may be traced to subtle variations in the application of the criteria used for classifying spiral galaxies. An examination of earlier studies suggests that perceptions concerning the Hubble-type dependence of star formation rates among spiral galaxies depends on the choice of catalog.