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首页> 外文期刊>The Astrophysical journal >CENTRAL STAR FORMATION AND PAH PROFILES IN PSEUDOBULGES AND CLASSICAL BULGES
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CENTRAL STAR FORMATION AND PAH PROFILES IN PSEUDOBULGES AND CLASSICAL BULGES

机译：假凸珠和经典凸起中的中央恒星形成和PAH特征

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摘要

I use Spitzer 3.6-8.0 μm color profiles and surface brightness profiles of polycyclic aromatic hydrocarbons (PAHs) to compare the radial structure of star formation in pseudobulges and classical bulges. Pseudobulges are "bulges" that form through secular evolution, rather than mergers. In this study, pseudobulges are identified using the presence of disklike structure in the center of the galaxy (nuclear spirals, nuclear bars, and high ellipticity in bulge); classical bulges are those galaxy bulges with smooth isophotes that are round compared to the outer disk and show no disky structure in their bulge. I show that galaxies structurally identified as having pseudobulges have higher central star formation rates than those of classical bulges. Furthermore, I also show that galaxies identified as having classical bulges have remarkably regular star formation profiles. The color profiles of galaxies with classical bulges show a star-forming outer disk with a sharp change, consistent with a decline in star formation rates, toward the center of the galaxy. Classical bulges have a nearly constant inner profile (r is contained in 1.5 kpc) that is similar to elliptical galaxies. Pseudobulges in general show no such transition in star formation properties from the outer disk to the central pseudobulge. Thus, I conclude that pseudobulges and classical bulges do in fact form their stars via different mechanisms. Furthermore, this adds to the evidence that classical bulges form most of their stars in fast episodic bursts, in a similar fashion to elliptical galaxies, whereas pseudobulges form stars from longer lasting secular processes.
机译：我使用Spitzer 3.6-8.0μm多环芳烃（PAH）的颜色轮廓和表面亮度轮廓来比较假凸起和经典凸起中恒星形成的径向结构。伪凸起是通过世俗进化而非合并形成的“凸起”。在这项研究中，假凸起是通过在银河系中心存在盘状结构（核螺旋，核棒和凸起中的高椭圆率）来识别的。经典的凸起是那些具有光滑等视线的星系凸起，与外盘相比，它们是圆形的，并且在凸起中没有任何盘状结构。我发现在结构上被确定为具有假凸起的星系比经典凸起的星体具有更高的中心星形成率。此外，我还表明，被鉴定为具有经典凸起的星系具有非常规则的恒星形成轮廓。具有经典凸起的星系的颜色轮廓显示出一个形成恒星的外盘，其朝着星系的中心急剧变化，这与恒星形成率的下降相一致。经典凸起的内部轮廓几乎恒定（r包含在1.5 kpc中），类似于椭圆星系。伪隆起一般没有显示出恒星形成特性从外盘到中央伪隆起的这种过渡。因此，我得出结论，伪凸起和经典凸起确实通过不同的机制形成了恒星。此外，这增加了证据，即经典凸起以快速的情节爆发形式形成了大多数恒星，其形成方式类似于椭圆星系，而伪凸起则是由持续时间较长的世俗过程形成的。

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  • 来源
    《The Astrophysical journal》 |2006年第1pt2期|p.L17-L20|共4页
  • 作者

    DAVID B. FISHER;

  • 作者单位

    Department of Astronomy, University of Texas, 1 University Station, Austin, TX 78712;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 天文学;
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