论文标题
附近星系（Heron）II的光环和环境II：边缘星系的外部结构
The Halos and Environments of Nearby Galaxies (HERON) II: The outer structure of edge-on galaxies
论文作者
论文摘要
苍鹭项目旨在研究星系附近的光环和低表面亮度细节。在第二张苍鹭纸中，我们将详细考虑35个星系中的深层成像（降至28 mag/arcsec $^2 $）的表面亮度），可查看边缘。我们证实了文献中先前描述的一系列低表面亮度特征，但也报告了新的表面亮度。我们将观察到的星系的外形分类为三种主要类型（及其原型）：盘/钻石样（NGC891），椭圆形（NGC4302）和Boxy（NGC3628）。我们表明，星系中的外盘的形状通常不经常遵循指数盘的一般3D模型：我们的样品中的17个星系在外围展示了椭圆形甚至是方形的同流。另外，我们表明，外盘的变形越小，其结构越椭圆形或散叉。我们样品中的许多星系具有不对称的外部结构。我们建议观察到的星系外部形状的多样性是由合并历史及其强度定义的：如果没有最近发生多个次要或单个主要合并，则外部形状是钻石状的或刻薄的。相反，相互作用的星系显示出椭圆形的外形，而最近的合并似乎将外部形状转化为方形。
The HERON project is aimed at studying halos and low surface brightness details near galaxies. In this second HERON paper we consider in detail deep imaging (down to surface brightness of ~28 mag/arcsec$^2$ in the r band) for 35 galaxies, viewed edge-on. We confirm a range of low surface brightness features previously described in the literature but also report new ones. We classify the observed outer shapes of the galaxies into three main types (and their prototypes): disc/diamond-like (NGC891), oval (NGC4302), and boxy (NGC3628). We show that the shape of the outer disc in galaxies does not often follow the general 3D model of an exponential disc: 17 galaxies in our sample exhibit oval or even boxy isophotes at the periphery. Also, we show that the less flattened the outer disc is, the more oval or boxy its structure. Many galaxies in our sample have an asymmetric outer structure. We propose that the observed diversity of the galaxy outer shapes is defined by the merger history and its intensity: if no recent multiple minor or single major merging took place, the outer shape is diamond-like or discy. On the contrary, interacting galaxies show oval outer shapes, whereas recent merging appears to transform the outer shape to boxy.
