标题： 年轻的B型五重系统HD 155448 显示英文标题

标题： The young B-star quintuple system HD 155448

摘要： 到目前为止，HD 155448 被认为是一颗后AGB星，并被列为四重系统。 在本文中，我们深入研究了该系统，并揭示出B成分本身是一个双星，而HD 155448 A、B1、B2、C和D这五颗恒星可能形成一个共动恒星系统。 通过光谱分析，我们得出了光谱类型，并发现所有组分都是B型矮星（A：B1V，B1：B6V，B2：B9V，C：B4Ve，D：B8V）。 它们的恒星年龄接近ZAMS，它们的距离估计约为2 kpc。 特别值得注意的是C成分，在光学波长下显示出强烈的氢和禁线发射线。 所有发射线在东方方向上是空间扩展的，并且除了[OI]线外，似乎具有相似的速度偏移。 在红外图像中，我们在HD 155448 C的东北方向看到一个弧形结构。 从光学到10微米，大部分的星际辐射位于距离HD 155448 C约1.0角秒到3.0角秒之间，而在Q波段，弧形结构似乎与HD 155448 C接触。 Spitzer和VLT/VISIR中红外光谱显示，靠近恒星的星际物质由硅酸盐组成，而在距离大于1角秒的地方，多环芳烃（PAH）主导了辐射，在8.6、11.3和12.7微米处有带。 我们考虑了几种情景来解释星际物质不寻常的、不对称的、弧形的几何结构。 最可能的解释是喷流与恒星形成过程的残留物质碰撞。 显示英文摘要

摘要： Until now, HD 155448 has been known as a post-AGB star and listed as a quadruple system. In this paper, we study the system in depth and reveal that the B component itself is a binary and that the five stars HD 155448 A, B1, B2, C, and D likely form a comoving stellar system. From a spectroscopic analysis we derive the spectral types and find that all components are B dwarfs (A: B1V, B1: B6V, B2: B9V, C: B4Ve, D: B8V). Their stellar ages put them close to the ZAMS, and their distance is estimated to be ~2 kpc. Of particular interest is the C component, which shows strong hydrogen and forbidden emission lines at optical wavelengths. All emission lines are spatially extended in the eastern direction and appear to have a similar velocity shift, except for the [OI] line. In the IR images, we see an arc-like shape to the northeast of HD 155448 C. From the optical up to 10 micron, most circumstellar emission is located at distances between ~1.0 arcsec and 3.0 arcsec from HD 155448 C, while in the Q band the arc-like structure appears to be in contact with HD 155448 C. The Spitzer and VLT/VISIR mid-IR spectra show that the circumstellar material closest to the star consists of silicates, while polycyclic aromatic hydrocarbons (PAH) dominate the emission at distances >1 arcsec with bands at 8.6, 11.3, and 12.7 micron. We consider several scenarios to explain the unusual, asymmetric, arc-shaped geometry of the circumstellar matter. The most likely explanation is an outflow colliding with remnant matter from the star formation process.