螺旋星系和椭圆星系的合并（S+E合并）尽管对星系演化很重要，但迄今为止的研究很少。NGC 4441是这种合并的高级残留物的附近候选者，显示出典型的潮汐结构，如光学尾巴和两个外壳以及两个HI尾巴。分子气体含量的研究为最近的合并事件对恒星形成的影响提供了线索。模拟的S+E合并预测矛盾的情况下，强度和程度的诱导星爆。因此，需要观测恒星形成的原材料分子气体的数量和分布，以了解合并对恒星形成历史的影响。12 CO和13 CO（1-0）和（2-1）的观测是使用Onsala空间天文台20米和IRAM 30米望远镜以及Plateau de Bure干涉仪获得的。这些数据使我们能够对分子气体的性质进行基本分析，例如估计分子气体的质量，温度和密度以及恒星形成效率。CO的观测结果显示，分子气藏扩展到约4kpc，总分子气体质量约为5x10^8 M_sun。此外，高分辨率成像显示了一个中心分子气体特征，很可能是一个旋转的圆盘，容纳了大部分的分子气体~4x10^8 M_sun。这个核盘显示出与大规模HI结构不同的旋转方向，表明一个运动学解耦的核心。（略）
英文摘要：
Mergers between a spiral and an elliptical (S+E mergers) are poorly studied so far despite the importance for galaxy evolution. NGC4441 is a nearby candidate for an advanced remnant of such a merger, showing typical tidal structures like an optical tail and two shells as well as two HI tails. The study of the molecular gas content gives clues on the impact of the recent merger event on the star formation. Simulations of S+E mergers predict contradictory scenarios concerning the strength and the extent of an induced starburst. Thus, observations of the amount and the distribution of the molecular gas, the raw material of star formation, are needed to understand the influence of the merger on the star formation history. 12CO and 13CO (1-0) and (2-1) observations were obtained using the Onsala Space Observatory 20m and IRAM 30m telescope as well as the Plateau de Bure interferometer. These data allow us to carry out a basic analysis of the molecular gas properties such as estimates of the molecular gas mass, its temperature and density and the star formation efficiency. The CO observations reveal an extended molecular gas reservoir out to ~4kpc, with a total molecular gas mass of ~5x10^8 M_sun. Furthermore, high resolution imaging shows a central molecular gas feature, most likely a rotating disc hosting most of the molecular gas ~4x10^8 M_sun. This nuclear disc shows a different sense of rotation than the large-scale HI structure, indicating a kinematically decoupled core. (abbreviated)
Outflowing shocked gas dominates the NIR H$_2$ emission from the dual AGN NGC6240
Institute of Theoretical Astrophysics, University of Oslo（奥斯陆大学理论天体物理研究所）；European Southern Observatory (ESO)（欧洲南方天文台）；National and Kapodistrian University of Athens（雅典国立卡波蒂斯坦大学）；INAF - Osservatorio Astronomico di Brera（意大利国家天体物理研究所布雷拉天文台）；Università degli Studi di Bologna（博洛尼亚大学）；INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna（意大利国家天体物理研究所博洛尼亚空间科学天文台）；ASTRON, The Netherlands Institute for Radio Astronomy（荷兰射电天文研究所）；Kapteyn Astronomical Institute（卡普坦天文研究所）；University of South Carolina（南卡罗来纳大学）
