Rapidly oscillating Ap (roAp) stars have rarely been found in binary or higher order multiple systems. This might have implications for their origin.
We intend to study the multiplicity of this type of chemically peculiar stars, looking for visual companions in the range of angular separation between 0.05" and 8".
We carried out a survey of 28 roAp stars using diffraction-limited near-infrared imaging with NAOS-CONICA at the VLT. Additionally, we observed three non-oscillating magnetic Ap stars.
We detected a total of six companion candidates with low chance projection probabilities. Four of these are new detections, the other two are confirmations. An additional 39 companion candidates are very likely chance projections. We also found one binary system among the non-oscillating magnetic Ap stars. The detected companion candidates have apparent K magnitudes between 6.8 and 19.5 and angular separations ranging from 0.23" to 8.9", corresponding to linear projected separations of 30-2400AU.
While our study confirms that roAp stars are indeed not very often members of binary or multiple systems, we have found four new companion candidates that are likely physical companions. A confirmation of their status will help understanding the origin of the roAp stars.
Rapidly oscillating Ap stars observed with TESS. The LAMOST Ap sample and 49 Cam
Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto（波尔图大学空间与天体物理研究所）；Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto（波尔图大学理学院物理与天文学系）；South African Astronomical Observatory（南非天文台）；School of Physics, Engineering and Technology, University of York（约克大学物理、工程与技术学院）；DTU Space, Technical University of Denmark（丹麦技术大学空间中心）；Centre for Space Research, North-West University（西北大学太空研究中心）；Jeremiah Horrocks Institute, University of Lancashire（兰开夏大学杰里米亚·霍罗克斯研究所）；Department of Astronomy, Cornell University（康奈尔大学天文学系）；Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM（巴黎萨克雷大学、巴黎西岱大学、法国原子能与替代能源委员会、法国国家科学研究中心、天体物理学与信息分子研究所）
Rapidly varying A-type stars in the SuperWASP archive
对凌日系外行星的搜索已经产生了数百万颗恒星的大量时间分辨光度数据。其中一个主要的地面调查是SuperWASP项目。我们目前的调查超过150万的A型星在寻找高频脉动使用SuperWASP测光的初步结果。在宽波段测光中，我们能够探测到低至0.5毫磁级的脉动。这使得发现了几个快速振荡的Ap星和超过200个频率超过50 d $^{-1}$的盾牌座δ星，以及至少一个脉动sdB星。如此大量的结果使我们能够统计研究roAp和delta Scuti星之间的频率重叠，并利用现有数据探索更高的频率区域。
