High Sensitivity Array Studies of Stellar Radio Coronae

恒星射电日冕的高灵敏度阵列研究

• 批准号: 0908941
• 负责人: Robert Mutel
• 金额: $ 40.91万
• 依托单位: University of Iowa
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-06-01 至 2013-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0908941&HistoricalAwards=false
• 关键词: Sensitivity; Array; Studies; Stellar; Radio

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Dr. Robert L. Mutel of the University of Iowa and his students will undertake a research program to image the radio coronae of several active late-type binary stars at multiple epochs with unprecedented sensitivity, angular resolution, and positional accuracy. The systems will be imaged using the High Sensitivity Array (HSA), the world's most powerful radio imaging long-baseline array. The program will combine the imaging power of the HSA with observational strategies that optimize positional accuracy, allowing registration of the component star positions on the radio maps with an absolute accuracy approximately one stellar radius. These images will reveal, for the first time, the relationship between extended radio coronae and the parent star system: Whether the radio emission originates on a single star or is generated in the inter-binary region, whether large-scale coronal loops exist, and if radio flares arise near the stellar surface or perhaps at the top of loops. In addition to stellar astrophysical results, fundamental parameters such as distance, proper motion, and binary orbital orientation will be determined with an accuracy significantly better than current ground- or space-based optical surveys. The multi-epoch HSA radio maps will allow the first detailed, systematic determination of the morphology of the radio coronae of late-type active stars. This is vital in testing existing models of stellar coronae, which are largely based on spectral measurements of the integrated radio and/or x-ray corona, with little or no spatial information. One key test will be to resolve competing hypotheses of radio coronal geometry, such as polar models, dipole traps, and accretion disk-driven inter-binary emission regions. Another will be to establish whether large-scale magnetic loops or other structures are a common feature in active stellar coronae, and if so, to establish their sizes and temporal evolution.High-fidelity radio maps, combined with accurate overlaid stellar positions, will significantly guide development of comprehensive models of stellar coronae which incorporate x-ray, optical, and UV observations in a unified theoretical framework. Also, since the target stars are all optically bright, the ability to measure stellar radio positions with high accuracy will be very useful in tying the optical and radio coordinate frames together with sub-milliarcsecond precision. This is a long-standing goal vital to many astrophysical disciplines, including future astrometric space missions such as Gaia and PlanetQuest.

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助。爱荷华州大学的Mutel和他的学生将进行一项研究计划，以前所未有的灵敏度，角分辨率和位置精度在多个时期对几个活跃的晚型双星的无线电日冕进行成像。这些系统将使用高灵敏度阵列（HSA）进行成像，这是世界上最强大的无线电成像长基线阵列。该计划将联合收割机的成像能力与观测策略相结合，优化位置精度，允许在无线电地图上以大约一个恒星半径的绝对精度登记组成星星的位置。这些图像将首次揭示扩展的无线电日冕与母星星系统之间的关系：无线电发射是起源于单个星星还是在双星间区域产生，是否存在大规模的日冕环，以及无线电耀斑是否出现在恒星表面附近或可能在环的顶部。 除了恒星天体物理学结果外，还将确定距离、自行和双星轨道方向等基本参数，其准确度将大大高于目前的地面或空间光学测量。多历元HSA无线电地图将允许第一次详细，系统地确定晚型活跃恒星的无线电日冕的形态。这对于测试现有的恒星日冕模型至关重要，这些模型主要基于综合无线电和/或X射线日冕的光谱测量，很少或没有空间信息。一个关键的测试将是解决射电日冕几何形状的竞争假设，如极模型，偶极子陷阱，吸积盘驱动的双星间发射区。另一个将是确定是否大规模的磁环或其他结构是一个共同的特点，在活跃的恒星冕，如果是这样，建立他们的大小和时间的演变高保真无线电地图，结合准确的恒星位置重叠，将显着指导发展的综合模型的恒星冕，其中包括X射线，光学和紫外线观测在一个统一的理论框架。此外，由于目标恒星都是光学明亮的，因此以高精度测量恒星射电位置的能力将非常有用，可以将光学和射电坐标系与亚毫弧秒精度联系在一起。这是一个长期的目标，对许多天体物理学科至关重要，包括未来的天体测量太空任务，如盖亚和行星探索。