EAPSI: Using Seismic Waves to Probe the Structure of Colliding Stars

EAPSI：利用地震波探测碰撞恒星的结构

• 批准号: 1713918
• 负责人: Emily Leiner
• 金额: $ 0.54万
• 依托单位: Leiner Emily
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-06-01 至 2018-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1713918&HistoricalAwards=false
• 关键词: EAPSI; Using; Seismic; Waves; Probe

Blue stragglers are stars that have recently gained mass by colliding with a passing star, or accreting material from a binary companion. Similar interactions are responsible for creating many other interesting objects, including the Type 1a supernovae we use to measure the expansion of the universe. To better understand these processes, astronomers need reliable measurements of the mass and internal structure of mass-transfer and collision products like blue stragglers. Such measurements only recently became possible using a new technique called asteroseismology. Similar to seismologists using earthquakes to study the interior of the Earth, astronomers use seismic waves that propagate inside stars to probe their interior structures. These wave patterns can be detected as small variations in a star's brightness. NASA's Kepler mission has monitored the brightness of thousands of stars for four years, providing a groundbreaking data set to study these seismic waves. This project will study a sample of blue stragglers observed by Kepler, using their seismic wave patterns to determine their masses, rotation rates, and internal structures. This research will be done in collaboration with Dr. Dennis Stello at the University of New South Wales, one of a handful of experts on asteroseismology in the world. Two key uncertainties in the physics of collisions and binary mass transfer are the mass transfer efficiency and the angular momentum evolution. In combination with detailed stellar modeling, asteroseismology can shed light on mass transfer efficiency by providing precise mass measurements of blue stragglers, a constraint that has been largely unavailable to modelers. Some blue stragglers display mixed p- and g- mode oscillations, allowing separate measurements of core and envelope properties. For this project, measuring a core and an envelope rotation rate will illuminate how much angular momentum is accreted at the blue straggler surface, and if it is transported down into the stellar core. This technique has already offered many insights into angular momentum transport in normal stars. This project will be one of the first efforts to measure these properties in non-standard stars like blue stragglers, and promises to offer more insight into the angular momentum evolution of mass-transfer and collision products. This award, under the East Asia and Pacific Summer Institutes program, supports summer research by a U.S. graduate student and is jointly funded by NSF and the Australian Academy of Science.

蓝色散星是最近通过与路过的恒星碰撞或吸收双星伴星的物质而获得质量的恒星。类似的相互作用也创造了许多其他有趣的天体，包括我们用来测量宇宙膨胀的1a型超新星。为了更好地理解这些过程，天文学家需要可靠地测量质量和内部结构的质量和内部结构的物质转移和碰撞产物，如蓝色散布。直到最近，使用一种名为星震学的新技术才有可能进行这种测量。类似于地震学家使用地震来研究地球内部，天文学家使用在恒星内部传播的地震波来探测它们的内部结构。这些波型可以检测到恒星亮度的微小变化。NASA的开普勒任务四年来一直在监测数千颗恒星的亮度，为研究这些地震波提供了突破性的数据集。这个项目将研究开普勒观测到的蓝离散星样本，利用它们的地震波模式来确定它们的质量、自转速度和内部结构。这项研究将与新南威尔士大学的丹尼斯·斯特洛博士合作完成，斯特洛博士是世界上为数不多的星震学专家之一。碰撞和二元传质物理中的两个关键不确定因素是传质效率和角动量演化。与详细的恒星模型相结合，星震学可以通过提供蓝色散布星的精确质量测量来揭示质量传递效率，这是建模人员基本上无法获得的限制。一些蓝色散射体表现出混合的p-模和g-模振荡，允许分开测量核心和包络特性。对于这个项目，测量核心和包络自转速度将阐明在蓝色散布星表面吸积了多少角动量，以及它是否被输送到恒星核心。这项技术已经提供了许多关于正常恒星角动量运输的见解。这个项目将是第一批在像蓝色散布星这样的非标准恒星中测量这些性质的努力之一，并有望为质量转移和碰撞产物的角动量演化提供更多的洞察力。该奖项根据东亚和太平洋夏季学院计划，支持一名美国研究生的暑期研究，由NSF和澳大利亚科学院联合资助。