The evolution of the magnetic interaction between stars, discs, and planets

恒星、盘和行星之间磁相互作用的演化

• 批准号: ST/G006261/1
• 负责人: Scott Gregory
• 金额: $ 30.39万
• 依托单位: UNIVERSITY OF EXETER
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FG006261%2F1
• 关键词: evolution; magnetic; interaction; between; stars

Some of the most intense solar fireworks have directly affected modern life on Earth. Rapid increases in solar activity sends fluxes of charged particles towards our planet, giving rise to Aurora and disrupting satellite communications. Yet however spectacular the events on our Sun may seem today, our middle-aged star is comparatively quiet, and hides an even more violent past. A few billion years ago the Sun was a contracting ball of hot gas, although it was still too cool within its core to fuse hydrogen into helium and shine as it does today. Young solar analogues, called T Tauri stars, are about a million times too faint to be seen with the naked eye. Space satellite observations, however, have shown that they are typically 1000 times more active in X-rays than the Sun is presently. They are surrounded by large dusty planet-forming discs, which are bombarded by X-rays arising from violent stellar magnetic events. T Tauri stars are new-born stars which are still shrinking down under gravity to their adult proportions. As such stars collapse they should start to spin faster and faster, just like an ice-skater who pulls their arms in closer to their body. However, such stars are observed to be spinning slowly, an effect that has been attributed to how their strong magnetic fields interact with the gas and dust within their planet-forming discs. T Tauri stars are embedded in a web of magnetic field which binds them to the gas and dust within the disc. It is expected that this magnetic web acts as a brake, allowing the star to remain spinning slowly. This process, however, is poorly understood. Using a technique called Zeeman-Doppler imaging I have been able to determine the structure of their magnetic webs. This technique has strong parallels to the tomographic methods applied to construct 3D images of internal organs of the human body. This newly available data signals the beginning of a fresh era of research in to the formation of solar-like stars. My research will exploit this new stream of data, to investigate how forming stars interact with, and disrupt, their circumstellar environments. Ultimately this work will provide insight into the formation of our own Sun, and Solar System, at a time when the planets were just beginning to form. Roughly 300 planets have now been found orbiting other stars. It recently been discovered that some of these stars twinkle on the same timescale as it takes their planets to complete an orbit. This effect may be caused by highly energetic particles crashing into the stellar surface after being accelerated along strands of the magnetic web connecting the planet to the star. I will investigate this process in detail during the STFC fellowship.

一些最强烈的太阳烟花直接影响了地球上的现代生活。太阳活动的快速增加将带电粒子流发送到我们的星球，导致极光的出现并扰乱卫星通信。然而，无论今天太阳上发生的事件看起来多么壮观，我们的中年恒星相对安静，并且隐藏着更加暴力的过去。几十亿年前，太阳是一个收缩的热气体球，尽管它的核心仍然太冷，无法将氢融合成氦并像今天一样发光。年轻的太阳类似物，称为金牛座 T 星，其亮度大约是肉眼可见的一百万倍。然而，太空卫星观测表明，它们的 X 射线活跃程度通常是太阳目前的 1000 倍。它们被巨大的尘埃行星形成盘包围，这些行星盘受到剧烈恒星磁事件产生的 X 射线的轰击。金牛座T型恒星是新生恒星，它们仍在重力作用下收缩至成年比例。当这些恒星坍塌时，它们应该开始旋转得越来越快，就像滑冰者将手臂拉近身体一样。然而，人们观察到这些恒星旋转缓慢，这种效应归因于它们的强磁场与行星形成盘内的气体和尘埃相互作用。金牛座T型恒星嵌入磁场网络中，将它们与盘内的气体和尘埃结合在一起。预计这个磁网会起到刹车的作用，让恒星保持缓慢旋转。然而，人们对这一过程知之甚少。使用一种称为塞曼多普勒成像的技术，我已经能够确定它们的磁网的结构。该技术与用于构建人体内部器官 3D 图像的断层扫描方法有很强的相似之处。这些新数据标志着类太阳恒星形成研究新时代的开始。我的研究将利用这一新的数据流，研究形成中的恒星如何与其星周环境相互作用并扰乱其周围环境。最终，这项工作将深入了解我们自己的太阳和太阳系的形成，当时行星刚刚开始形成。目前已发现大约 300 颗行星绕其他恒星运行。最近发现，其中一些恒星的闪烁时间与它们的行星完成轨道运行的时间尺度相同。这种效应可能是由于高能粒子沿着连接行星和恒星的磁网加速后撞击恒星表面而引起的。我将在 STFC 奖学金期间详细研究这个过程。

项目成果

The soft X-ray light curves of partially eclipsed stellar flares Eclipsing of stellar flares

部分食恒星耀斑的软 X 射线光变曲线 食恒星耀斑

• DOI: 10.1111/j.1365-2966.2011.19666.x
• 发表时间: 2012
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: Johnstone C

Complex magnetic topology and strong differential rotation on the low-mass T Tauri star V2247 Oph

• DOI: 10.1111/j.1365-2966.2009.15998.x
• 发表时间: 2009-11
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: J. Donati;M. Skelly;J. Bouvier;M. Jardine;S. Gregory;J. Morin;G. Hussain;C. Dougados;F. Ménard;Y. Unruh

Coordinated Optical/X-ray observations of the CTTS V2129 Oph The Chandra View

CTTS V2129 Oph 的协调光学/X 射线观测 Chandra View

• 发表时间: 2011
• 期刊: Astronomical Society of the Pacific Conference Series
• 作者: Flaccomio, Ettore

Variable X-ray emission from the accretion shock in the classical T Tauri star V2129 Ophiuchi

• DOI: 10.1051/0004-6361/201016321
• 发表时间: 2011-06-01
• 期刊: ASTRONOMY & ASTROPHYSICS
• 影响因子: 6.5
• 作者: Argiroffi, C.;Flaccomio, E.;Walter, F. M.
• 通讯作者: Walter, F. M.

Testing the Ability of Field Extrapolation Models to Predict the X-ray Emission Properties of Pre-Main Sequence Stars

测试场外推模型预测前主序星 X 射线发射特性的能力

• 发表时间: 2010
• 期刊: AAS/High Energy Astrophysics Division #11
• 作者: Gregory Scott G.